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:
In this section the manufacturer discus which aircraft, component, serial numbers or part numbers which will apply this SB on.
- Concurrent requirements
Discuss the reason of issuance, and the importance level of the SB also what the operator gain from complying with this SB
General description of what to do to execute the service bulletin
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
This section discusses the approval level of the SB
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.
4) Production Revision Record.
b- Product Safety Type:
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
The following P&WC compliance guidelines apply to service bulletins issued or revised after August 8, 1998.
Implementation Timing Recommendation
P&WC recommends doing this service bulletin before the next flight.
P&WC recommends doing this service bulletin in the first time the aircraft is at a line or maintenance base that can do the procedures.
P&WC recommends doing this service bulletin within ____ hours or ____cycles.
The first time the engine or module is at a maintenance base that can do the procedures, regardless of the scheduled maintenance action or reason for engine removal.
P&WC recommends doing this service bulletin when the engine is disassembled and access is available to the necessary subassembly (i.e. module, accessories, components, or build groups). Do all spare subassemblies.
When the subassembly (i.e. module, accessories, components, or build groups) is disassembled and access is available to the necessary part. Do all spare subassemblies.
You can do this service bulletin when the supply of superseded parts is fully used.
This service bulletin is optional and can be done at the discretion of the operator.
Spare Parts Information.
This is the old Omnibus category of Service Bulletin and is no longer in use except for the PW1000 program. This paragraph is being kept for historical purposes only.
This Service Bulletin is issued to document the modifications done on all engines, after engine certification but before aircraft entry into service. The result is that no Pre-SBXXXXX configuration will appear in the technical publications or the modification accomplished prior to aircraft entry into service.
This Service Bulletin is issued to document the modifications done on all engines, after engine certification but before aircraft entry into service. The result is that no Pre-SBXXXXX configuration will appear in the technical publications for the modification accomplished prior to aircraft entry into service.
Operators who participate should include this Service Bulletin at the next maintenance or overhaul of the engine. .
Also, they make a group for compliance of the service bulletin as you can see in below table:
For conditions which could result in an in-flight shutdown, significant loss of power/thrust or any other similar situation affecting flight safety.
Recommended - Urgent. P&WC recommends (Alert SBs) accomplishment prior to next flight. An Airworthiness Directive has been requested.
Recommended - Most desirable. To be accomplished during next visit to a facility where specified maintenance action(s)/modification(s) can be accomplished.
Currently not used.
Recommend - Highly desirable. To be accomplished prior to part life expiry or within _???_ hours (or _???_ cycles).
Recommend - Highly desirable. P&WC recommends accomplishment at first shop visit of module/engine/power section/RGB/accessory regardless of extent of disassembly.
For conditions which affect engine life (PERs) and operating costs:
Recommended - Desirable. P&WC recommends accomplishment when disassembly of engine/power section/RGB/accessory is sufficient to afford access to the affected module/subassembly.
Recommended - Desirable. P&WC recommends accomplishment when disassembly of engine/power section/RGB/accessory is sufficient to afford access to the affected part.
Recommended - Incorporation applicable to attrition of prior configuration parts when the supply of such items is depleted.
Optional - At the discretion of an operator. P&WC recommends accomplishment based on the operator's experience with prior configuration parts.
Informational - For record purposes and/or to provide useful technical information or to support engine operation/maintenance/logistics.
· 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.”
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