A330 cargo aircraft available in two different shapes either:

1. A330-200F was originally manufactured by airbus as cargo aircraft starting from January 2010.
   or
2. available as A330 passenger to freight P2F converted aircraft through EFW company based in Dresden Germany starting from December 2017.

A330 cargo aircraft areas:

Figure 1: A330 Cargo aircraft areas

in A330 cargo aircraft upper fuselage includes:

• cockpit,
• courier area,
• and the main deck cargo compartment,

lower fuselage includes:

• avionics compartment,
• the lower deck forward
• and aft cargo compartments

lower fuselage in A330 cargo aircraft is the same as in A330 passenger aircraft the cockpit or the flight deck is the area where the pilot set to fly an airplane it includes seats for the captain, first officer, third occupant, and fourth occupant

Figure 2: A330 Cockpit (Flight Deck)

The courier area is in the forward entrance area and contains a lavatory, galley, and seats for the company staff.

Figure 3: courier area

The courier area may include an optional flight-crew rest compartment (FCRC) for pilots rest in long flights,

Figure 4: A330 P2F Courier area FCRC

the main deck cargo compartment used for loading containers and pallets also may include the option cargo loading system for rapid loading and unloading

Figure 5: A330 Cargo - Main Deck Cargo Compartment (MDCC)

Cargo or freighter aircraft main deck cargo compartments are classified as class E compartments.

Class E cargo compartment requirement according to civil aviation regulation:

1. the compartment needs to be equipped with a smoke detection system.
2. Ventilation control system. 
3. Flight crew procedure for fire suppression. No active fire fighting system.
4. The smoke barrier between the main deck cargo compartment and courier area.

Figure 6: MDCC classified as Class E compartments

A330 “Class E” MDCC Fire Protection Systems:

 For A330 Class E main deck cargo compartment fire protection system we will cover the following points

1. 1. Main deck cargo compartment smoke detection system.
   2. Main deck cargo compartment smoke barrier.
   3. Main deck cargo compartment fire suppression system
   4. main deck cargo compartment smoke and crew oxygen requirements

1. Main deck cargo compartment smoke detection system.

Figure 7: MDCC SMOKE DETECTION

The smoke detectors of the main deck cargo compartment. are installed in pairs in the main deck cargo compartment ceiling. A330-200F is equipped with a dual-loop smoke detection system which includes fifteen pairs of smoke detectors the smoke detectors are connected to the smoke detection function of the CIDS director, when the CIDS smoke detection function confirmed smoke detection in the main deck cargo compartment it launches warning in the cockpit,  courier area, and the main deck cargo compartment.

Figure 8: A330-200F MDCC SMOKE DETECTION

In Figure 9  the A330-200F main deck cargo compartment smoke indication and the control panel located in the cockpit overhead panel right-hand side.

Figure 9: A330-200F MDCC Smoke Indication and Control Panel

A330-200 P2F is equipped with a dual-loop smoke detection system which includes fifteen (15) pairs of smoke detectors the smoke detectors are connected to the main deck cargo smoke control panel (MDC-SCP) in the cockpit overhead panel the system is a stand-alone system with no interface to the existing smoke detection control unit (SDCU) or CIDS computers.

Figure 10: A33-200 P2F MDCC Smoke Detection System

A330-300 P2F same as A330-200 P2F but the main deck cargo compartment is equipped with seventeen smoke detectors instead of seventy pairs of smoke detectors instead of fifteen pairs because the A330-300 fuselage is longer than the A330-200 fuselage, figure 10 shows the main deck cargo smoke control panel (MDC-SCP) for both A330-200 P2F and A330-300 P2F located in the cockpit overhead panel right-hand side  Main deck cargo compartment smoke indication.

Figure 10: A33-300 P2F MDCC Smoke Detection System

Figure 11: A330 P2F Main Deck Cargo Smoke Control Panel (MDC-SCP)

1. Cockpit indications

   – The related SMOKE warning light illuminate

   – The MASTER WARNING red light flash

   – The Continuous Repetitive Chime to sound

   – A Red warning message on the upper ECAM display

2. Courier area indication

   – The "No Smoking" and "Fasten Seat Belt" signs illuminate

3. MDCC indications

   – The ″LEAVE COMPARTMENT″ signs illuminate

   – The smoke chime rings (sequence of continuous single-tone, high pitched chime)

Figure 12: MDCC signs and loud speakers

The A330-200 P2F MDCC is equipped with 10 lighted signs "LEAVE COMPARTMENT“ and 14 loudspeakers. For aural warning in case of smoke in the main deck cargo compartment, The ″LEAVE COMPARTMENT″ signs illuminate and, the smoke chime rings.

2. MDCC compartment, smoke barrier:

The smoke barrier protects occupied areas like the cockpit and courier area against the hazardous quantity of fumes and smoke from the main deck cargo compartment

A330-200F equipped with a rigid wall barrier with two access doors the rigid wall barrier work as a smoke barrier in case of main deck cargo compartment fire

Figure 13: A330-200F Rigid Wall Barrier

A330 P2F is equipped with a 9G barrier net from the courier area side and a smoke curtain from the MDCC side the smoke curtain has two access doors the smoke curtain work as a smoke barrier in case of main deck cargo compartment fire.

Figure 14: A330 P2F 9G barrier net from courier area side

Figure 15: A330 P2F Smoke Curtain from MDCC side

3. Main deck Cargo compartment Fire suppression system:

When the MDCC smoke is detected, the system automatically isolates the airflow to the Compartment through :

• Closing the Main Deck Shut-off valves (MSOV)
• Opening the Main Deck Bypass Valve (MBV)
• Closing the Galley &Toilet extraction fan
• Closing the CAB Recirculation FAN
• Shutting off PACK 1 (and PACK 2 automatically goes high flow)
• Closing the LD FWD, LD AFT, and BULK cargo compartments isolation valves.

Figure 16: MDCC Fire Suppression System

 

in addition to main deck cargo compartment airflow isolation which carried out automatically after a smoke detection
no active fire extinguishing system is installed in the main deck cargo compartment, the fire fighting procedure is based on the depressurization of the main deck by increasing manually the cabin altitude up to twenty thousand feet while simultaneously reducing cruising flight attitude to twenty thousand feet the procedure reduces the oxygen concentration in the air And consequently suppresses the fire.

4. Main deck cargo compartment, smoke, and the crew oxygen requirement.

The freighter oxygen system gives hypoxia protection to the cockpit crew and the courier area occupants after a cabin decompression for (15 min), during the cargo smoke evacuation procedure for (up to 180 minutes ETOPS diversion time)

Figure 17: Crew Oxygen Masks

the flight compartment is equipped with four oxygen masks as shown because the flight crew members vary from 2 to 4  pilots according to flight duration courier area occupants the number varies from 4 up to 6 occupants in the case of main deck cargo compartment smoke detection courier area oxygen system activated and the masks dropped automatically to supply the occupants with oxygen up to reaching aircraft attitude 10,000 feet before landing

Figure 18: Automatic activation of courier area oxygen system

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Nowadays it is obvious that the aircraft manufacturing industry market is quite delicate as well as competitive and companies operating in this sector are always looking for different ways in order to improve productivity and optimize the work process. Initially, the construction of aircraft involves very complex processes that require a specialized workforce and a lot of correctness during work performance. One of the many challenges to be considered in this sector is the human error that can cause losses of millions of dollars. In addition, the work of aircraft manufacturers does not end once an aircraft is produced. Maintenance of these manufactured aircraft is another complicated process that has its challenges and must be constantly followed for various malfunction problems that may be encountered. To successfully overcome the many difficulties and challenges that this industry has to face day by day, aircraft manufacturers must adopt the latest technologies in the market and at the same time meet the requirements to ensure a competitive position.

 Augmented Reality is the kind of technology that is providing solutions for many different companies. Many businesses have adopted this technology effectively in processes such as planning and production of their aircraft, thus proving that they can secure a role in the global market. Augmented Reality is an innovative technology that provides the overlays of digital content and information onto the physical world. Moreover, the usage of Augmented Reality Glasses can be considered as "the feature" that makes it possible to improve performance and minimize losses during various operational processes.

 As we mentioned above, Augmented Reality is experiencing countless benefits for many businesses operating in different fields, and in this article, we will take a general look at some of the applications in the aircraft manufacturing industry.

As we all know, aviation maintenance workers need to be fast and accurate enough in the performance of their tasks. Many of the risks that threaten this industry comes from the errors of these employees and in addition to financial damage in many cases have caused tragic accidents and loss of life. Augmented Reality technology plays a key role in providing real-time information and improves collaboration between the workforce by making them more engaged in their tasks. So, remote collaboration enabled by this technology makes it possible for the workforce to achieve profitable results in efficient ways and to overcome many unexpected challenges.

Augmented Reality now enables the support of on-site technicians through detailed information and guidance from highly specialized experts. This makes it possible for even hidden risks to be detected by experts through the "see-what-I-see" principle made possible by live video streaming and providing the full view of the technician's environment. Moreover, technicians are more flexible in performing tasks due to the use of smart glasses that create the ability to perform various processes hands-free without distractions. All this helps to reduce errors due to procedure violations, misinterpretation of data and information, or insufficient training.

In addition to improving distance collaboration, this technology also finds application in training inexperienced technicians and enabling an employee onboarding process as effectively as possible. Already Augmented Reality has proven to increase the efficiency and safety of training in this industry while reducing the very high costs for training that the workforce must pursue. Trainees are able to be adopted in a more engaging and interactive environment by using Augmented Reality.

Usually, in the malfunction occurrence of any of the aircraft, companies may lose significant amounts of money. As mentioned before Augmented Reality solution for real-time collaboration between technicians and experts eliminates any possible delays. Exchanging images and documents in real-time speeds up the repair process and all this translates into a greater Return on Investment.

What is summarized above in this article are just some of the cases of Augmented Reality applications in the aircraft manufacturing industry that start with the production process, maintenance, and repair. All this is done by enhanced communication and collaboration through the features that this technology offers in integration with smart glasses. The future looks even more promising, predicting new usage cases of this technology but also wider adoption by many companies that have already begun to explore the offered opportunities.

Airplanes Are Cleaner Than Ever

You have probably seen videos showing how most airlines are making a huge effort in cleaning their planes, planes are probably the cleanest they have been since they were new. Airlines are removing contact points at each phase of the journey.

Airlines are removing contact points at each phase of the journey. Image United

Airlines such as Emirates are adding additional flight attendants, to clean the bathroom every 90 minutes.

Emirates Flight Attendant wearing PPE, mask, gloves, and face cover. Image Emirates

Social Distancing Doesn't Work in The Air?

Most airlines will argue that social distancing doesn't work in the air, or at least as it would on the ground. Most airlines are selling the entirety of the seats; shutting out center seats is exceptionally impeding to the main concern of a carrier, particularly in a difficult financial time like at this point.

Instead, you have to wear a mask to fly. Most airlines are enforcing this rule. No Mask, No Fly. Airlines or airports are now handing out hygiene kits containing gloves, a face mask, antibacterial wipes, and hand sanitizer.

Emirates Hygiene Kit

Bring your own food onboard

We have seen some noteworthy downgrades on the in-flight services, particularly in meals and beverages.

The new keyword for meals is "sealed and wrapped". The food now comes in pre-packaged snack bags or in a snack box.

On-board US Domestic flights, the First Class traveler will now get a snack box rather than a plate with a hot dish. Economy passengers are getting a bag with a bottle of water and a snack

United Airlines Domestic Economy Class Snack Bag Content

Forget about the champagne flutes, wine glasses or even coffee mugs. Beverages will be individual bottled water only – no alcohol offerings – across all cabins, with only plastic cups available and also no ice on offer.

For long haul flying, British Airways unveiled a host of changes to their onboard dining experience. In all classes, meals will no longer be served in individual courses; each passenger will instead receive a snack box consistent with their class of travel.

Only First Class will receive a hot meal; while Business, Premium Economy, and Economy will only receive a cold meal. Moreover, the meal box is the same in Premium Economy and Economy.

BA First Class Meal Box

BA Club World Meal Box

BA Economy Meal Box

Passengers are welcome to bring their own food and refreshments on-board to enjoy during their journey.

Flying is For Essential Journeys, Less Fun and More Sombre Now

On my recent flight, everyone was wearing a mask and sitting quietly away from others. It was a quiet, somber experience without the usual chatter and laughter. Everyone was trying to avoid contact with other passengers.

International Flying will require a lot of cumbersome research, frustrating paperwork, travel approvals, and even COVID tests. You may have to go into quarantine for 14 days on arrival, regardless of your test results, which all makes flying a far more serious consideration. You can’t just jump on a plane last minute like you could before. Flying is for essential travel, not for entertainment only any longer.

During the era which the aircraft and aviation industry largely growth up, the aircraft manufacturer, and selected industry participants form groups called Maintenance Steering Groups (MSG).

This Maintenance Steering Group MSG aim to determine an appropriate time and to overhaul in fact all component (whether they need it or not was not a consideration). During the latter part of the 1960’s a task force was created to investigate more cost effective (but equally safe processes) from this, led the concept we now call “on condition maintenance”.

A document was produced during 1968 by ATA (Air Transport Association) -titled Maintenance Evaluation and Program Development, which also became known as “MSG-1” The process was trialed on the Boeing 747. The MSG-1 process used decision logic to develop scheduled maintenance.

MSG-2 was developed and used for developing scheduled maintenance for 1970’s, MSG-2 was process orientated and for first time introduced ‘condition monitored maintenance’ concept.

MSG-3 was first published in 1980 is a task orientated and the main idea behind this concept is to recognize the inherent reliability of aircraft systems and components, avoid unnecessary maintenance tasks and achieve increased efficiency.

Control Processes

1. Hard Time: life limit or maximum interval gave to the component until performing maintenance tasks on a part or unit. Such intervals apply to overhaul, but also to the total life of the part or unit.
2. On condition: mean we not left the component until it’s failure, but during its life we do repetitive inspections, test and analysis to measure part integrity and determine the conditions, then we can take the proper decision.So, we can define as maintenance process having repetitive inspections or tests to determine the condition of units, systems, or portions of structure with regard to continued service-ability (corrective action is taken when required by item condition.)
3. Condition Monitoring: means we left the component / part until it’s failure, but we pay attention to the part without any regular inspections, tests…etc.Simply we can define as a maintenance process which allows a unit to operate until failure. Condition monitoring is not permitted for units whose failure has an adverse effect on operational safety.
4. Zonal Inspection Programs: means to do regular inspection to the aircraft component according to different inspection programs like: Corrosion Protection Program CPP, sampling program…etc. these programs replace the condition monitoring in MSG3.The zonal inspection programs are very important and need to be done carefully to be effective because if not it may affect the safety.

Below table give brief difference between 3 revisions of MSG

What’s next?

After Maintenance Steering Groups (MSG) and Industry Steering Committees (ISC). through numerous meetings determine the frequency and scope of aircraft inspections to be performed. This information is provided to another group called the maintenance review board (MRB) group led by the Airworthiness Authority. The MRB will issue their final recommendations as a MRB Report (MRBR) to the manufacturer on how an aircraft should be maintained. The manufacturer then publishes this information in Maintenance Planning Documents (MPD) to be provided to the customer. For airline or commercial operators, the recommendations of the MRB and subsequent MPD are used to develop its Customized Maintenance Program (CMP).

Finally , if you want add extra information ,question or query we like to hear in the below comment

in this article, we clarify the difference between external and internal hydraulic leaks

External leak

External hydraulic fluid leakage is the most recognizable type of leakage. Even the untrained eye can easily spot a broken hose spewing oil like a Texas geyser. These types of leaks will typically be repaired quickly, because the equipment, production line or process will quickly come to a halt if the problem is ignored.

External leaks will results:

1. in a loss of system pressure,
2. loss of fluid,
3. a rise in the temperature of the remaining fluid
4. and cause a possible fire risk.

Internal leaks:

Internal planned leakage is typically small orifices or pathways that allow the hydraulic fluid from a higher pressurized zone of a system to travel into a lower pressurized zone to lubricate, clean and cool a specific component or area. These planned internal leaks do not allow the fluid to exit the hydraulic circuit, so there is no visual indication of its presence. The most common cause of excessive internal leakage is wear of component surfaces during normal operation.

The vast majority of hydraulic systems in operation today have leaks - leaks that are planned. They are designed with a specific function in mind, and in many cases, are documented by the original equipment manufacturer (OEM) as the amount of acceptable leakage under normal operating conditions.

Leakage can also result from poor system design, incorrect component selection, and poor quality control tolerances during the manufacturing of a component, and incorrect overhaul of rebuilt components.

System performance, reliability, and increased operating temperatures are the first visual signs of excessive internal leakage.

1. happens from high pressure to low,
2. causes a drop in system pressure,
3. more activity of pressure regulating or cut-out valves
4. and a rise in system temperature.
5. Internal leaks cause a rise in fluid
   temperature

Detection and quantification of the fluid consumption is the first step in external leak control. Up-to-date reservoir management records must be maintained to determine when by whom and how much fluid was required to top-up a reservoir. These records should be used along with visual inspections to determine the location and the leak rate of any detected anomalies.

References:

• 1.Photo by Fatima Garcia on Unsplash
• A320 Maintenance Manual

An emergency landing is a prioritized landing made by an aircraft in response to an emergency containing an imminent or ongoing threat to the safety of:

1- Operation of the aircraft.

2- A passenger /crew on board (such as a medical emergency).

It is usually a forced diversion to the nearest or most suitable airport or airbase, in which air traffic control must prioritize and give way immediately upon the declaration of the emergency.

Of course, during aircraft design, they take into consideration the redundancy for all vital systems, for example almost all commercial aircraft has 3 hydraulic systems with 3 or more independent pressure pump source with independent feed and return pipes , also the hydraulic pump types redundancy ,you can find EDP (Engine Driven Pump) and electrical pump as redundancy in same hydraulic system , in some hydraulic systems designs you can find PTU (Power Transfer Unit) to pressurize hydraulic system from other hydraulic system as redundancy

What are Emergency Landing Causes?

There are many causes for emergency landing, for example and not limited to:

• Emergency medical for any of human been on board.
• Engine failures.
• Major failure in any system may affect directly / indirectly on aircraft safety (hydraulic system, pneumatic system, fuel system…)
• Structure damage (like what may happen as a result of bird strike or lightning strike).
• Tire burst.
• Partial or complete failure in cabin pressure.
• Smoke or fire (after proper action to fir extinguish and eliminate the smoke)

What are the Types of Emergency Landing?

1. Forced landing: the aircraft is forced to make a landing due to technical problems. Landing as soon as possible is a priority, no matter where, since a major system failure has occurred or is imminent. It is caused by the failure of or damage to vital systems such as engines, hydraulics, or landing gear, and so a landing must be attempted where a runway is needed but none is available. The pilot is essentially trying to get the aircraft on the ground in a way which minimizes the possibility of injury or death to the people aboard. This means that the forced landing may even occur when the aircraft is still flyable, in order to prevent a crash or ditching situation.
2. Precautionary landing: may result from a planned landing at a location about which information is limited, from unanticipated changes during the flight, or from abnormal or even emergency situations. This may be as a result of problems with the aircraft, or a medical or police emergency. The sooner a pilot locates and inspects a potential landing site, the less the chance of additional limitations being imposed by worsening aircraft conditions, deteriorating weather, or other factors.
3. Ditching: is the same as a forced landing, only on water. After the disabled aircraft contacts the surface of the water, the aircraft will most likely sink if it is not designed to float, although it may float for hours, depending on damage.

The FAA does not require commercial pilots to train to ditch but airline cabin personnel must train on the evacuation process. In addition, the FAA implemented rules under which circumstances (kind of operator, number of passengers, weight, route) an aircraft has to carry emergency equipment including floating devices such as life jackets and life rafts.

Some aircraft are designed with the possibility of a water landing in mind. Airbus aircraft, for example, feature a "ditching button" which, if pressed, closes valves and openings underneath the aircraft, including the outflow valve, the air inlet for the emergency RAT, the avionics inlet, the extract valve, and the flow control valve. It is meant to slow flooding in a water landing

How often Emergency Landing happen?

The good news is that large aircrafts have multiple engines and redundant systems, so emergency landings are extremely rare for them, but even that some notable ones have occurred.

As a result of neat aviation accident investigations and corrective / preventive actions taken by the authorities in form of AD’s issuance, the traveling by airplane are the safest traveling method today.

As 2016 statistics, there were only 185 emergency landings total in the domestic U.S. out of an estimated 9.7 million flights — all of which concluded without incident. That's a nerves-alleviating 0.00002 % chance of having an emergency landing.

Who is responsible for aviation accident investigations?

“The State of Occurrence shall institute an investigation into the circumstances of the accident and be responsible for the conduct of the investigation, but it may delegate the whole or any part of the conducting of such investigation to another State by mutual arrangement and consent. In any event the State of Occurrence shall use every means to facilitate the investigation.” ICAO annex 13- CHAPTER 5. INVESTIGATION RESPONSIBILITY FOR INSTITUTING AND CONDUCTING THE INVESTIGATION

Of course, you will find more details in above reference as it may differ according to circumstances like the accident / incident locations.

Finally , if you want add extra information ,question or query we like to hear in the below comment

May be first time you hear about “aircraft technical record” it might seem obvious, but in this article we tried to uncover a set of rules and regulations which describes what we mean by “Aircraft technical Records” or “aircraft continuing airworthiness records”

Please at any circumstances don’t underestimate the importance of the technical records, without documentary evidence supporting the airworthiness status of the aircraft simply it would not be allowed to fly (in fact if the aircraft continuing airworthiness technical records were not available then the certificate of Airworthiness would be also be declared invalid!)- and ofcourse the aircraft not airworthy.

Regulatory definitions:

            EASA definitions:

“Detailed maintenance records” are required to be kept by an AMO (respectively Part-M/F organization or Part-145 organization). Maintenance organizations are required to retain all detailed records in order to be able to demonstrate that they maintained aircraft and components in compliance with applicable requirements. as defined in M.A.614 or 145.A.55(c)

“Detailed maintenance records”: are those records, coming from the AMO having performed maintenance, required to be kept by the owner/operator (or the CAMO when required by M.A.201) allowing to determine the aircraft configuration, the airworthiness status of the aircraft and all components installed, as well as to plan future maintenance as required by the AMP, based on the last accomplishment. as defined in M.A.305(h)

What the tasks required from “Technical record department”?

1. a) Maintain and manage any records associated with the maintenance management or operation (track hour /cycle /calendar to aircraft /engine/units/ components).
2. b) Liaise with the Stores inspector regarding the management of components and the control of Form 1’s for fitted components.
3. c) Raise, Issue and Distribute end of month status and engineering reports.
4. d) Liaison with Maintenance Planning and Engineering Departments in particular in respect of component configuration and status.
5. e) Support the performance of Airworthiness Reviews (ARC) process to ensure correct availability of back to birth records for Continuing Airworthiness.
6. d) Importation and Exportation of Aircraft Technical Records as required.
7. e) Perform QC Data checks of the various information’s which managed by the Technical records office and resolve any ambiguities, technical or other problems from Engineering, Operations and Crew.
8. f) General and administrative support to Engineering for additional support tasks for example management of Calibration and or servicing records of Ground Support Equipment (GSE)
9. g) Support for the Quality Department to track and manage Licensed Aircraft Maintenance Engineers Licenses (LAME) and Organization Company Approval as appropriate.
10. h) Perform Training and Mentoring to Technical Records support staff and junior administration staff regarding the correct functioning of the organization’s procedures.

Record keeping / Retention:

It is considered a best practice as part of the AMO record-keeping system, (and it is also required by certain competent authorities) to record information (e.g. batch number or other tracking reference) relevant to the identification of all standard parts and material used during any maintenance. This practice may limit safety and industrial risks in the case where a batch is recalled by the manufacturer. Such record does not need to be transmitted to the owner/operator/CAMO. See below figure

Finally, we in digital world, so it’s preferable to use digital software for all record. the software record system has many benefits than old fashion record (paper record), it gives you more control, ease the tracking process, searchable, can make better decision by making data analysis easily and ton of other benefits than paper record.

References:

           1- EASA.

           2-SOFEMA

Finally , if you want add extra information ,question or query we like to hear in the below comment

In this article we try to simplify the science answer the question: how airplane fly?

What are the forces affect airplane during flight?

There are 4 main forces on object during flight they are:

• Thrust: is the force that propels a flying machine in the direction of motion. Engines produce thrust.
• Drag: is the force that acts opposite to the direction of motion. Drag is caused by friction and differences in air pressure.
• Weight: is the force of gravity. It acts in a downward direction—toward the center of the Earth.
• Lift: is the force that acts at a right angle to the direction of motion through the air. Lift is created by differences in air pressure.

Simply, what is the secret makes the airplane fly?

If we try to put the answer in simple form, we can say: as a result of engine thrust the air flows across the wing and because of special shape of the wing (the airfoil shape) it generates enough lift force to carry the airplane

Reference:

• https://www.grc.nasa.gov/
• https://www.jaescompany.com/

If you have any question or query, we'd like to help, just leave us comment here and we will back to you with the answer.

After the success of three generations of the narrow-body aircraft B737, Boeing 737 MAX is designed and produced by Boeing Commercial Airplanes as the fourth generation of the Boeing 737, succeeding in the Boeing 737 Next Generation (NG).

This 737 series was publicly announced on August 30, 2011. The first 737 MAX airplane, named The Spirit of Renton, performed its first flight on January 29, 2016. The 737 MAX series gained FAA certification on March 8, 2017. The first delivery was a MAX 8 on May 6, 2017, to Malindo Air, which placed the aircraft into service on May 22, 2017. The 737 MAX is based on earlier 737 designs, re-engined with more efficient CFM International LEAP-1B engines, aerodynamic changes (including distinctive split-tip winglets), and airframe modifications.

According to Boeing website “The 737 MAX is the fastest-selling airplane in Boeing history with about 5,000 orders from more than 100 customers worldwide”

What's different about the Max?

Compared with previous 737 versions, the Max 8 has bigger, more powerful and more efficient CFM LEAP engines (more on those in a minute), improved aerodynamics and a redesigned cabin interior. It also can fly farther and carry more people than the previous generation of 737s, like the 737-800 and 737-900.

Lion Air Flight 610 crash

On October 29, 2018, Lion Air Flight 610, 737 MAX 8 registration PK-LQP, plunged into the Java Sea 13 minutes after takeoff from Soekarno–Hatta International Airport, Jakarta, Indonesia. The flight was a scheduled domestic flight to Depati Amir Airport, Pangkal Pinang, Indonesia. All 189 onboard died. This was the first fatal aviation accident and first hull loss of a 737 MAX. The aircraft had been delivered to Lion Air two months earlier. People familiar with the investigation reported that during a flight piloted by a different crew on the day before the crash, the same aircraft experienced a similar malfunction but an extra pilot sitting in the cockpit jumpseat correctly diagnosed the problem and told the crew how to disable the flight-control system. Following the Lion Air crash, Boeing issued operational manual guidance, advising airlines on how to address erroneous cockpit readings. The accident is under investigation with the final report expected to be released between August and September 2019.

Ethiopian Airlines Flight 302 crash

On March 10, 2019, Ethiopian Airlines Flight 302, 737 MAX 8 registration ET-AVJ, crashed approximately six minutes after takeoff from Addis Ababa, Ethiopia, on a scheduled flight to Nairobi, Kenya, killing all 149 passengers and 8 crew members on board. The aircraft was four months old at the time. The cause of the crash is unclear as of March 19, 2019, though the aircraft's vertical speed after takeoff was reported to be unstable. Evidence retrieved on the crash site suggests that, at the time of the crash, the aircraft was configured to dive, similar to Lion Air Flight 610. According to Ethiopian transport minister Dagmawit Moges, on April 4, the crew "performed all the procedures repeatedly provided by the manufacturer but was not able to control the aircraft". On May 21, CNBC reported that according to a person familiar with the matter, U.S. aviation officials believe a bird strike may have led to the crash of ET302. Boeing's shares rose in response to this information. The subsequent findings in the Ethiopian Airlines crash and the Lion Air crash led to the Boeing 737 MAX groundings across the world.

Accidents and incidents

In the two years of the 737 MAX's commercial service prior to its grounding, the global fleet of nearly 400 aircraft flew 500,000 flights and suffered two hull loss incidents. According to a statistical metric gathered on March 11, 2019, the 737 MAX's accident rate was second behind the Concorde, with four accidents per million flights, compared to the 737 Next Generation's 0.2 accidents per million flights.

On April 29, Boeing CEO Dennis Muilenburg stated that the aircraft involved were "properly designed" and that the crashes were caused in part by flight crew not fully following procedures that they were provided. On April 4, Muilenburg had said "It's our responsibility to eliminate this risk. We own it and we know how to do it.”

On May 14, reports surfaced of meetings between American Airlines pilots and Boeing executives before the Ethiopian Airlines crash, where the pilots asked Boeing to work urgently on a fix of the MCAS software. The FAA had already issued one directive after the Lion Air crash, instructing airlines to revise their flight manuals to include information on how to respond to a malfunction of the anti-stall system known as MCAS. In a closed-door meeting pilots and pilot union representatives argued that Boeing should push authorities to take an emergency measure that would likely had resulted in the grounding of the Max, including changes to the MCAS, while Boeing executives resisted. Mike Sinnet, Boeing Vice President present at the meeting, said he felt confident that pilots had adequate training to deal with a problem, especially now that pilots — who were not initially informed about existence of the new MCAS system — were aware of it. The pilots expressed frustration that Boeing did not inform them about the new software on the plane until after the Lion Air crash. "These guys didn’t even know the damn system was on the airplane, nor did anybody else," said Michael Michaelis, the union’s head of safety at the meeting. Mr. Sinnett said in the meeting. "The worst thing that can ever happen is a tragedy like this, and the even worse thing would be another one."

On May 18, 2019, Boeing admitted that flaws in 737 MAX simulator software made the system unable to reproduce flight conditions that contributed to the crashes in Ethiopia and Indonesia.

B737 Max Grounding

Ethiopian Airlines grounded its fleet on March 10. The Civil Aviation Administration of China ordered all MAX aircraft grounded in the country on March 11, stating its zero-tolerance policy and the similarities of the crashes. Most other regulators and airlines individually grounded their fleets in the next two days.

On March 11, the FAA issued a Continued Airworthiness Notification to the International Community (CANIC) for operators. The CANIC listed the activities the FAA had completed after the Lion Air accident in support of continued operations of the MAX.

On March 13, Canada received new information suggesting the similarity between the crashes in Ethiopia and Indonesia. Canadian Transport Minister Marc Garneau informed U.S. Transportation Secretary Elaine Chao of his decision to ground the aircraft. Hours later, President Trump announced U.S. groundings, following consultation among Chao, acting FAA administrator Daniel Elwell and Boeing CEO Dennis Muilenburg. The FAA issued an official grounding order, citing the new evidence and acknowledging the "possibility of a shared cause for the two incidents". The U.S., Canadian, and Chinese regulators oversee a combined fleet of 196 aircraft, nearly half of all 387 airplanes delivered.

What went wrong to cause these tragedies?

According to BBC News “Pilots of the crashed Ethiopian Airlines Boeing 737 Max were unable to prevent the plane repeatedly nosediving despite following procedures, an initial report has found.

The captain and first officer followed safety procedures recommended by Boeing. But they couldn't stop the aircraft going into a fatal dive shortly after takeoff from Addis Ababa on 10 March, the report by Ethiopian investigators said. All 157 people on board were killed.”

“The preliminary report into the accident, by Ethiopia's Aircraft Accident Investigation Bureau, said the plane's take-off appeared normal.

However, a short time later two sensors that measured the angle of the plane's flight began to record different reading”

What is the system under question?

The report did not attribute blame for the crash, but a detailed timeline suggests the pilots were struggling to deal with an automated safety system - known as the Maneuvering Characteristics Augmentation System (MCAS).

The system is designed to prevent the plane stalling when making steep turns under manual control.

How long is the 737 Max grounded for?

References:

• Boeing Website
• BBC News
• C-NET

Introduction

Rolls Royce Trent 1000 engines are known to be installed on, but not limited to, Boeing 787 aeroplanes, according to Rolls Royce these engines are “Optimized specifically to power the Boeing 787 Dreamliner family of aircraft, it draws on the technology and experience of four previous generations of Trent engines.”

RR Trent 1000 is 3 shaft high by pass ratio, axial turbofan with low, intermediate and high pressure compressor driven by separate turbines through coaxial shafts, with :

• the highest bypass ratio of any Trent engine 10:1,
•  20% More fuel efficient than the 767 that the Trent 1000-powered 787 replaces,
• 99.9% Dispatch reliability since EIS,
• Least environmental impact,
• Bleedless design

Challenges faces Trent 1000 engines

1. Several Dreamliner operators have reported corrosion-related fatigue cracking with the Trent 1000 Package C engines’ intermediate-pressure turbine (IPT) blades, defects that may result in engine failure. The issue has led to increased rates of inspection (reducing the inspection interval from 200 flights to 80 flights), which adds to maintenance costs and reduces aircraft availability.
2. Boeing reported to the FAA that the engine manufacturer recently determined that intermediate pressure compressor (IPC) stage 2 blades have a resonant frequency that is excited by the airflow conditions existing in the engine during operation at high thrust settings under certain temperature and altitude conditions.
3. EASA issue Airworthiness Directive AD #2018-0167R2 Intermediate Pressure Compressor Blades / Shafts – Inspection on Trent 1000-A, Trent 1000-AE, Trent 1000-C, Trent 1000-CE, Trent 1000-D, Trent 1000-E,Trent 1000-G, and Trent 1000-H engines, all serial numbers. These engines are known to be installed on, but not limited to, Boeing 787 aeroplanes. (Reference EASA AD #2018-0167Revision 2 effective16 October 2018).
4. After 3 superseded AD, EASA issue Airworthiness Directive AD #2018-0257 Intermediate Pressure Turbine Blades –Replacement (Reference EASA AD #2018-0257 effective 12 December 2018) on Trent 1000-A, Trent 1000-C, Trent 1000-D, Trent 1000-E, Trent 1000-G, Trent 1000-H, Trent 1000-AE, Trent 1000-CE, Trent 1000-A2, Trent 1000-C2, Trent 1000-D2, Trent 1000-E2, Trent 1000-G2, Trent 1000-H2, Trent 1000-J2, Trent 1000-K2, Trent 1000-L2, Trent 1000-AE2 and Trent 1000-CE2 engines, serial numbers (ESN) as listed in the AD, These engines are known to be installed on, but not limited to, Boeing 787 aeroplanes.
5. The US Federal Aviation Administration FAA has limited Dreamliners Model 787-8 and 787-9 airplanes, certificated in any category, powered by Rolls-Royce plc (RR) Trent 1000-A2, Trent 1000-AE2, Trent 1000-C2, Trent 1000-CE2, Trent 1000-D2, Trent 1000-E2, Trent 1000-G2, Trent 1000-H2, Trent 1000-J2, Trent 1000-K2, and Trent 1000-L2 turbofan engines to 140 minutes from the nearest airport instead of the 330 minutes they were originally certified for. (Reference: FAA Airworthiness Directive # 2018-08-03 effective April 17, 2018).
6. As Rolls Royce mention them self  :“As part of our ongoing inspection and testing of those engines we have decided to carry out additional engine inspections to those previously planned. The increased inspection frequency is driven by our further understanding of the durability of the Trent 1000 Package C compressor, a condition that we highlighted earlier this year. These inspections will be supported by service management and flight operations guidance to airlines to be issued by the airworthiness authorities. This will unfortunately lead to additional disruption for our customers. There are 380 Package C engines currently in-service with airlines. This new regime does not impact Trent 1000 Package B engines or Trent 1000 TEN engines.”

References:

• Rolls Royce website
• EASA
• FAA

“It is not possible to manage what you cannot control and you cannot control what you cannot measure!”

Key Performance Indicators

Definition

Key performance indicators (KPI) are a set of quantifiable measures uses to gauge the performance over time. These metrics are used to determine a company's progress in achieving its strategic and operational goals, and also to compare a company's finances and performance against other businesses within its industry.

• Performance measurement is a fundamental principle of management.
• The measurement of performance is important because it identifies current performance gaps between current and desired performance and provides indication of progress towards closing the gaps.
• Carefully selected key performance indicators identify precisely where to take action to improve performance.

What makes a KPI effective?

• Powerful form of communications.
• Demonstrate business data in easy to understand and clear way.
• Make decisions more clear and based on data.
• Help you to evaluate the success.
• Give you a broad understanding of your business’s current position.
• Show your progress towards key goals.

Always use SMART objective when thinking KPI

The letters are typically taken to stand for Specific, Measurable, Achievable, Relevant, Time-bound. In other words ask yourself these questions before start:

• Is your objective Specific?
• Can you Measure progress towards that goal?
• Is the goal realistically Attainable?
• How Relevant is the goal to your organization?
• What is the Time-frame for achieving this goal?

Also the KPI objectives must be DUMB: Doable. Understandable. Manageable. Beneficial.”

Types of KPIs

There are many types of KPIs that you can use . The common thread is that all of these are objectives and you should use the ones that make most sense for your business strategy. Types of KPIs include:

• Quantitative indicators that can be presented with a number.
• Qualitative indicators that can’t be presented as a number.
• Leading indicators that can predict the outcome of a process
• Lagging indicators that present the success or failure post hoc
• Input indicators that measure the amount of resources consumed during the generation of the outcome
• Process indicators that represent the efficiency or the productivity of the process
• Output indicators that reflect the outcome or results of the process activities
• Practical indicators that interface with existing company processes.
• Directional indicators specifying whether or not an organization is getting better.
• Actionable indicators are sufficiently in an organization’s control to effect change.
• Financial indicators used in performance measurement and when looking at an operating index.

How to define a KPI

Defining key performance indicators can be tricky business. The operative word in KPI is “key” because every KPI should related to a specific business outcome with a performance measure. KPIs are often confused with business metrics. Although often used in the same spirit, KPIs need to be defined according to critical or core business objectives. Follow these steps when defining a KPI :

1. Find a desired objective for the business.
2. Dissect the steps you need to take to reach that goal. 
3. List the data you need to monitor to track your progress towards that goal. 
4. Keep your strategy on check: come back to and observe the evolution of each stream of data at a fixed frequency. 
5. Focus on indicators/parameters that aid in improving results.
6. Understand the required metrics to enable better learning.
7. The KPIs need to be simple but be able to provide timely information.
8. Should be correlated and aligned with the objectives of the company.

Introduction

Cases of fuel spillage have been reported to Airbus on A320 family aircraft equipped with fuel transfer jet-pumps in the center tank.

This article recalls the protections available against tank overfill. It explains why fuel spillage happened on the reported events and provides recommendations on how to avoid it.

OVERFILL AND OVERFLOW PROTECTION AND MONITORING

Fuel tanks on Airbus aircraft are designed so that fuel spills into the vent tank through their vent line in the event of a tank overfill. Each vent tank is equipped with a NACA duct where fuel can flow out and onto the ground if the vent tank is full.

Refuel valves automatic closure

On A320 family aircraft, the refuel valve for a fuel tank will automatically close when the targeted fuel quantity is reached, or fuel is detected by the high-level sensor fitted in the tank during refueling.

Protection is available to prevent fuel spill incidents from Airbus aircraft during refueling. Sensors fitted to the center tank and wing tanks will automatically close the refuel valves to stop the refueling operation, preventing overfill. Fuel spills are avoided if these protections are operating correctly and this should be checked by a quick test just before refueling the aircraft.

Fuel spillages were reported to Airbus on A320 family aircraft fitted with transfer jet pumps where the fuel transfer mode selection was mistakenly left in MANUAL. Ensuring that the FUEL MODE SELector is set to AUTO before refueling the aircraft will avoid a fuel spill incident.

WHAT TO DO IN THE CASE OF A FUEL SPILLAGE?

In the event of fuel spillage, Airbus recommends the following actions:

1. Perform TSM Task “Refuel - Fuel Spillage From NACA Vent During Refuel’ to identify the root cause of the spillage
2. Notify Airbus about the fuel spillage event and provide the following information:
                   a. Fuel Spillage Sheet (available in the TSM task)
                   b. Fault Reports
                   c. Shop Reports of replaced components if any, including Part Number and Serial Number.

The environmental impact of aircraft carbon footprint is of rising importance to all operators as consumer demand for air travel continues to grow. The aviation industry holds a small contribution to global emissions, but unequivocally, it is one of the fastest growing contributors to emissions. Since the 1970s, when the price of aviation fuel began to spiral upward, airlines and aircraft manufacturers have explored many ways to reduce fuel consumption by improving the operating efficiency of their aircraft. Fuel economy concerns have been particularly important for operators of commercial aircraft, which typically fly many hours per day in competitive markets. Hence, there are also economic incentives for reducing emissions, since reduced emissions are naturally related to reduced fuel consumption and savings in fuel expenditure for air carriers.  A great potential source for fuel savings is reducing parasitic drag of the airframe, such as inherent wingtip vortices.

Introduction to Wingtip Vortices

Wingtip vortices are schematically illustrated in Figure 1. If a wing is producing lift, a pressure differential will exist between the upper and lower surfaces, i.e. for positive lift, the static pressure on the upper surface will be less than on the lower surface. At the tips of the wing, the existence of this pressure differential creates a vortex where the high-pressure air below the wing can escape to the low-pressure area above the wing to form a swirling tunnel of turbulent air along (top of Figure 1) and behind the wing (bottom of Figure 1)The vortex is strongest when the angle of attack is high, such as during take-off and landing, because the pressure differential at high angles of attack is greatest during these phases.

Figure 1: Wingtip Vortices [2].

Why are wingtip vortices detrimental to aircraft aerodynamics?

To create a specific lift coefficient with the airfoil section, a certain angle of attack must exist between the airfoil chord line and the relative wind; see Figure 2. However, as the total lift force is developed perpendicular to the wing chord line, it is angled slightly backwards. There are two problems occurring here; firstly, some of the total lift force is now deflected backwards leading to the creation of lift-induced drag, illustrated in Figure 2; and secondly, there is a smaller component of lift pointing upwards to counterbalance the weight of the aircraft. Both of these effects are to the detriment of the lift-to-drag ratio, a key efficiency parameter in aircraft design. Thus, as a result of this decrease in vertical lift, the wing must be given an angle of attack greater than the section angle in order to generate more lift to account for the inclination of the total lift force. However, any increase in the angle of attack also increases the lift-induced drag. Wingtip vortices exacerbate this lift-induced drag by causing the total lift force to point even further backward A number of possible solutions exist for mitigating the effect of vortex-induced drag, but conventionally, wingtip retrofits, commonly known as winglets, are used to mitigate the problem.

Figure 2: Lift-Induced drag.

How do winglets help to improve the situation and what are some of the drawbacks?

One of the visible actions taken by commercial airframe manufacturers to reduce wingtip vortices is the modification of an aircraft’s wingtip by installing, as shown in Figure 3, near-vertical “winglets”. Experience shows that these tip devices reduce block fuel consumption (total fuel burn from engine start at the beginning of a flight to engine shutdown at the end of the flight) of the modified aircraft by 3% – 5%, depending on trip length [1].

Figure 3: Vortex intensity with and without winglets [3].

Winglets are airfoil-shaped structures that also produce lift but are orientated inwards towards the fuselage relative to the rest of the wing. The presence of winglets changes the effect that wingtip vortices have on lift and drag. The winglets cause the relative wind to bend inwards towards the fuselage, creating a forward vector of lift in the direction of flight counteracting some of the induced drag, as illustrated in Figure 4.

Figure 4: Creation of forward lift force to partially alleviate induced drag [4]

However, winglets do not operate effectively under all conditions throughout the flight envelope and incur an added mass penalty. So, the question is whether winglets conserve more fuel by reducing drag than the extra fuel required to carry their mass. An inherent problem with winglets is their susceptibility to flutter and increased bending stresses in the winglet fold area. In fact, under some flight conditions an equal area, flat span extension can be a more effective and less risky design solution. Lastly, winglets are always present in flight, as they are fixed devices attached to the tips of wings, and because they are fixed surfaces, they provide their best lift-induced drag reduction for a single design point. Hence, a more on-demand and active, rather than passive, type of control device could be of benefit. One example is the use of a “Fluidic Winglet”.

What is a fluidic winglet and how do they work?

A fluidic winglet is a system architecture that can provide a controlled stream of air ejected outwards in the vicinity of the wingtip, as shown in Figure 5, to create an aerodynamic force strong enough to disrupt the vortex formation. This system architecture could potentially produce the same benefits as a winglet without a visible increase in wingspan.

Figure 5: Wing with fluidic winglet.

The pressurized air for the fluidic winglet could be taken from: 

1. The jet engine
2. The aircraft surface
3. The leading edge of the wing
4. An internal pressurised air tank

RAM drag (a common source of system-induced drag caused by taking in air, typically for cooling purposes) and weight penalties introduced from the above systems must be considered when evaluating the system. If air is taken from the aircraft surface, then a Laminar Flow Control (LFC), a Hybrid Laminar Flow Control (HLFC) system, or a duct located at the wing leading edge stagnation pressure line could be appropriate. However, this would not result in high jet momenta and will be limited to lower mass flow rates [5]. The LFC and HLFC systems are active boundary layer control techniques, shown in Figure 6, that help to maintain the laminar flow state by means of suction onto the wing surface during flow states that would otherwise be transitional or turbulent.

Figure 6: Laminarization of flow using LFC and HLFC system [6].

If the air used to operate the fluidic winglet is taken from a separate pressurised tank inside the fuselage, the fluidic system could look something like depicted in Figure 7. Once the pilot signal is received, a solenoid valve allows the air to be released from the tank where it is regulated to provide the required exit velocity. The air then flows into the vortex dissipation device where the air is distributed to the discharge nozzles. If the exit pressure past the pressure regulating valve (PRV) exceeds the design limit, a shut-off valve ahead of the PRV will not allow fluid to pass above a certain set pressure as a fail-safe.

Figure 7: Potential fluidic system architecture.

Analysis – What potential benefits of the fluidic winglet can be deduced over conventional alternatives?

In order to deduce the potential benefits of the fluidic winglet, the lift coefficient (C_L), drag coefficient (C_D) and lift-to-drag ratio (C_L/C_D) of three models are investigated using ANSYS Fluent, and the results are extracted and summarised in Figure 8. The models designed are:

1. A clean wing (CW) with no winglet attached: designed from a NASA HSNLF (1)-0213 airfoil with a leading-edge sweep angle of 33° and a taper ratio of 0.4.
2. A wing with a raked winglet (WRW): designed from a NACA 0012 airfoil with 10% of wing semi-span and a taper ratio of 0.2 and with a sweep angle greater than that of the wing of about 57°.
3. A wing with the fluidic winglet (WFW): this will not require a wingtip extension and hence, there is no physical increase in the wing’s span. The fluidic winglet instead consists of a rectangular high-aspect ratio slot.

Note: The models do not have an aerodynamic twist consideration.

The boundary conditions that constitute the flow variables are: a freestream velocity of 50 m/s and an injection velocity three times the freestream (150 m/s) with a jet sweep angle equivalent to that of the wing sweep (i.e. the jet is colinear with the wing). These models will be tested at high angles of attack of 7.5°, 10° and 12.5° to simulate the effect of the fluidic winglet on the vortex when it is strongest.

Figure 8: a) Lift coefficient improvement with addition of raked and fluidic winglet b) Drag coefficient improvement with addition of raked and fluidic winglet c) lift-to-drag ratio improvement with addition of raked and fluidic winglet.

As illustrated in Figure 8c), the results indicate that having a tapered wingtip extension (i.e. a raked wingtip, WRW) provides an improved aerodynamic efficiency (C_L/C_D) of 7% for an angle of attack of 10°, and generally better levels of drag reduction are expected at low angles of attack. As shown in Figure 8a), the WRW improves the lift coefficient much more than the fluidic wingtip (WFW). This is due to the increase in wing area added by the physical wingtip. However, this additional surface area causes a parasitic component of drag, which is why the WFW outperforms the WRW design in terms of drag coefficient, see Figure 8b). Further, in Figure 8c) it appears that the WRW’s performance is reduced by 16% at an angle of attack of 12.5°, which occurs due to local wingtip stall. There are two reasons for this occurrence; firstly, the dissimilarity between the main wing airfoil and the raked winglet airfoil and secondly, the WRW is not twisted. The WRW should employ twist to avoid local stalling at such high angles of attack.

Similarly, the application of the WFW at high angles of attack leads to improvements to the wing’s aerodynamic efficiency. As shown in Figure 8c), at 7.5° angle of attack, the lift-to-drag ratio is increased by 2.5%, and at 10°, the lift-to-drag ratio is increased by 6.5%. However, for the 12.5° angle of attack, when the 50 m/s freestream air collides with the 150 m/s jet, stalling occurs locally, thus spoiling the lift and increasing drag. The stall occurs due to a local increase in the Reynolds number in the region where the freestream and jet efflux meet.

Nonetheless, because the fluidic winglet has no additional surface exposed, there is no increase in parasitic drag. This fact contributes to acceptable drag reductions as shown in Figure 8b). Hence, the overall enhancement of the lift-to-drag ratio between the WRW and the WFW is very similar emphasizing the capability of the WFW. Even though the WRW is more effective at improving the lift, the WFW is better at reducing drag without compromising lift; can be activated at a specific angle of attack; and has the potential to deliver better levels of drag reduction at more than a single design point during the flight envelope. Other benefits not only include potential improved fuel economy but also improved payload-range capability, improved take-off performance, and less take-off noise.

How is the fluidic winglet able to improve the lift-to-drag ratio?

The WFW is able to improve aerodynamic efficiency by altering the chordwise lift distribution along the wingspan. It is observed that, at high angles of attack, the sectional chordwise pressure distribution on the upper and lower surface of the WFW changes favourably from root to tip. This can be seen more clearly using Figure 9 where the sectional lift force on discrete sections along the wing is estimated using Equation 1, where P_L is the wing’s lower surface pressure, P_U is the pressure on the wing’s upper surface and S is the wing area.

Figure 9: Spanwise lift distribution over CW (Left) and WFW (Right).

The spanwise variation in the sectional lift force, as shown in Figure 9, for the CW is observed to increase until the 80% wing semi-span location, at which point it drops off dramatically. This drop off in lift force towards the wingtip (100% wing semi-span position) is due to the creation of wingtip vortices that disrupt effective lift generation over the wing. It is clear that the aerodynamic lift force is considerably increased by the WFW towards the wingtip for the 7.5° and 10° conditions, thereby demonstrating the effectiveness of the jet efflux to increase the aerodynamic loading at the wingtips for the angles of attack tested herein. The only exception is the 12.5° angle of attack condition where the addition of the efflux creates a local stall condition, as previously discussed

Additional thoughts – How could fluidic winglets be implemented?

It is important to evaluate aircraft inventory and identify the most suitable aircraft candidates for fluidic winglet modification. The process could be summarised under four main tasks:

1. Examine the feasibility of modifying aircraft with fluidic winglets, to include a cost-effectiveness analysis of the modification in net present value (NPV) terms.
2. Determine the market price of aviation fuel at which incorporating the fluidic winglets would be beneficial for each platform.
3. Consider impact to aircraft maintenance and flight operations (including ground operations).
4. Investment strategies to minimize the operator’s capital investment and maximize investment return.

These tasks call for a quantitative assessment of the costs and benefits of fluidic winglet modifications on a variety of platforms. In a comprehensive analysis, one would need to include the non-recurring engineering costs of wing analysis and fluidic system design, as well as the costs of materials, manpower, and out-of-service time to accomplish the modification, financial implications, training costs, potential impacts on maintenance docks, costs associated with software and technical manual revisions, and any impacts on maintenance, operations, or mission accomplishment.

In each case, the aircraft structure needs to be studied and determined to be appropriate; engineering design must be analysed in detail; modifications will need to be prototyped, tested, and certified; modification kits to be developed and flight manuals revised as required. Past commercial experience with aircraft that have installed conventional winglets has shown that there have been no significant impacts on aircraft maintenance, flight operations, or ground operations (gate space, taxiways, hangars, etc.) [1].

Conclusion

It is clear that aerodynamic improvements, including fluidic winglets, can make significant contributions to the efficiency of aircraft. In each case, however, the appropriateness of such structural/system modifications must be determined fleet by fleet. These decisions are very complex and will depend on many factors, including the design of the aircraft’s structures, systems design, design margin within those structures, the condition of the structures, mission profiles, utilization rates, fuel consumption rates, fuel prices, and the remaining life of the aircraft. There are also other ways to reduce fuel consumption, many of which have already been adopted by commercial airlines. Nonetheless, the best solution is decided by economics rather than aerodynamics.

The design of the fluidic winglet combines several disciplines such as structures, manufacturing and assembly, systems, aerodynamic and flight dynamics. The selection of the most appropriate system air resource and subsequent system design will depend upon the jet efflux requirements of the fluidic winglet. The benefits of the concept are highly dependent upon the jet parameters like the jet momentum coefficient, jet dihedral, jet sweep, jet thickness and jet area as well as the boundary conditions. Higher jet momenta and smaller jet cross-sectional areas show promise to move the vortex centre further away from the wingtip to increase the effective wingspan. Jet sweep angles higher than the wing sweep angle are not suspected to provide improved results.

Since 2010, BAE Systems has set out to develop key technologies and skills with long-term collaboration from academia, industry and the UK government to create the combat air system of the future so that the UK can deliver more advanced capabilities through shared investment and revolutionise aircraft design. The first ever exhibit of fluidic flight control (i.e. no flaps, elevators or ailerons) begins with the FLAVIIR Demon Project (Flapless Air Vehicle Integrated Industrial Research program), a UAV showcasing new technology for the conventional flight control system. There are slots located on the wing’s trailing edge for the blown compressed air taken from the APU (Auxiliary Power Unit) to be curled either upwards (i.e. lowering the wing) or downwards (i.e. lifting the wing) to provide for control of the aircraft. This allows for a more seamlessly integrated design with fewer mechanically moving parts, and hence, a design with reduced edges and gaps that make the aircraft less observable on radar.

Figure 10: Flaviir demon project – a collaboration between BAE Systems and Cranfield University [7].

Similarly, in 2017 BAE Systems, in collaboration with the University of Manchester, revealed the first flight of MAGMA, a new UAV iteration showcasing novel control technologies for wing circulation control and fluidic thrust vectoring. The wing circulation control system takes air from the aircraft engine and blows it supersonically through the trailing edge of the wing to provide roll control for the aircraft. The fluidic thrust vectoring systems also uses blown air to deflect the main thrust allowing for the pitch direction of the aircraft to be changed. So far, flight tests have been promising and we are awaiting the first use of such circulation control in flight on gas turbine aircraft.

Figure 11: MAGMA project - a collaboration between BAE Systems and the University of Manchester [8].

References

[1] National Research Council. ASSESSMENT OF WINGTIP MODIFICATIONS TO INCREASE THE FUEL EFFICIENCY OF AIRCRAFT, accessed 10/01/2020

[2] Jeffrey (2008). Wingtip Vortices and Wake Turbulence Explained, accessed 10/01/2020

[3] Mike C (2017). WHAT AM I: WINGLETS, accessed 10/01/2020

[4] Colin C (2019). This Is How Winglets Work, accessed 10/01/2020

 [5] Ronald J (1998). Overview of Laminar Flow Control, NASA Technical Paper, accessed 10/01/2020

[6] Krishnan K (2017). Review of hybrid laminar flow control systems, accessed 10/01/2020

[7] Ben C (2010). DEMON UAV achieves historic first ‘flapless flight’, accessed 10/01/2020

[8] Andrea K (2019). MAGMA: The future of flight, BAE Systems, accessed 10/01/2020

and one of the most dangerous ways to spread COVID-19 around the world is traveling from place to place and of course the flight industry one of the most popular travel way across the countries.

Coronavirus symptoms

As CDC -Center of Disease Control and Prevention- “Reported illnesses have ranged from mild symptoms to severe illness and death for confirmed coronavirus disease 2019 (COVID-19) cases.

The following symptoms may appear 2-14 days after exposure.^*

• Fever
• Cough
• Shortness of breath”

COLOGNE, March 13, 2020 - The European Union Aviation Safety Agency (EASA) has issued a safety directive to reduce the risk of spread of the novel coronavirus through flights to and from high-risk areas. This is the first EU-wide operational measure to control the spread of COVID-19 in Europe

• Safety Directive 2020-01 effective date 23 March 2020 – which applicable on national Aviation Authorities (NAAs) responsible for the certification and oversight of aircraft
  operators involved in commercial air transport of passengers in accordance with Commission Regulation (EU) 965/2012
• Safety Directive 2020-02 effective date 23 March 2020- which applicable on Third Country Operators (TCOs) authorized by EASA pursuant to Commission Regulation (EU) No 452/2014 to perform commercial air transport of passengers into, within or out of the territory subject to the provisions of the Treaty on European Union.
• Annex 1 - attached to previous SD’s which contain a list of airports located in affected areas with a high risk of transmission of the CoViD-19 infection (This Annex is developed in coordination with EASA Member States and based on the information from WHO, ECDC, and other reputable public health institutes.)

Previous safety directive specifies measures to be taken for flights serving high-risk destinations. It mandates thorough disinfecting and cleaning of aircraft which operate from high-risk destinations after each flight. Exceptions can be made only when disinfectants with a longer-lasting effect are used – but even in those cases, thorough disinfection is mandated no later than 24 hours after departure from a high-risk airport.

Safety Objective(s) to be achieved:

To minimize the risks to passengers and to the general public, due to operations from airports
located in affected areas with high risk of transmission of the CoViD-19 infection by aircraft
operators certified in accordance with Commission Regulation (EU) 965/2012.

Recommended Corrective Action(s) to be taken:

(1) NAAs to ensure, by taking the appropriate national measures, that aircraft operators under
their oversight and involved in commercial air transport of passengers in accordance with
Commission Regulation (EU) 965/2012 from an airport located in an affected area with high risk
of transmission of the CoViD-19 infection:
(1.1) Clean and fully disinfect the aircraft using substances suitable for aviation use after each
flight coming from an airport located in an affected area with high risk of transmission of
the CoViD-19 infection (see Note 1 of this SD).
Note 1: Such as substances containing 62%-71% ethanol alcohol, 0.5% hydrogen peroxide, or
0.1% sodium hypochlorite. Suitability of the substances should be checked against the aircraft
manufacturers’ documentation.
The operator may implement different disinfection frequency based on a risk assessment
which takes into account the operational circumstances and the duration of the
disinfecting effects of the substance used. In such a case, the operator shall ensure that
the aircraft is fully cleaned and disinfected not later than 24 hours after the departure
from an airport located in an affected area with high risk of transmission of the CoViD-19
infection.
(1.2) Equip the aircraft with one or more Universal Precaution Kits. Such kits should be used to
protect crew members who are assisting potentially infectious cases of suspected
CoViD-19 and in cleaning up and correctly discarding any potentially infectious contents.
Information on the actions taken:
(2) NAAs shall take measures to achieve the determined safety objective within 7 days from the
the effective date of this Safety Directive and inform EASA of those measures

Update 10 Apr 2020

In response to the CoViD-19 world situation and to limit the spread of the disease and protect EASA staff, EASA decide to cancel all travels and external meetings, as EASA mentioned on the web site : "

EASA update on impact of CoVid-19 on its operations

In response to the CoViD-19 situation, EASA has taken measures to protect the health of its staff and limit the spread of the disease. This includes the cancellation of all travel and external meetings, which means that scheduled site visits and audits, for example, cannot take place as planned. The relevant staff are in contact with their counterparts in our stakeholder organisations to work together to manage this situation and ensure that no additional risks to aviation safety arise in these difficult times."

References:

• EASA
• CDC

In the automotive industry, electrification is developing at a fast rate. In the UK, both electric and hybrid cars are becoming a common sight on the roads, as well as electric charging ports in car parks. Electric vehicles offer a better solution towards a cleaner, greener environment than their diesel/petrol counterparts, as well as reducing noise pollution for those living in busy residential areas. So, when will air travel and air freight follow this electric journey?

Certainly, aircraft emissions degrade air quality and have an increasing effect on global warming as most emissions occur at high altitudes. According to the European Union (1), aviation accounts for approximately three percent of the EU’s total greenhouse gas emissions, and more than two percent of global emissions. Although air travel currently accounts for only a small portion of global emissions, air travel is recognized as one of the fastest growing contributors as elucidated in a recent study in the Atmospheric Chemistry and Physics journal. But by what mechanisms is aviation actually effecting the climate?

Aircraft engines do not only produce plenty of CO₂, but also exhaust nitrous oxides, NO_X, fine particulate matter, PM₂₅, and ozone, O₃. CO₂ emissions are the most significant contributor to climate change and have the same effect regardless of altitude emission. However, at higher altitudes, NO_X emissions are particularly effective in forming O₃, thereby causing a greater global warming effect than would be the case at lower altitudes.

To put this into perspective, if you’ve ever played with a Carbon Footprint Calculator and plugged in a return trip from London to New York, this trip balloons your carbon footprint by more than 2000 pounds of CO₂, nearly equivalent to the level of emissions incurred by heating an average European household for an entire year (2). Reducing the CO₂ impact of aircraft should be addressed as early on, as future regulations may impart even stricter regulations on environmental targets that will only be achieved by the use of the latest, and hence most expensive, technologies.

Hence, there is a clear incentive for cleaner, greener air mobility: the reduction of CO₂, NO_X, PM₂₅ and O₃ emissions, reduced noise and fuel consumption. Currently, we have reached a plateau in terms of improving aircraft fuel efficiency and reduced emissions. By introducing electric battery-powered aircraft, an opportunity exists to reduce potentially harmful emissions even further and to make air travel quieter for urban areas. But is electric flight actually possible given the technological challenges?

Many industry giants are playing their part to research and develop new prototypes and test concepts in electrification. Commercially, the Airbus A350 and Boeing 787 increasingly use battery power for several of their on-board systems to form an approach described as the ‘More-Electric Aircraft’ (MEA), whilst simultaneously developing methods for progression towards full electric propulsion. The strategy is to begin with a hybrid option first, with energy still provided by hydrocarbon fuels, and then progressing to an all-electric system with batteries to provide energy for propulsion.

In technical terms, the main critical challenge that projects like the Airbus E-Fan X, Zunum Aero, and Wright Electric are faced with is the power-to-weight ratio or specific power. Considering an all-electric system, a battery with greater energy density than those currently available, which are also effective, reliable and have a long life, are required. Historic trends and current understanding of aircraft development cycles suggest that battery technology will not be available until the 2030s to allow full incorporation at current aircraft scales.

Potential Propulsion System Architectures  

In the short term, we will probably witness a ‘More Electric-Hybrid’ commercially sized aircraft rather than an ‘All-Electric’ alternative. This ‘More Electric-Hybrid’ version could deliver real benefits through reduced emissions and allow for the development of motors and power electronics for the transition to fully electric operation. Let’s examine, on a system level, what a hybrid powered solution might look like.

Using the existing gas turbine, with traditional jet fuel (kerosene) mixed with biofuels, to drive an electric generator makes for an existing and well-understood solution. However, a new power electronics system is likely to be required to control and transfer the electrical energy to electric motors to provide thrust.

If batteries are used to power the remaining systems on the aircraft, we’ve got a ‘More Electric-Hybrid’ solution. The power available from the generator and batteries can be combined to power all aircraft systems to form a ‘Fully-Hybrid’ solution with each means of energy supply augmenting the other in different ratios during different flight phases. But, if kerosene is still the source of energy, then where does the reduction in emissions come from?

In this scenario, the aircraft’s flight is affected by the varying thrust requirements needed for take-off, climb, cruise, and altitude changes. Current jet engines are designed to operate in all conditions but do not always function optimally and efficiently in all cases. In a hybrid solution, the gas turbine could be isolated from changes in operational conditions and continuously run at an optimized speed to power an electric generator, which then drives the power electronics that provide electrical energy.

The main danger in this scenario is relying on unproven power distribution systems and electric motors. Indeed, one of the stated objectives of the Airbus E-Fan X program is to address this uncertainty with regards to electric power systems. Further advancements can be made by switching the kerosene-powered gas turbine and generator to battery power, thereby forming an ‘All-Electric’ system. In this case, the power electronics used for the hybrid solution will need to be adapted, but the propulsive element would not need to be changed.

A 50kg Electric Motor

Siemens developed a 50 kg electric motor SP260D that delivers 260 kW—five times more than comparable hybrid electric propulsion systems of equal weight. However, this is a long shot compared to the power required for a commercial aircraft to fly at acceptable speeds, typically in the order of two to fifty megawatts. Nonetheless, Siemens established its electric propulsion systems business through the development of the eAircraft program, now acquired by Rolls Royce.

So, with improved technology, can enough power be generated? Currently, the answer to this question isn’t clear, keeping in mind the overall aircraft weight, safety considerations for electrical systems, wiring routes, electrical interference, and the thermal environment created by batteries.

A High Aspect-ratio Wing Design

Aircraft wings are designed to withstand aerodynamic loads and carry jet fuel distributed across the span. For an electric aircraft, would there be any benefit of carrying batteries within the wings instead?

One positive side-effect of electrification would be that the wing's mass remains constant during flight (unless using lithium air batteries), creating novel opportunities for aeroelastic tailoring and aerodynamic optimization by allowing wings to become longer and thinner (better lift-to-drag ratio). A current challenge of designing long and slender wings for conventionally fueled is the onset of 'aeroelastic flutter', an unstable interaction between airflow and the wings elasticity causing buildup of oscillations and potential wing failure. With strategically placed batteries, thinner and longer wings could emerge as a viable design that doesn’t succumb to flutter, thereby improving aerodynamics and paving the way for radically different aircraft configurations.

The Need to Reduce Aircraft Mass

What happens to the weight of the airframe in a move towards hybrid or full electrification? In a hybrid system, the full propulsion and electrical system, combined with all the technical operation equipment inside the aircraft, will probably increase the mass of the airframe. Furthermore, as the aircraft is no longer shedding mass via fuel burn during flight, the landing weight of aircraft is likely to be higher than it is today. To compensate for these effects, reductions in the airframe mass are probably required to facilitate a fully electric system. Indeed, designing lighter airframes is a huge challenge, putting great requirements on future research on materials science to determine the full capabilities of next-generation metallic alloys and fiber-reinforced plastics. 

Funding Resources

The best solutions often come from coordinated efforts to ensure a collaborative, knowledge-sharing approach that leads to conformity in standards. The UK is a major player in Aerospace Research & Development and is involved in extensive research networks, partnerships, and bids to numerous funding bodies working on developing the technology for the future of air travel.

These funding bodies include the Engineering and Physical Sciences Research Council (EPSRC), as well as the Aerospace Technology Institute (ATI) established between industry and the government to develop the UK’s technology strategy through £3.9 billion of investment. Another influential body is the Air Transportation Systems Lab, which collaborates on research projects with the UK and overseas universities.

Lastly, the largest European research program developing innovative technologies aimed at aircraft emission and noise reductions, known as the Clean Sky Initiative, has a €4 billion budget and has backed several projects like Airbus’ BLADE and Safran’s Contra Rotating Open Rotor engine.

Regulation

There is a need for new regulations regarding the emerging technologies, platforms and systems related to electrification. Firstly, as new technologies are created in the field of electric aviation, each technology will need regulatory backing to determine the airworthiness of the technology. This is critical to establish broad regulatory acceptance for enabling technologies like high-power batteries, voltage distribution systems and boundary layer ingestion.

Subsequently, regulation will be critical to enable new platforms. Regulation and certification procedures for radically new architectures such as distributed fans will be required to enable the full potential of Electrical Propulsion. As a first step, both the Federal Aviation Administration (FAA) and the European Aviation Safety Agency (EASA) are currently opening doors for Electrical Propulsion. For example, a key change in FAA Part 23 and EASA CS23 came into effect in 2017, allowing larger classes of general aviation aircraft to legally fly non-traditional engine types. This not only opens revenue potential for developers in general aviation, but this platform category is a key stepping stone to even larger architectures. There is, however, a long journey ahead and regulation must keep a-pace with the technological evolution of electric aircraft.

In April 2018, these new regulations provided the opportunity for Siemens to test the Magnus eFusion at Matkópuszta airfield in Hungary, using a Siemens SP55D electric motor and a FlyEco diesel engine to allow for silent take-off and landing with an extended range. The full electrical propulsion system is developed by the Siemens eAircraft program. Furthermore, a Los Angeles-based company Ampaire recently demonstrated its electric hybrid propulsion system at Camarillo Airport in California with its maiden flight test in June 2019. Their technology was adapted to the Cessna 337 Skymaster and is already considered by some as the largest hybrid-electric aircraft to have ever flown.  

There’s Turbulence Ahead

Certainly, the biggest challenge is integration. For example, when designers and engineers have new technologies ready for flight, how does the industry support in-service operation? As an aviation company, how will business models need to adapt over the next twenty years? When is the best time to start thinking about how to integrate these new business models with the shift in aircraft architecture? Even though some of these changes are still years away, it pays to contemplate the disruptive nature of these changes now, and to consider strategies of how the industry can ready itself to face up to these coming challenges.

Additional Thoughts

Keeping in mind the potentially great opportunity aircraft electrification presents, Maintenance and Servicing Organizations (MRO’s) should be reconsidering their operations to address questions like what kind of physical infrastructure will be needed going forward? Topics for consideration range from how many spare batteries will need to be stored at airports and the most optimal location of recharging points to how long it will take for the batteries to be charged or changed in between flights. The latter will be a considerable consideration for airlines, as the aircraft will not be earning money when it is recharging. With regards to traffic control, what happens in the case of diversions and re-routing? Will regional electric aircraft take priority over long-range gas-powered aircraft? Or could quieter aircraft lead to additional airports in closer vicinity to cities, such that regional and long-range aircraft won’t share the same airspace? Finally, a major challenge will be instilling confidence in passengers about the safety of this new technology.

Conclusion – Where Do We Stand?

The continuing growth of the aviation sector has buoyed production rates and has led Airbus and Boeing to establish themselves as the key players in the aviation market. This duopoly has only been reinforced by recent mergers and acquisitions of smaller operations (Bombardier and Embraer). The shift to electrification poses a risk to incumbents as this new paradigm in propulsion levels the playing field for new entrants into the market.

However, both incumbents and new players face key technical barriers such as the current energy storage capacity per unit weight of batteries—500 Wh/kg is widely regarded as the minimum required for electric flight with commercially acceptable payload-range characteristics—as well as light and efficient electrical generators, motors and power electronics able to convert, condition and switch to high voltage power.

On the regulatory side, airworthiness authorities will have to find approaches to certify novel aircraft architectures as for over fifty years commercial aircraft have not deviated from the gas turbine powered architecture. The Advisory Council for Aeronautics Research (ACARE) has brought about a united sense of purpose across the European aviation sector to shift towards greener solutions and has set challenging goals, such as achieving seventy-five percent CO₂ emission reductions per passenger.

These challenges mean that we will probably witness a ‘More Electric-Hybrid’ commercially sized aircraft in the near future rather than an all-electric alternative. This could, however, still deliver real benefits through reduced emissions and allow for the development of motors and power electronics for the switch to fully electric operation in the far-reaching future.

Further Reading

• Aircraft Electrical Propulsion – The Next Chapter of Aviation?

References

1. https://ec.europa.eu/clima/policies/transport/aviation_en
2. https://www.independent.co.uk/environment/climate-change/your-carbon-footprint-revealed-climate-change-report-finds-we-each-produce-11-tons-of-carbon-a-year-427664.html
3. theicct.org/blogs/staff/overturning-conventional-wisdom-aircraft-efficiency-trends
4. Current and emerging trends in the aerospace sector - Atkins
5. https://www.slideshare.net/WSAtkins/electrification-of-aircraft-102581749
6. https://press.siemens.com/global/en/feature/electric-flight
7. https://www.pbs.org/wgbh/nova/article/morphing-wings/

Definition

A Service Bulletin SB is document released by manufacturers of product like aircraft, engines, APU, landing gear, appliance or any other components.

What is the purpose behind releasing SB?

The purpose of SB is to communicate with operators for details of modifications, new product release which can be embodied in aircraft.

Service Bulletin SB may issue by the manufacturer to:

• Fix safety issue (Mandatory & Alert SB)
• Avoid potential maintenance errors.
• Increase product reliability.
• Ease product maintenance ability.
• Add a new feature.
• Introduce a wholly new product exchange old one.
• Enhance aircraft, engine or any other product design.
• Enhance aircraft, engine or any other product performance.
• A modification which extend product life.

Service Bulletin SB document structure:

SB document structure may vary from manufacturer to another, but all SB should contain the main titles as it’s important to understand and comply with SB.

The main SB document structure:

• Effectivity:

In this section the manufacturer discus which aircraft, component, serial numbers or part numbers which will apply this SB on.

• Concurrent requirements
• Reason:

Discuss the reason of issuance, and the importance level of the SB also what the operator gain from complying with this SB

• Description:

General description of what to do to execute the service bulletin

• Compliance:

This section gives if required to execute the SB in a certain time frame, and if there are SB’s or AD’s in compliance with this SB

• Approval

This section discusses the approval level of the SB

• Manpower:

Manpower required to complete and execute the SB task in details

• Weight and balance changes:

Tell the operator if the aircraft weight will be affected by executing this SB.

• Material Information:

Discusses the material required availability, support information, parts necessary for each aircraft and prices.

• Tool and Kit Information

The tools, special tools and kits required to carry out the SB task

• Accomplishment Instructions:

Instruction needed to complete and carry out SB tasks including subtasks and job setup and preparation and may refer to Aircraft Maintenance Manual AMM or any other standard manual.

What are the categories/classifications /types of SB?

SB Category differs from manufacturer to another, but sometimes to standardize the engineering work and ease the decision-making process, the CAMO engineering put their category and classification with consistence with different manufacturer classifications.

If a service bulletin is not an alert service bulletin, mandatory or a bulletin referenced in an AD, it becomes optional and may or may not be incorporated by the operator.

Here will browse some of famous manufacturers service bulletin categories /classification/types:

· Boeing SB types:

Boeing classifies Service bulletin to two main types then under these two other types as you will see in below classification,

   a- Change Type:

           1)      Master Change.

           2)      Miscellaneous Retrofit.

           3)      Other.

          4)      Production Revision Record.

   b- Product Safety Type:

          1)      Alert.

          2)      Standard.

         3)      Unusually Significant.

Of course, the importance of safety type higher than change type as you can guess, but here I want to draw your attention in some points

• Safety alert SB, in this type of service bulletin SB, you will find the “ALERT “phrase at the top of each page, and of course, this type is incorporated with AD issued by FAA or possibly will release an AD to make task compliance and time frame mandatory.
• Significant safety issue SB, in this type of service bulletin SB, you will find “SPECIAL ATTENTION “phrase in the top, also this type of SB usually Boeing recommend each aircraft operator to examine this SB immediately, also may recommend time frame to complete and the FAA possibly will release an AD for this SB type

· Pratt & Whitney:

Thank you “Pratt & Whitney” for making it organized and simple to understand, as you can see in their Canada website.

The following P&WC compliance guidelines apply to service bulletins issued or revised after August 8, 1998.

Also, they make a group for compliance of the service bulletin as you can see in below table:

· GE SB category classification

GE Service Bulletins are issued with different compliance categories and recommendation statements to assist an operation/shop in assessments of the Service Bulletin priority.

Category 1
 
Usual Statement: Do before a subsequent flight or before XX hours, YY cycles, or specific end date or specific interval. 
 
Explanation: Compliance is mandatory and is the result of FAA action - AD, NPRM, or pending AD. This category does require action within a specified time frame and must be complied with on all engines presently in the shop. 
 
Category 2
 
Usual Statement: Do as soon as possible without effect on revenue service or before XX hours, YY cycles, or specific end date or specific interval. 
 
Explanation: Compliance is recommended based on GE technical evaluation and when an aircraft can stay at a line station or maintenance base with the capability to do the procedure. Justification for an hour, cycle, and end date requirements will be based on technical considerations only(safety, risk analysis, etc). This category may cause non-routine operator action and must be complied with on all engines presently in the shop.
 

Category 3
 
Usual Statement: Do at the next shop visit of the engine or module. 
 
Explanation: Compliance is necessary regardless of shop visit reason. Disassembly of engine or module may be required to incorporate bulletin. Incorporation of this SB will enhance engine reliability and reduce the potential for operation disruptions. May cause further disassembly than planned.

Category 4
 
Usual Statement: Do when the area is exposed. 
 
Explanation: Technical evaluation indicates that incorporation of this SB may enhance engine operational reliability or improve time on-wing. Disassembly of a module to piece part may be required to incorporate this bulletin. 
 
Category 5
 
Usual Statement: Do as soon as the affected part is removed from the engine 
 
Explanation: Technical evaluation indicates that the incorporation of this SB is expected to improve (reduce) maintenance costs. This SB should be incorporated when the part is removed from the engine for other reasons. 
 
Category 6
 
Usual Statement: Do when the part is routed for repair 
 
Explanation: Do when the affected part is being routed for repair. Incorporation of this SB should improve maintenance costs in the future.  

Category 7
 
Usual Statement: Do at customer convenience/option 
 
Explanation: An alternate configuration/part is being introduced into production that may have a different appearance or may require unique assembly or maintenance practices. 
 
Category 8
 
Usual Statement: Spare parts information 
 
Explanation: Use for release/introduction of spare parts that are fully interchangeable and are not anticipated reliability or maintenance costs improvements. 
 
Category 9
 
Usual Statement: Information only 
 
Explanation: Issued to announce specific name brand information (approved oils, etc.) or for administrative purposes. 

Frequently asked questions FAQ about SB:

• What is "Alert SB"? Is the operator have to comply with?

Alert service bulletins are issued by the manufacturer when a certain condition exists that may be a safety-related item as a proposal to just a product improvement. Until here the operator has the right to not comply with, but these SB's usually result in the FAA/EASA issuing an AD. The AD will reference the alert service bulletin as a method of compliance with the AD airworthiness directive.

• Do I have to comply with a "mandatory SB" Service Bulletin?

As per EASA site” Through the DOA (Design Organization Approval) oversight process, the Agency promotes that TC/STC holders designate a Service Bulletin (SB) as mandatory only if it is known to them that this SB will also be covered by an AD. In all other cases, the TC/STC holder should use a term like ’highly recommended ‘(or equivalent). However, this is not yet common practice and there are still cases where an SB is termed ’mandatory ‘by the TC/STC holder, although no AD is to be issued. The Agency has no legal tools to prohibit the use of the word ‘mandatory’ by TC/STC holders, but EASA Certification Memorandum CM-21.A-J-001 has been issued to provide advice and guidance on this subject.

The case of an SB for which an AD has been issued, irrespective of whether it is designated by the TC/STC holder as ‘mandatory’, ‘alert’ or ‘highly recommended’, is clear: these are part of the Mandatory Continuing Airworthiness Instructions and must be applied in all cases.

The case of SBs designated as ‘mandatory’, ‘alert’ or ‘highly recommended’ by the TC/STC holder for which no AD has been issued is more complex and the following cases should be considered:

• The TC/STC holder subsequently includes such SB (e.g. repetitive inspection instructions) in the manufacturer maintenance program (Maintenance Review Board Report (MRBR) or Manufacturer Recommended Program) for the aircraft concerned. In this case, the SB under consideration will need to be included in the aircraft maintenance program as defined in Commission Regulation (EU) No 1321/2014, M.A.302(d) and (g) (see also AMC M.A.302(d)) to ensure compliance with instructions for continuing airworthiness issued by the TC/STC holder.
• The TC/STC holder does not include such SB in the manufacturer maintenance program (MRBR or Manufacturer Recommended Program) for the aircraft concerned. In this case, the final decision to apply such SB lies with the owner/operator or contracted CAMO, as M.A.302(g) does not apply.
• The TC/STC holder issues an SB defining a modification, the related embodiment instruction and the relevant scheduled maintenance requirements, where these may or may not be subsequently included in the manufacturer maintenance program (MRBR or Manufacturer Recommended Program) for the aircraft concerned. In case the SB will not be included in the manufacturer maintenance program, the final decision to apply it or not lies with the owner/ operator or contracted CAMO. If the final decision is to apply the SB, then the aircraft maintenance program needs to be updated to include the scheduled maintenance requirements.

Finally, in relation to points 2. and 3. above, for all non-mandatory modifications and/or inspections, including SBs classified by the TC/STC holder as ‘mandatory’, ‘alert’ or ‘highly recommended’ and not covered by a corresponding AD, for all large aircraft, or aircraft used in commercial air transport, an embodiment policy is to be established, as required by M.A.301(7.). That policy should then result in a substantiated (and recorded) operator’s decision for each SB to apply it, or not.”

Finally , if you want add extra information ,question or query we like to hear in the below comment

Definition:

Airworthiness Directives (ADs) are legally enforceable regulations issued by the authority to correct an unsafe condition in a product. product may be an aircraft, engine, propeller, system, units or appliance.

When Authority issue Airworthiness Directives?

ADs usually result from safety issue reported by operators or from the results of aircraft incident/ accident investigations. They are issued either by the national civil aviation authority of the country of aircraft manufacture or of aircraft registration. When ADs are issued by the country of registration they are almost always coordinated with the civil aviation authority of the country of manufacture to ensure that conflicting ADs are not issued.

Who can issue Airworthiness Directives?

Airworthiness Directive AD issued either by:

• the national civil aviation authority of the country of aircraft manufacture, for example EASA (Airbus) and FAA (Boeing).
• Local civil aviation authority of the state of registration.

When ADs are issued by the country of registration they are almost always coordinate with the civil aviation authority of the country of manufacture to ensure that no conflict.

What are the AD types?

The AD types and roles differ from authority to other but here we will take a look on the most popular in commercial and non-commercial aviation field EASA and FAA

EASA classification:

1-      Mandatory Continuing Airworthiness Information MCAI

All mandatory Airworthiness Directives containing emergency airworthiness directives and proposed airworthiness directives.

2-      Sensitive Security Airworthiness Directive (SSAD)

An SSAD is an AD issued or adopted by EASA that mandates certain corrective actions, the content of which includes security sensitive information.

An SSAD record is uploaded in the EASA Safety Publications publishing tool, but only after the end of the SSAD compliance time and without attachments;

3-      Alternative Methods of Compliance to Airworthiness Directives (AMOC to ADs)

An Alternative Method of Compliance (AMOC) is an EASA approved deviation to an AD. It is a different way, other than the one specified in an AD, to address an unsafe condition on products, parts and appliances. An AMOC must provide an acceptable level of safety, equivalent to the level of safety intended for compliance with the original AD.

4-      Non-EU Member State Airworthiness Directives

For products, parts and appliances, for which the Agency only exercises the design responsibilities of the State of Registry, its policy is to endorse automatically the airworthiness directives issued by the State of Design, except if it itself issues a different airworthiness directive or a decision to not adopt the airworthiness directive (Executive Director Decision .

5-      Proposed Airworthiness Directive PAD

In this consultation period of Proposed Airworthiness Directives (PAD), EASA allows users to submit their comments via Safety tool

6-      Emergency Airworthiness Directive EAD

In this type of airworthiness directives often all affected product grounded until corrective action taken to the emergency unsafe condition.

FAA classification:

1-      Notice of Proposed Rulemaking (NPRM), followed by a Final Rule

After discover condition affect safety or result of accident /incident investigation, the proposed solution is published as an NPRM Notice of Proposed Rulemaking, which solicits public comment on the proposed action

2-      Final Rule; Request for Comments

After the comment period closes, the final rule is prepared, considering all substantive comments received, with the rule perhaps being changed as warranted by the comments the preamble to the final rule AD will provide response to the substantive comments or state there were no comments received.

3-      Emergency ADs

In certain cases, the critical nature of an unsafe condition may warrant the immediate adoption of a rule without prior notice and solicitation of comments. This is an exception to the standard process.

Finally , if you want add extra information ,question or query we like to hear in the below comment

1-     FAST magazine -Airbus Customer Services

This free Airbus technical magazine stands for Flight, Airworthiness, Support and Technology.

The articles are written by Airbus engineers, maintenance staff, pilots, instructors, upgrade services, etc. Its objective is to spread over the aviation community, airworthiness authorities, schools and universities, Airbus’ philosophy on technical, research & technology, maintenance and environmental matters, to name a few.

The subjects vary from one edition to another for Airbus’ entire fleet.

You can freely download magazine online or download Airbus application from below links:

• App Store,
• Google Play
• Windows Store.

2-     Safety First- The Airbus Safety Magazine

The Airbus magazine contributing to the enhancement of the safety of aircraft operations by increasing knowledge and communication on safety related topics.

You can freely download magazine online or download Airbus application from below links:

• App Store,
• Google Play

3-     Innovation Quarterly Magazine - Boeing

Innovation Quarterly is a publication by and for the community of technical professionals at Boeing worldwide. Expected release of each edition is February, May, August and November. Comments and letters are invited by email and may be published in subsequent editions. Submissions are subject to editing; no more than 90 words will be published. To submit a letter to the editor, email junu.kim@boeing.com.

4-     Spaceport Magazine - NASA

Spaceport Magazine is a monthly NASA publication that serves Kennedy Space Center employees and the American public. The magazine’s wide topic variety mirrors Kennedy's diverse spaceport operations. From launch processing to center development and employee stories, Spaceport Magazine covers it all.

5-     FAA Safety Briefing

The FAA Safety Policy Voice of Non-commercial General Aviation, FAA Safety Briefing focuses on emergencies in aviation and how we react to them. Feature articles focus on the kind of events that can cause an emergency in flight and how we might prevent and react to them. These topics include: engine failures, the startle effect, smoke and fire, and balloons and power lines

All aircraft should periodically inspect and maintain in airworthy condition to be safe to fly. Some of that maintenance is pre-scheduled. Other types of maintenance are sudden and unscheduled.

Scheduled maintenance:

Aircraft scheduled maintenance is preventative maintenance that is performed at regular intervals. This type of maintenance based on maintenance program regular checks / inspection and these intervals can be determined based on maintenance program planning method, we can categorize scheduled aircraft maintenance to:

1. Line maintenance like:
   • ALC (After Landing Check).
   • PDC (Pre-Departure Check).
   • DC (Daily Check).
   • WC (Weekly Check)
   • Any other check doesn’t need hangar and could be performed as line maintenance.
2. Hangar maintenance like:
   • Heavy Checks.
   • Progressive inspections.
   • Aircraft weighing or any other maintenance activity need hangar to be performed.

Unscheduled Maintenance:

Unlike the scheduled aircraft maintenance, the unscheduled aircraft maintenance occurs anytime a component / unit has malfunctioned or is suspected of malfunctioning, and by definition, this maintenance is unforeseen.

What are reasons for unscheduled maintenance?

The reasons of unscheduled aircraft maintenance are such:

• Pilot or maintenance staff finds a problem during the preflight inspection.
• An in-flight malfunction.
• Problems found during scheduled inspections / check.

How to minimize fleet unscheduled maintenance?

As business wise, aircraft operator aims to decrease the unscheduled maintenance to minimum this can be achieved by:

1. Effective reliability program.
2. Experienced RCB (Reliability control board) take the right decisions and follow up to measure the effectiveness and feedback.
3. Update maintenance program according to operator utilization, special operation past unscheduled maintenance study, occurrence reports study and reliability to minimize fleet unscheduled maintenance.

ADs are issued when the aviation authority -usually manufacturer aviation authority - finds that an unsafe condition exists in a product (aircraft, aircraft engine, propeller, or appliance.)
These AD's notify aircraft owners and operators of potentially unsafe conditions and require special inspections, repairs, or alterations to correct the unsafe condition.

Types of Airworthiness Directives (ADs) according to FAA:

• Notice of Proposed Rulemaking (NPRM):

After an unsafe condition is discovered, a proposed solution is published as an NPRM, which solicits public comment on the proposed action. Request for Comments. In certain cases, the critical nature of an unsafe condition may warrant the immediate adoption of a rule without prior notice and solicitation of comments. This is an exception to the standard process. If time by which the terminating action must be accomplished is too short to allow for public comment (that is, less than 60 days), then a finding of impracticability is justified for the terminating action, and it can be issued as an immediately adopted rule. The immediately adopted rule will be published in the Federal Register with a request for comments. The Final Rule AD may be changed later if substantive comments are received.NPRM link

• Final Rule:

After the comment period closes, the final rule is prepared, taking into account all substantive comments received, with the rule perhaps being changed as warranted by the comments. The preamble to the final rule AD will provide a response to the substantive comments or state there were no comments received.
Final Rule Link

• Emergency Airworthiness Directives EADs:

An Emergency AD is issued when an unsafe condition exists that requires immediate action by an owner/operator. The intent of an Emergency AD is to rapidly correct an urgent safety of flight situation. For more information, see the Emergency AD page.

• Superseded AD:

An AD is considered no longer in effect when it is superseded by a new AD. The superseding AD identifies the AD that is no longer in effect. There are no compliance requirements for an AD that has been superseded.

Types of Airworthiness Directives (ADs) according to EASA:

• Sensitive Security Airworthiness Directive (SSAD):

An SSAD is an AD issued or adopted by EASA that mandates certain corrective actions, the content of which includes security-sensitive information. An SSAD will be disseminated by EASA to those states having affected aircraft on the register. Further distribution of the SSAD to operators of the affected aircraft or other concerned parties remains under the State of Registry responsibility and should be done on a "need to know" basis only. An SSAD record is uploaded in the EASA Safety Publications publishing tool, but only after the end of the SSAD compliance time and without attachments;

• Mandatory Continuing Airworthiness Information MCAI:

The EASA Safety Publications publishing tool (SP Tool) offers a complete list of Airworthiness Directives that have been issued or approved by EASA since 28/09/2003. The tool also contains all Proposed Airworthiness Directives (PAD) and allows users to submit their comments during the consultation period. After 15/09/2008, new Safety Information Bulletins, Foreign State of Design Safety Publications and Foreign State of Design ADs are published within the EASA SP tool. From July 2016, the EASA SP tool also includes Conflict Zone Information Bulletins (CZIB). The subscription service for new publications enables users to define their own filter and to receive notifications for these filtered documents.

Please consult the user guide for information on how to view and filter new publications and on how to subscribe to their automatic notification

From September 2016, the Safety Publications Tool has been changed to include a new taxonomy for Parts and Appliances ADs – click here for details.

Not all the ADs issued by the NAAs prior to 28/09/2003 (start date of the Agency) are included at this time. Any State of Design AD not (yet) located in the EASA SP Tool should be retrieved from the original State of Design National Airworthiness Authority (NAA), likely available on the respective NAA websites.

Service Bulletins (SB)

SB are noticing to aircraft operators from a manufacturer notifying them of product improvement.

Having realized that there were distinct levels of seriousness to a service bulletin, manufacturers started to categorize them as optional, recommended, alert, mandatory, informational, etc. It was left to the manufacturers to classify a service bulletin as they considered best for there was no standard for the terminology. Differentiation between non-mandatory service bulletins is done and decided only by the authority (FAA - EASA).

Types of Service Bulletins:

Mandatory Service Bulletins :

Through the DOA (Design Organization Approval) oversight process, the Agency promotes that TC/STC holders designate a Service Bulletin (SB) as mandatory only if it is known to them that this SB will also be covered by an AD.

• Alert Service Bulletins :

are issued by the manufacturer when a condition exists that the manufacturer feels is a safety-related item as opposed to just a product improvement. These SB's usually result in the FAA /EASA issuing an AD. The AD will reference the alert service bulletin as a method of compliance with the airworthiness directive.

• Service Information Directive (SID) :

Serviced documents that have been determined by the manufacturer to be of value to an owner/operator in the use of a product by enhancing safety, maintenance or economy.

• Service Information Letters (SIL) :

This category includes all information that may be of use to the owner, operator or maintainer of the aircraft.

If a service bulletin is not an alert service bulletin or a bulletin referenced in an AD, it becomes optional and may or may not be incorporated by the operator.

if you want to know more about service bulletin, types, categories ...etc, you can read the post: All About Service Bulletin SB

References :

• EASA.
• FAA.