What are Aircraft Service Bulletins?
A Service Bulletin (S.B.) is a notice to an aircraft operator from a manufacturer informing him/her of a product change / improvement. (often driven by a shortfall or defect or proposed enhancement applicable to an airframe, engine or component.) Aircraft service bulletins are typically sent to the aircraft owner by the aircraft or component manufacturer, service bulletins are not automatically sent to maintenance providers.
An alert service bulletin is issued when an unsafe condition shows up that the manufacturer believes to be a safety related as opposed to a mere improvement of a product.
Aircraft Maintenance Service Bulletins and other technical instructions are issued in several forms, from Service Letters through Service Bulletins to the highest level which is Alert Service Bulletins.
From a due diligence point of view Alert Service Bulletins should be incorporated in accordance with the embodiment instructions.
Who Issues Service Bulletins?
Aircraft Maintenance Service bulletins are issued by the Type Certificate Holder TCH or Original Equipment Manufacturer OEM. Providing guidance to perform an inspection, replace a component or embody a modification. Regardless of how the SB is identified by the issuing company, Service Bulletins are not mandatory, unless they are supported by an Airworthiness Directive AD.
So from a regulatory point of view the SB may not be required. However this is only one part of the story. SB’s may also be driven by Lease Obligations or by Organisational decisions.
Whilst the intention of the SB provider is to raise the standard of safety, the operator may view the cost of the bulletin as not effective for the particular aircraft, engine or component.
For the Operator to automatically comply with service bulletins may result in increased maintenance costs. For this reason it is normal for the Operator to implement a Service Bulletin Analysis process.
Even Free of Charge Service Bulletins may not be free.!
A survey of Service Bulletin true costs showed that the actual cost of embodiment was between 7 to 13 times the basic cost of the Service Bulletin. Therefore it makes sound financial sense to review SB’s not just for Safety Benefits, but for economic benefits and to make a balanced decision to embody.
A template may be used for this purpose which will consider all the relevant criteria which is applicable including the remaining length of the lease, the various obligations, as well as benefits to both safety & reliability. A cost benefit analysis will allow the operator to compare the cost of embodying the aircraft maintenance service bulletin (compliance) in the light of the perceived benefits.
With this information the appropriate decision should become more obvious.
Do I have to comply with a ‘mandatory’ Service Bulletin?
The official EASA position regarding ‘required’ application of SB instructions is as follows:
Through the DOA (Design Organisation 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 programme (Maintenance Review Board Report (MRBR) or Manufacturer Recommended Programme) for the aircraft concerned.
In this case, the SB under consideration will need to be included in the aircraft maintenance programme 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 programme (MRBR or Manufacturer Recommended Programme) 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 programme (MRBR or Manufacturer Recommended Programme) for the aircraft concerned.
In case the SB will not be included in the manufacturer maintenance programme, 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 programme 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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