What is an Airworthiness Directive?
An Airworthiness Directive (AD) is the FAA's mandatory action notice — issued under 14 CFR Part 39 — when an unsafe condition exists in a type-certificated product and the condition is likely to exist in other products of the same type design. ADs are not advisories: they have the force of regulation. Non-compliance grounds the aircraft.
ADs come from the FAA Aircraft Certification Service (typically the regional ACO). They cover airframes, engines, propellers, appliances (avionics, life rafts, oxygen systems), and increasingly software updates for FBW or avionics systems.
AD types: emergency, immediate, and standard
Emergency ADs are issued without notice when the unsafe condition requires immediate action — typically same-day grounding for severity reasons. They're rare but consequential when they arrive. Telegraphic ADs are the modern equivalent for urgent issuance.
Standard ADs follow a Notice of Proposed Rulemaking (NPRM) process with public comment. They're the most common — issued months to a year after the unsafe condition is identified, with compliance windows from 30 days to 5 years depending on severity.
Recurring vs one-time ADs
A one-time AD specifies a single action — replace a part, perform an inspection, install a software update. Compliance is documented once and stays compliant.
Recurring ADs require repeated action at calendar or flight-hour intervals — for example, a fuel-quantity-indication system check every 1000 flight hours, or a corrosion inspection every 12 months. The system tracking your fleet must compute the next-due date from the last compliance + the recurring interval automatically.
Compliance documentation requirements
FAR 91.417 governs maintenance recordkeeping. For ADs specifically, the record must include: AD number, compliance method (revision, paragraph, or alternative method of compliance), date and total time in service at compliance, signature of the certificated mechanic, and reference to the next due date for recurring ADs.
These records must be retained until the work is repeated, superseded, or the aircraft is exported/scrapped. In practice, most operators keep AD compliance records for the life of the aircraft.
What software-supported AD compliance looks like
AD compliance broken across spreadsheets and binders is high-risk. The minimum software bar: a per-aircraft register of every applicable AD with its compliance status (Compliant / Due-Soon / Overdue / Not Applicable / Superseded), recurring intervals computed automatically, and audit-grade signoff records that capture mechanic name, license number, date, and aircraft total time at compliance.
AviationAlley's airworthiness_directives schema (packages/db/src/schema/aircraft-program.ts) supports this: status enum, recurring interval months, last-compliance and next-compliance dates auto-computed, manufacturer documentation URL, and full audit trail on every signoff. The maintenance rollup at /app/maintenance surfaces overdue and due-soon ADs across the fleet on one screen.
Frequently asked questions
Are Service Bulletins (SBs) the same as ADs?
No — SBs are manufacturer-issued recommendations, not regulatory mandates. An AD can incorporate an SB by reference, making the SB mandatory; otherwise an SB is optional. Smart operators treat SBs as serious recommendations because the manufacturer's data is what the FAA used to issue the AD.
What happens if I miss an AD compliance deadline?
The aircraft is no longer airworthy. Until you comply (or get an Alternative Method of Compliance — AMOC — approved), the aircraft cannot fly under FAA jurisdiction. Operating it anyway is a Part 91 violation and grounds for certificate action against the operator and the responsible airworthiness inspector.
How do I know which ADs apply to my aircraft?
The FAA maintains the Regulatory and Guidance Library at drs.faa.gov. ADs are indexed by aircraft make/model/serial number. Operators typically also subscribe to manufacturer AD-tracking services that filter for their specific fleet.
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