A well-maintained aircraft is a safe aircraft, and every pilot knows that regular FAA-mandated safety inspections and regular maintenance is a part of keeping an aircraft well maintained. Another essential component of great maintenance is paying attention to the airworthiness directives and service bulletins. These two methods of maintenance advisories can alert pilots to potential maintenance problems before they create an in-flight emergency, but which of these are mandatory and which can you potentially defer?

Airworthiness Directives (AD)

Airworthiness directives are mandatory. These are issued by the FAA and are considered legally enforceable rules under 14 CFR Part 39. Airworthiness directives are issued when the FAA discovers that a product or part on the aircraft is defective or unsafe, and/or when that defect is likely to affect other products or parts of the same design.

Complying with an Airworthiness Directive

Airworthiness directives list the area of the aircraft or part/s that are to be inspected and repaired or replaced. In some instances, more frequent inspections of the affected part or section of the aircraft are required, and maintenance is not required unless a problem is discovered.

Consequences of Noncompliance

Not complying with an airworthiness directive within the time frame specified in the directive means the pilot is in violation of 14 CFR Part 39.7. In other words, an aircraft that is not compliant with an airworthiness directive is not considered airworthy and cannot be flown legally.

Service Bulletins

Service Bulletins may or may not be mandatory. If you are operating under 14 CFR Part 121 or Part 135, which pertain to air carrier and operator certification, or the service bulletin is attached to an airworthiness directive, it may be considered mandatory. If you are not operating under 14 CFR Parts 121 or 135 or the service bulletin is not attached to an airworthiness directive, the maintenance is not required and can be deferred.

It is also important to note that service bulletins are not issued by the FAA. Instead, they are issued by aircraft manufacturers, engine manufacturers and aircraft parts manufacturers when they discover that a product or part of the aircraft may be defective and may hinder the operation of the flight or create an unsafe condition.

Types of Service Bulletins

Aircraft manufacturers typically categorize their service bulletins so that pilots, aircraft owners and aircraft maintenance technicians can quickly determine if immediate action needs to be taken or if the information in the bulletin simply needs to be noted as something to check during the regular 50-hour, 100-hour and annual inspections. The types of service bulletins are typically self-explanatory.

  • Informational
  • Optional
  • Recommended
  • Alert
  • Mandatory

Determining When a Service Bulletin Should Result in Repairs

Since service bulletins aren’t mandated by the FAA unless the aircraft is operating under 14 CFR Parts 121 or 135 or attached to an AD, additional inspections, repairs and replacement parts may not be needed in order to improve the safety of the flight or keep the aircraft airworthy. However, owners and pilots should not attempt to determine if the service bulletin should be obeyed. Instead, it is usually best to have an aircraft maintenance technician read the service bulletin and inspect the aircraft in order to determine if repairs are needed. Additionally, the owner can request a cost/benefit analysis to determine the risks and rewards of performing maintenance in accordance with the service bulletin.

When Service Bulletins Are Mandatory

If a service bulletin must be complied with because the aircraft is operated in accordance with 14 CFR Part 121 or 135, it is the aircraft owner and/or operator’s responsibility to comply. This means that the corrective action required by the airworthiness directive must be completed by a qualified aircraft maintenance technician, like those at Double M Aviation, in order to maintain the aircraft’s airworthiness.

Complying with ADs and Service Bulletins with Help From Double M Aviation

Here at Double M Aviation, our airframe and powerplant maintenance technicians can ensure your aircraft is in compliance with all the applicable airworthiness directives and service bulletins. If you aren’t sure if a service bulletin applies to your aircraft or if it needs to be addressed, our maintenance technicians can check to see if it is attached to an AD, inspect the part, or perform a cost/benefit analysis.

To learn more about our aircraft maintenance services and how we can keep your general aviation aircraft airworthy and safe to fly, give us a call at 863-940-3450.