Airworthiness Directives — commonly called ADs — are the FAA's primary tool for mandating corrective action on known unsafe conditions in certificated aircraft, engines, propellers, and appliances. When the FAA discovers a safety defect that could endanger the public, it issues an AD under the authority of 14 CFR Part 39. Unlike service bulletins or manufacturers' recommended maintenance, an AD carries the full force of federal law: an aircraft that does not comply with all applicable ADs is not airworthy, period. For the Aviation Maintenance Technician (AMT), understanding how to record AD compliance correctly is just as important as performing the work itself — an undocumented AD accomplishment is, in a legal sense, an uncompleted one.
This article walks through the regulatory basis for AD compliance recording, the specific data elements that every AD entry must contain, recurring-versus-one-time AD tracking, and the common pitfalls that show up on the AMT General knowledge test and in FAA inspections.
The Regulatory Foundation
The requirement to comply with ADs is stated in 14 CFR 39.7: the owner or operator of a product to which an AD applies must comply with the requirements of that AD. Maintenance recording requirements flow from 14 CFR 43.9 for routine maintenance entries and 14 CFR 43.11 for return-to-service entries after inspections. Additionally, 14 CFR 91.417 dictates what records an owner or operator must keep and for how long. Read together, these regulations create a clear chain: the AD compels the action, 14 CFR 43.9 governs how the accomplishment is recorded in the maintenance record, and 14 CFR 91.417 governs how long that record must be kept.
ADs are also published as amendments to Part 39 in the Code of Federal Regulations and in the Federal Register. Each AD is assigned a unique identifier in the format YY-NN-NN — the year of issuance, the biweekly period of that year in which the AD was issued, and the sequential number of the AD within that biweekly period. For example, an AD numbered 2023-14-05 was issued in 2023, during the fourteenth biweekly period of that year, and is the fifth AD assigned within that period. This identifier must appear verbatim in every maintenance record entry documenting compliance.
What Every AD Compliance Entry Must Contain
Under 14 CFR 43.9, any maintenance record entry — including one for AD compliance — must include all of the following elements:
- Description of the work performed: A clear, specific description of exactly what was done. Simply writing "AD complied with" is insufficient. The entry should describe the actual task: for example, "Inspected wing spar lower cap per AD 2022-08-12, paragraph (c)(1). No cracks found."
- Date the work was completed: The calendar date on which the maintenance was finished and the aircraft was approved for return to service.
- Aircraft total time in service: The airframe total time (in hours) at the time of the work. For recurring ADs, this provides the baseline from which the next compliance interval is calculated.
- Identity of the person performing the work: The name, certificate type, and certificate number of the certificated person who performed or supervised the work.
- Signature and certificate number of the approving person: The signature and certificate number of the certificated mechanic, repairman, or other authorized person returning the aircraft to service.
For AD compliance specifically, best practice — and often a specific AD requirement — is to also record the method of compliance chosen when the AD offers alternatives, and any parts replaced including part numbers and serial numbers. Many ADs mandate that certain data (measured values, findings, or part traceability information) be entered in the aircraft records. Always read the AD's own recording requirements, because some ADs include provisions that go beyond the baseline 14 CFR 43.9 requirements.
One-Time versus Recurring ADs
ADs fall into two broad compliance categories, and your record-keeping approach differs for each.
One-Time (Terminating) ADs
A one-time AD requires a single corrective action — such as replacing a component, modifying a structure, or performing an inspection with a specific pass/fail outcome — that permanently eliminates the unsafe condition. Once accomplished and recorded, no further tracking is required for that AD. The entry in the airframe, engine, or propeller logbook serves as permanent proof of compliance. Keeping this record is critical because the aircraft may change hands; the new owner must be able to verify that the one-time AD was accomplished.
Recurring ADs
Recurring ADs require repetitive action at defined intervals — for example, "inspect every 100 hours" or "inspect every 12 calendar months, whichever comes first." For these ADs, proper record-keeping is essential not just as historical documentation but as an active airworthiness tracking tool. Each time the recurring task is accomplished, a new entry is made with the date and aircraft total time. The next due compliance time or date should either be noted in the record itself or tracked in a separate AD compliance log or status document. Many aircraft operators maintain a dedicated AD compliance status sheet that lists every applicable AD, the method of compliance, the last accomplishment date and time, and the next due date or time. While such a status sheet is not explicitly required by regulation for Part 91 operators, it is an industry best practice and is required for certain air carrier and commercial operations.
When computing the next due date for a recurring AD, count from the date or time of the last accomplishment, not from the date the AD was issued. If the AD says "every 100 hours," and the inspection was completed at 1,350 hours total time, the next inspection is due at 1,450 hours total time. Missing a recurring AD interval renders the aircraft unairworthy immediately, regardless of how well the aircraft seems to be performing.
Where Entries Are Made
AD compliance entries are made in the permanent maintenance records of the affected product. For the airframe, this is the airframe logbook or an equivalent record acceptable under 14 CFR 91.417. For an engine or propeller AD, the entry goes in the engine or propeller logbook. If an AD applies to an appliance (such as an avionics unit or a landing gear actuator), the entry may be made in the airframe record with a clear reference to the affected appliance, or in a separate appliance record if one is maintained. The key principle is that the record must follow the affected product — if an engine is removed and installed on a different airframe, its AD compliance history travels with it.
Record Retention Requirements
Under 14 CFR 91.417(b), the owner or operator must retain records of maintenance, preventive maintenance, alterations, and required inspections for different periods depending on their nature. Specifically, records of the total time in service of the airframe, each engine, each propeller, and each appliance must be retained and transferred with the aircraft when it is sold. Records of the current inspection status and AD compliance status must also be retained. In practical terms, AD compliance entries should be treated as permanent records — they should never be discarded, even when logbooks are full and a new logbook is started. When a new logbook is begun, a summary statement transferring the previous record (including all AD compliance history) must be included.
Key Numbers and Rules
- 14 CFR 39.7 — establishes the legal obligation to comply with ADs.
- 14 CFR 43.9 — sets the minimum data elements for any maintenance record entry.
- 14 CFR 91.417 — governs owner/operator record retention responsibilities.
- AD identifier format: YY-NN-NN — the year, the biweekly period of issuance, and the sequential number within that period; it must be cited verbatim in the logbook entry.
- Recurring AD intervals are counted from the last accomplishment date or time, not from the AD's issuance date.
- An aircraft that is out of compliance with any applicable AD is not airworthy and may not be operated under 14 CFR 39.7.
- Records must accompany the product when transferred — they belong to the aircraft (or engine, propeller, appliance), not the operator.
Common Test Traps
- "AD complied with" is not enough. The test frequently presents an entry that simply states the AD number was complied with. This is insufficient under 14 CFR 43.9 — the description must identify the specific work performed.
- Confusing recurring interval start points. The next due time is calculated from the last accomplishment, not from when the AD was issued or the aircraft was purchased. A test question may present a scenario designed to make you count from the wrong starting point.
- Forgetting total time in service. Many students remember the date but omit the aircraft total time. Both are required, and for recurring ADs the total time is what drives the next compliance deadline.
- One-time AD record permanence. Some test takers assume that once a one-time AD is done, the record can eventually be discarded. In fact, that entry is permanent — it must follow the product for its entire service life.
- AD vs. service bulletin. ADs are mandatory under federal law. Service bulletins are manufacturer recommendations and are not legally required unless an AD specifically incorporates a service bulletin by reference. Treating a service bulletin as optional AD compliance (or vice versa) is a common conceptual error on the knowledge test.