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

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.

References:

1.                                                          Airbus Safety first magazine

FOR TRAINING PURPOSE ONLY

•  YOU USE THE CORRECT LIFTING/LOWERING EQUIPMENT FOR THE CONDITIONS
•  THE PERSONS WHO OPERATE THE LIFTING/LOWERING EQUIPMENT HAVE THE CORRECT TRAINING AND KNOWLEDGE
•  THE NECESSARY SAFETY AREA IS IDENTIFIED
•  THERE ARE NO UNWANTED PERSONS OR EQUIPMENT IN THIS AREA
•  THERE IS NO WORK IN PROGRESS ON THE AIRCRAFT. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT CAN OCCUR.

MAKE SURE THAT THE LOAD ON THE JACKS IS NOT MORE THAN THE MAXIMUM LOAD SPECIFIED IN THIS PROCEDURE.

MAKE SURE THAT THE WEIGHT OF THE AIRCRAFT IS NOT MORE THAN THE MAXIMUM WEIGHT SPECIFIED IN THIS PROCEDURE.

OBEY THE MANUFACTURER'S INSTRUCTIONS WHEN YOU USE THIS/THESE MATERIAL/S. USE PROTECTIVE CLOTHING AND RUBBER GLOVES.

What is agent used inside fire extinguisher in the aviation ?

Halon gas is the aviation fire extinguisher agent leader , used for suppression fire in many aircraft components such as the engines, APU (auxiliary power units) , cargo compartments and you can find it even in the handheld fire extinguisher bottles through the cabin and the flight deck compartments, tell now the aviation industry can not find a replacement for the halon gas because the regulation insist on a very restricted characteristics, all the civil aircraft including Boeing, airbus are using the halon gas for the fire bottles as a suppression agent for fighting the abnormal fire situations , engines may suffer a nacelle fire so the halon gas must be submitted to extinguish such fire, halon gas is good for all types of fire.

Why " Hallon Gas" ?

• Will not damage engine parts (no negative impact on the engine).
• Very dry gas.
• Non corrosive.
• Not conductive.
• Leave no residue.
• So effective in small quantities (reliable and effective ).
• Effective even in high altitudes .
• compatible with wide range of material and equipment include : electronics - fluids - composites - metals

Types & Usage :

• Hallon 1301 used for Engine - APU - cargo compartment - lavatory.
• Hallon 1211 used for cabin - flight deck - accessible cargo compartment -crew rest compartment - handheld fire extinguisher .

References :

FOR TRAINING PURPOSE ONLY