The Age Old Question

Are mandatory service bulletins really mandatory?


From the manufacturer’s perspective, mandatory always means important, even critical at times, but the FAA will only mandate compliance and make it into to an airworthiness directive if deemed necessary. So, the manufacturers need a way to make the service bulletin a permanent part of their inspection and maintenance program. A few of them have simply added a blanket statement as a line item in the inspection program for their aircraft that called for compliance with all service information (there are several variations of this). That approach has created more discussion than compliance, I think. Most manufacturers tie warranty coverage to mandatory service bulletins. For a new aircraft that is usually enough incentive for the operator to comply with all mandatory bulletins, but what about the older aircraft?

Making it mandatory
There is a way, however, for a manufacturer to mandate a service bulletin for all affected aircraft. Requirements called out or referred to in the Type Certificate Data Sheet (TCDS) or within the airworthiness limitations section of the aircraft maintenance manual are, without exception, regulatory. If the manufacturer adds the bulletin’s requirements to either that model’s TCDS or to the aircraft airworthiness limitations section of its maintenance manual, they will, in effect, be mandating those requirements. However, getting the requirement into the TCDS or the airworthiness limitations requires FAA approval and is not near as easy for the manufacturer as issuing a service bulletin and labeling it “mandatory.” Service bulletins are not regulatory just because the manufacturer says that they are mandatory. The FAA has provided an explanation in the form of an Advisory Circular and an FAA Order. I took some excerpts from both and have included them below.

From the FAA
Let’s first look at the FAA’s guidance for us — the industry. Advisory Circular 20-77A “Use of Manufacturer’s Maintenance Manuals” was issued in April of 2007 and really sums up what it takes for a service bulletin to be regulatory.

AC 20-77A Paragraph 6: The FAA recognizes that maintenance practices and requirements are not static and may change as information is developed during the service life of an aircraft. Manufacturers may provide a systematic manual revision system to implement changes to their maintenance instructions. Owner and operators should make allowances for such changes. The following is a list of situations when service bulletins (SB) would be regulatory and covers most situations ASIs encounter if: NOTE: For this section only, all references to manufacturer’s service bulletins will encompass all manufacturer’s service information.

  • All or a portion of a SB is incorporated as part of an airworthiness directive
  • The SB is part of the FAA-approved airworthiness limitations section of the manufacturer’s manual or the type certificate
  • SBs are incorporated directly or by reference into some type of FAA-approved inspection program, such as an Approved Aircraft Inspection Program (AAIP) or CAMP
  • SBs are listed as an additional maintenance requirement in the certificate holder’s OpSpecs

So, to be required by regulation, the service bulletin needs to be incorporated into an airworthiness directive (Reference 14 CFR Part 39) as discussed earlier, or part of the aircraft’s airworthiness limitations contained in the manufacturer’s maintenance manual or type certificate data sheet (Ref 14 CFR Part 91.409).

Airworthiness limitations
Airworthiness limitations are not discussed nearly as much as airworthiness directives. A quick explanation is warranted here. When an aircraft manufacturer receives type certification for a particular aircraft model or models they are also required to identify, in cooperation with the FAA, specific items on the aircraft that must be inspected or replaced periodically in order to ensure safety of flight. These items are the airworthiness limitations. In the text of the TCDS you will find reference to where the airworthiness limitations are listed. It is this “airworthiness limitations” listing that cannot be altered without FAA involvement and approval. In most cases the airworthiness limitations section of the maintenance manual is the only portion that is specifically FAA approved, usually ATA Chapter 4 or a separate document from the maintenance manual altogether. The manufacturer must also establish an “acceptable” inspection and maintenance program for the aircraft, usually found in ATA Chapter 5 of the aircraft maintenance manual. It is the portions of the maintenance manual that have not and in most cases do not, receive FAA approval that the manufacturer can make changes to without specific FAA approval.

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