Aviation Business and Law
Airworthiness Directives and Service Bulletins
by Robert B. Schultz Attorney at Law

JANUARY 2001

In a previous article (August 2000), I discussed the Federal Aviation Administration's two-part test for airworthiness-that is, an aircraft is considered airworthy if it conforms to its type specification and is safe to fly. Airworthiness directives and service bulletins directly relate to the airworthiness of an aircraft.

An airworthiness directive (AD) is a Federal Aviation Regulation (FAR 39.11) that directs aircraft owners and operators to perform inspections or repairs on, or limits operation of a particular airframe, engine, propeller or appliance. An appliance is anything used in operating or controlling an aircraft in flight that is installed or attached to the aircraft, but is not part of an airframe, engine or propeller. An altimeter, for example, is an appliance.

The FAA promulgates ADs, like other regulations, after notice to the aviation community and a suitable period for comment. This is called a Notice of Proposed Rule Making (NPRM). In an emergency, the FAA may adopt an AD without prior notice. Regulations, just like statutes, are laws, and like any regulations, ADs have the force and effect of law. Failure to comply with an AD can result in an enforcement action against an owner, operator or mechanic.

FAR 91.7 provides that "no person may operate a civil aircraft unless it is in an airworthy condition." Moreover, FAR 91.403(a) fixes responsibility for compliance with all applicable ADs on the aircraft owner or operator. Thus, any aircraft that does not comply with all applicable ADs is not airworthy and any owner or operator who fails to comply with all applicable ADs is in violation of the FARs.

Manufacturers, on the other hand, issue service bulletins. Even though many are designated as mandatory, unlike ADs, they do not have the force and effect of law. Manufactures have complete discretion to issue service bulletins but their primary motivation is to correct known safety problems before they result in accidents. Indeed, there is little or no downside to the issuance of a service bulletin since, unlike automobile manufacturers, aircraft manufacturers are not required to recall their products or pay the cost of prescribed fixes. Paying for ADs and service bulletins is one of the privileges of aircraft ownership.

Manufacturers cannot issue ADs. While they can recommend them to the FAA, and often do, the FAA sometimes disagrees with the necessity of issuing an AD. The FAA will often disagree with an AD proposed by the manufacturer based on cost. That is, every AD must pass the same regulatory scrutiny required of all regulations including a cost benefit analysis. Accordingly, the FAA will not issue an AD unless the benefits exceed the cost to aircraft owners.

As an aircraft owner or operator, you know you must comply with all applicable ADs. But just because service bulletins are not regulatory, you should not assume they are optional. Recall the second part of the airworthiness test - "safe to fly." If the FAA determines that your aircraft is not safe to fly because it does not comply with a service bulletin, it may be just as unairworthy as if it does not comply with an AD. I am not aware of any such case where an aircraft was found to be unairworthy but it is quite possible. In addition, FAR 43.13(a) requires that aircraft mechanics "use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or Instructions for Continued Airworthiness prepared by its manufacturer." Since the manufacturer's instructions include its service bulletins, a mechanic may be in violation of the FARs for failure to comply with a service bulletin.

Regardless of what the manufacturer says in its flight manual or service bulletins, ADs always take precedent. After the loss of a tail rotor blade was found to have caused the crash of a Tomcat MK5B helicopter in 1981, an enforcement action was brought against the inspector who did the last annual inspection. The MK5B looks like the Bell Model 47 helicopter but has its own type certificate. The manufacturer of the MK5B advertised that its tail rotor blades had a 2,500-hour life. Nonetheless, the FAA argued and the judge agreed that an AD applicable to the Model 47 and all helicopters equipped with the same type tail rotor blades, applied to the MK5B as well. The blades on the accident helicopter were found to have over 1,000 hours while the AD required their replacement at 600 hours. The inspector got off easy with a 30-day suspension.

Robert B. Schultz practices law in Denver and specializes in aviation law. He can be reached at [email protected] and welcomes your comments and questions.