How to Review Aircraft Logbooks Before Buying a Plane
In an aircraft purchase, the logbooks are the most important paper you will read — more than the paint, the panel, or the interior. They are the airplane's medical history: a continuous, complete set can add tens of thousands of dollars in value, while gaps or missing books can wipe that value out and make the aircraft hard to finance or insure. This guide walks through exactly what to look for before you wire a deposit.
What "the logbooks" actually means
Most aircraft keep separate maintenance records for the airframe, the engine(s), and the propeller(s). Some also have logs for avionics or accessories. You want all of them, and ideally they should be continuous from the day the aircraft left the factory. Before you dig into details, confirm which books exist and which are missing.
1. Check for a continuous, complete history
Lay the books out in chronological order. For a standard-category aircraft, the FAA requires an inspection every 12 calendar months (14 CFR 91.409), so every year should carry an annual inspection sign-off.
- Gaps — years with no entries — are a yellow flag. Where was the airplane, and was it flying? A gap can hide unrecorded damage or deferred maintenance.
- Missing logbooks are the single biggest devaluation in a used aircraft. Buyers, lenders, and insurers all discount heavily for lost history — an "engine log lost" note can knock a serious chunk off the price.
2. Verify Airworthiness Directive (AD) compliance
Airworthiness Directives are mandatory FAA orders that correct an unsafe condition on a specific make and model. If an applicable AD has not been complied with, the aircraft is not airworthy — full stop.
- Look for an AD compliance record listing each applicable AD, the method of compliance, and the date.
- Pay special attention to recurring ADs, which must be repeated at set intervals. An overdue recurring AD is an immediate cost and a grounding item.
- Cross-check the record against the current AD list for the make and model — don't assume the seller's list is complete.
3. Trace damage history and major repairs
Damage history is not automatically disqualifying, but it must be disclosed, properly repaired, and documented — and it affects resale value.
- Look for FAA Form 337 (Major Repair and Alteration), which is filed for major repairs and alterations.
- Watch for entries mentioning "gear-up," "prop strike," "hard landing," "sudden stoppage," or sheet-metal work.
- A prop strike usually mandates an engine teardown inspection — confirm it was actually performed and signed off.
4. Assess the engine's real status
- Find the last major overhaul and compare SMOH (hours Since Major Overhaul) against the manufacturer's TBO (Time Between Overhaul). An engine near or past TBO is a large near-term expense.
- Note the overhaul type — factory new, factory reman, or field overhaul are not equal in value.
- Look for continuity: regular oil changes, compression readings at each annual, and any cylinder work. Long periods of inactivity can be worse for an engine than steady use.
5. Confirm inspections and modifications
- Annual inspections (and 100-hour inspections, if the aircraft was used for hire) should be signed by an appropriately rated mechanic or IA.
- Every modification should be backed by an STC (Supplemental Type Certificate) or a field approval. Undocumented mods are a compliance problem you inherit.
- Check that weight and balance was updated after any equipment change.
Red-flag checklist
- Missing airframe, engine, or propeller logs
- Multi-year gaps with no explanation
- Overdue recurring ADs
- A prop strike or sudden stoppage with no teardown inspection
- Undocumented modifications
- Entries that don't match the aircraft's serial or tail number
- Suspiciously "clean" recent entries with no supporting history
Don't skip the pre-buy inspection
Reviewing the logbooks yourself is step one, not the whole job. Always have an independent A&P/IA who knows the type perform a pre-purchase inspection. The logs tell you what should be true; the inspection confirms what is true.
Make the review faster
Paper logs going back decades are slow to search by hand. Digitizing them turns forty years of handwriting into a searchable record, so you can jump straight to the last annual, every AD, or any prop-strike entry — and even ask an AI assistant questions like "are there any gaps in the maintenance history?" That is exactly what Aero Logbooks is built to do.
Vet a logbook with Aero Logbooks →
This guide is general information, not maintenance or legal advice. Always consult a certificated mechanic and, where appropriate, an aviation attorney for your specific situation.