How to Check an Aircraft's AD History Before Buying

Every US-registered aircraft is subject to a set of FAA rules called Airworthiness Directives (ADs). These are legally enforceable — they must be complied with for the aircraft to remain legally airworthy. If you buy an aircraft with an unaddressed AD, you inherit the problem, and the fix can run from a few hundred dollars to tens of thousands.

This guide explains what ADs are, why serial-number-level matching matters, how to check them manually, and how to do it faster.

What is an Airworthiness Directive?

An AD is a regulation issued by the FAA when an unsafe condition is found in a type of aircraft, engine, propeller, or appliance. ADs require specific actions — inspections, repairs, part replacements, or operating limitations — and they're mandatory for the affected aircraft.

ADs are published in the Federal Register and codified in 14 CFR Part 39. They apply based on the specific aircraft's make, model, and often serial number.

“Applies to model” vs. “applies to serial number”

This is where most buyers get tripped up.

The FAA's Dynamic Regulatory System (DRS) lets you search ADs by make and model. But the results are just a list of ADs that mention your aircraft — not necessarily the ones that apply to it.

An AD might apply to:

• All aircraft of a model
• Certain serial numbers within a model
• Certain serial numbers only if a specific STC is installed
• Certain serial numbers only if a specific engine or propeller is installed

If you buy based on the DRS list alone, you might miss ADs that apply to your specific serial, waste money complying with ADs that don't apply, or buy an aircraft with an unaddressed AD and end up on the hook for it.

Serial-number-level matching is the only way to know what actually applies.

How to check ADs manually

The FAA's DRS is free but painful to use:

1. Go to drs.faa.gov
2. Search by make and model
3. Click through to each AD
4. Read the “Applicability” section
5. Cross-reference the serial range against your specific aircraft
6. Repeat for every AD in the list

For a typical Cessna 172, you'll look at 20+ ADs. For a Bonanza or Cirrus, more. It's a 30–60 minute manual exercise that requires careful reading and often a phone call to the manufacturer to confirm.

How to check ADs faster

We built nnumbercheck.com/ad-check to automate this. You enter an N-number, and the tool:

1. Looks up the aircraft in the FAA registry
2. Pulls the serial number
3. Matches it against a database of AD serial ranges
4. Shows three buckets: Applies, Does not apply, and Verify

We currently have serial-level data for Cessna 152/172/182, Piper PA-28, Cirrus SR22, and Beech G36. We're adding models monthly.

The tool is free and no-signup required.

What to do with an AD list

Once you have your AD list, three questions to answer for each one:

1. Is it complied with? Check the aircraft's logbooks for a sign-off. If it's not there, assume it's not done.
2. Is it still active? Some ADs are superseded by later ADs. Check the effective date and look for superseding directives.
3. Does it have a terminating action? Some ADs end when a specific modification is made. If the aircraft has the terminating action, the repetitive inspections aren't required.

For the aircraft you're considering, ask the seller for:

• The logbooks (all of them, or a clear explanation if some are missing)
• Any AD compliance summaries the owner or shop has prepared
• A recent annual inspection report

Red flags

• No AD compliance log or summary. A well-maintained aircraft usually has one. Missing it isn't fatal but means you'll need to reconstruct it.
• Logbook gaps. Even a few months unaccounted for can hide AD compliance issues.
• Recent paint or refurb. Can cover up other issues, and some ADs specifically trigger after paint (e.g., ruddervator balance on V-tail Bonanzas).
• “Complied but no documentation.” If the compliance isn't signed off in the logbook, it's as good as not done.
• Unfamiliar STCs. Some ADs apply only if a specific STC is installed. If the aircraft has an STC you're not familiar with, look up its AD interaction.