An Airworthiness Directive is mandatory for every product it applies to, whether issued by the FAA under 14 CFR Part 39, by EASA, or by the state of design. A service bulletin generally is not, unless an AD, an airworthiness limitation or the operator’s program makes it so. The difficult part is applicability: effectivity by serial or line number, configuration, modification status and installed STCs, especially on converted VIP and special-mission aircraft.
What the evaluation covers
- Applicability of each AD to the airframe, engines, APU and appliances, with the reasoning recorded
- Compliance method and any repetitive requirements, captured for your tracking system
- Service bulletins reviewed for their effect on the maintenance program, including those referenced by ADs
- Interactions with installed STCs, such as winglets, VIP interiors and auxiliary fuel systems
- A written evaluation for the aircraft records
For operators under Parts 91, 121, 125 and 135, EASA and other authorities.
Frequently asked questions
Is service bulletin compliance mandatory?
For most operators a service bulletin is advisory unless an AD requires it, it is part of an airworthiness limitation, or the operator’s approved maintenance program incorporates it.
Why does applicability need an engineering review?
Effectivity often depends on line number, modification status or STCs installed after delivery. A directive can apply to one aircraft and not to its sister ship.
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