FAA Airworthiness Directives: compliance and tracking

An Airworthiness Directive (AD) is a legally enforceable regulation issued by the FAA under 14 CFR Part 39 when an unsafe condition is found to exist in an aircraft, engine, propeller, or appliance, and that condition is likely to exist or develop in other products of the same type design. ADs are the FAA's primary mechanism for addressing safety deficiencies discovered after a product has been certificated and entered service.

ADs are not optional. Unlike service bulletins (SBs) issued by manufacturers, which are recommendations, ADs carry the force of federal regulation. The aircraft owner or operator is responsible for ensuring compliance within the specified timeframe. An aircraft that is not in compliance with all applicable ADs is not airworthy and may not be operated.

The AD system is reactive — it responds to problems found in the field through accident investigation, service difficulty reports, manufacturer discoveries, or reports from operators and mechanics. When the FAA determines that an unsafe condition exists and corrective action is needed, it issues an AD specifying what must be done, when it must be done, and who is affected.

ADs follow a standardized format that includes several key sections. The applicability section specifies exactly which products are affected — typically by manufacturer, model, and serial number range. The unsafe condition section describes the deficiency that prompted the AD. The compliance section defines exactly what must be done and within what timeframe (hours in service, calendar time, cycles, or before further flight).

AD numbering follows the format YYYY-NN-NN (year, sequential number, amendment number). For example, AD 2025-12-05 would be the fifth AD in the twelfth group issued in 2025. Emergency ADs may use an "E" suffix. Superseded ADs are replaced by newer ADs that incorporate or expand the original requirements.

Each AD also includes an alternative methods of compliance (AMOC) provision. If the specified compliance method is impractical for a specific installation, the owner may request an AMOC from the FAA. AMOCs must be approved in writing before being used as an alternative to the stated compliance action. Some ADs reference manufacturer service bulletins as the approved compliance method, which can create confusion — the SB itself is not mandatory, but when referenced by an AD, the actions described in the SB become required.

Standard ADsfollow the full Federal Register rulemaking process. The FAA publishes a Notice of Proposed Rulemaking (NPRM), accepts public comments for a defined period (typically 30-60 days), considers the comments, and then publishes the final rule. This process typically takes 6-18 months. Standard ADs allow reasonable compliance timelines — often "within the next 500 hours time in service" or "within 12 calendar months" — giving owners time to schedule the work.

Emergency ADs bypass the NPRM process entirely. When the FAA determines that an unsafe condition requires immediate corrective action, it issues an Emergency AD that takes effect upon receipt. Emergency ADs typically require compliance before further flight or within a very short timeframe (often 10-50 hours). These are reserved for conditions where continued operation could result in catastrophic failure, structural collapse, or loss of control.

The FAA may also issue Special Airworthiness Information Bulletins (SAIBs), which are informational notices that do not carry the regulatory force of ADs but alert owners and operators to potential safety issues. SAIBs often precede ADs — they signal that the FAA is investigating a condition that may eventually require mandatory action.

The FAA's official source for ADs is the Regulatory and Guidance Library, accessed through the FAA website. The AD search tool allows filtering by product type (aircraft, engine, propeller, appliance), manufacturer, model, and keyword. You can also search by AD number directly if you have a specific reference.

For a specific aircraft, the most reliable method is to search by type certificate data sheet (TCDS) product. For example, if you own a Cessna 172S, you would search for ADs applicable to the Cessna 172 series, the Lycoming IO-360-L2A engine (or whichever engine is installed), and the McCauley propeller model. Each component may have its own set of applicable ADs. Do not forget appliances — ADs can apply to specific magnetos, alternators, fuel system components, or avionics.

Many aircraft owners maintain a spreadsheet or logbook supplement listing all applicable ADs, their compliance status, and the method of compliance. Several aviation maintenance tracking services offer digital AD tracking that cross-references your specific aircraft serial number and installed components against the current AD database. This is especially valuable because new ADs are issued regularly and applicability can change with component replacements.

AD compliance methods fall into several categories: inspection (visual, NDT, or functional check), modification (physical change to the product), replacement (removing and replacing affected components), limitation (operational restrictions such as reduced inspection intervals), or a combination. Many ADs offer a choice — inspect first, and if the condition is found, then repair or replace.

Repetitive ADs require recurring compliance at specified intervals (e.g., "inspect every 100 hours"). These continue indefinitely until a terminating action is performed — typically a modification that permanently addresses the unsafe condition. Terminating actions are highly valuable because they eliminate the ongoing burden and cost of repetitive inspections.

Record-keeping: AD compliance must be recorded in the aircraft maintenance records per 14 CFR 91.417. The entry must include the AD number, revision date, compliance method, date of compliance, and the signature and certificate number of the person performing the work. For repetitive ADs, the next compliance date or hour must be noted. Incomplete AD records can create significant problems during aircraft sales — buyers and their pre-purchase inspectors will verify full AD compliance history.

During every annual inspection (required under 91.409 for non-commercial Part 91 aircraft) and every 100-hour inspection (required for aircraft used for hire), the inspecting mechanic or IA (Inspection Authorization holder) must verify compliance with all applicable ADs. This is explicitly required by 14 CFR Part 43, Appendix D.

The inspector reviews the aircraft's AD compliance list against the current FAA AD database, verifies that all one-time ADs have been completed, confirms that repetitive ADs are within their compliance intervals, and checks for any new ADs issued since the last inspection. If an applicable AD has not been complied with, the aircraft cannot be returned to service until compliance is achieved.

For aircraft owners, maintaining an organized AD compliance record is one of the most important aspects of aircraft ownership. The record should list every AD applicable to the airframe, engine, propeller, and installed appliances, along with the compliance status and supporting logbook entries. This becomes a critical document during annual inspections, pre-buy inspections, and insurance renewals. An aircraft with clean, well-documented AD history commands higher resale value and inspires buyer confidence.