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Aircraft Maintenance: Managing airworthiness directives

Chances are, you’ve heard about the recent airworthiness directive (AD) affecting approximately 2,000 Continental Aerospace Technologies engines and crankshafts.

The recent Continental airworthiness directive involves counterweight snap rings that may not be fully seated in their grooves. Photo courtesy of Ryan Dickerson.

According to the associated Mandatory Service Bulletin (MSB23-01A), Continental discovered a potential assembly error whereby one or more counterweight retaining rings were not properly seated in the crankshaft counterweight groove. This condition could allow the counterweight to depart from the crankshaft during engine operation, resulting in catastrophic engine damage.

To the company’s credit, Continental took action rapidly after the situation was discovered, has been very forthright with its communications, and is offering generous warranty terms for the work required to comply with the AD. The company even shipped out critical tools required to do the work within days of the AD publication. Although this AD is a significant inconvenience to affected owners, I am not aware of any injuries associated with the issue, and the cost of compliance is covered by Continental.

Unfortunately, this is not the typical case with ADs. Most ADs in general aviation result in the owner bearing the burden of compliance, which can be extraordinarily expensive. As an owner, you cannot control the existence of ADs that apply to your aircraft. However, there are things that you can do to mitigate the impact and cost of an AD when it comes your way. It all starts with awareness.


With the exception of emergency ADs, the process for creating an AD is a fairly lengthy one that frequently begins with a service bulletin. While SBs are optional for Part 91 operators, they can give you advance warning of issues that may evolve into ADs. Information is power, because you can use it to get ahead of the curve by inspecting or addressing issues on your timetable, rather than one that is mandated by the FAA. Type clubs are a great resource in this matter, as they routinely advocate on behalf of owners with the FAA and are often on the front lines during the AD creation process. If you stay “in the know” regarding what may be coming down the road, you can look for efficient ways to address problems.


Scheduling is one of the best ways you can help yourself manage the cost of AD compliance. When an AD comes out, there is usually a mad dash for the maintenance resources to meet the AD requirements. At the SB stage, there may still be time to schedule inspections or procure parts before schedules get booked up and shortages affect parts availability. Additionally, time gives you the opportunity to get together with other owners to schedule joint maintenance or purchase parts in bulk. This has been especially true of the Piper Aircraft wing spar AD, which requires special equipment to do eddy current inspection of the spar bolt holes. Getting a technician with the required equipment out to inspect four aircraft on the same day is much more cost-effective than trying to book an inspection for a single aircraft.


FAA Advisory Circular AC 39-7D addresses the documentation for airworthiness directives, including the following:

Required Entries into Records. The person accomplishing the AD is required by § 43.9 to record AD compliance. The entry must include those items specified in § 43.9(a)(1) through (a)(4). The owner or operator is required by § 91.405 to ensure that maintenance personnel make appropriate entries and, by § 91.417, to maintain those records. Owners and operators should note that there is a difference between the records required to be kept by the owner under § 91.417 and those that § 43.9 requires maintenance personnel to make. In either case, the owner or operator is responsible for maintaining proper records.

Continental has provided tools such as this one to aid in compliance with the airworthiness directive. Photo courtesy of Jeff Simon.

This single section of the guidance places the bottom-line responsibility for maintaining records for AD compliance on the owner or operator of the aircraft. If you do not have a succinct and easy-to-read log demonstrating compliance with all ADs on your aircraft, you are doing yourself a disservice that may cost you during your next annual inspection or other maintenance event.

That said, the most important thing you can do to aid yourself in compliance with future ADs is to ensure that your maintenance documentation and logbooks include details that are often overlooked in normal maintenance practices. Specifically, any time that a part is replaced or repaired, the part number, serial number, and work order information should be noted. Personally, I keep a spreadsheet with the installation date, hours, part number, and serial number of every component in the aircraft that I lay my hands on. It’s an ever-growing list. Each time that I work on the aircraft, I’m thinking, “Is this a part that I’ve documented?”

Photos can be powerful tools as well. Any time that the aircraft or engine is opened up for maintenance, take the opportunity to photograph as much as possible, including data plates. Not only will this help you evaluate the impact of potential ADs by using photographic evidence, it can help estimate the cost of a job if you can show your mechanic exactly what’s inside that wing, tail cone, panel, engine compartment, etc.

That’s not a light at the end of the tunnel…it’s a train

Considering the massive supply chain and labor shortages that the industry has faced over the past three years, I suspect we are only beginning to see the fallout in terms of ADs. Even with the extraordinary controls and documentation required for FAA-certified products, it seems inevitable that there will be quality escapes, training issues, counterfeit parts, and other issues. Time will tell, but I believe that now is the time to get ahead of the curve and be prepared.

I’ve spent time at many aviation manufacturers, and I know that they do everything in their power to maintain 100 percent quality in their products. They have my sympathy for fighting that battle now, at a time when turnover rates in suppliers and staff are at unimaginable levels. So, in spite of the crisis facing all those engine owners, I’m grateful that Continental has stepped up to the plate with its warranty coverage and the immediate delivery of the tools to do the job. All of us—owners and manufacturers—are ultimately in this together. The more that we applaud the ones who “do the right thing,” the more likely other companies will do the same in the future. Until next time, I hope you and your families remain safe and healthy, and I wish you blue skies.

Jeff Simon
Jeff Simon
Jeff Simon is an A&P mechanic, IA, pilot, and aircraft owner. He has spent the last 22 years promoting owner-assisted aircraft maintenance and created the first inspection tool for geared alternator couplings available at Jeff is also the creator of SocialFlight, the free mobile app and website that maps more than 20,000 aviation events, hundred-dollar hamburger destinations, and also offers educational aviation videos. Free apps are available for iOS and Android devices, and users can also visit
Topics: Aircraft Maintenance, Airworthiness
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