The logbooks are the aircraft's life story
Request scans of the airframe, engine, and propeller logbooks before you travel to view the aircraft. Missing entries, gaps in annual inspections, or handwriting changes mid-logbook are all worth investigating.
Look for the date and organisation that signed the last annual airworthiness review (ARC in EASA territory). Confirm the ARC is still valid. If it expires within three months, factor the renewal cost (€300–800 typically) into your offer.
Verify all Airworthiness Directives (ADs) that apply to the type have been complied with and are signed off in the logbooks. Repeated AD non-compliance is a dealbreaker.
Engine condition is the single biggest variable
Note the engine hours since new (TTSN) and hours since major overhaul (SMOH). Most piston aircraft engines have a manufacturer-recommended TBO of 1,500–2,000 hours. An engine past TBO isn't automatically dangerous, but budget for an overhaul in your near-term costs.
During the physical inspection, look for oil consumption history (ask the seller), blue smoke on startup, any visible leaks around cylinders and the oil filler area, and metal particles in the oil filter. A borescope inspection of each cylinder bore is essential.
A compression test gives a quick read of cylinder health. Values above 72/80 are generally good; below 60/80 means the cylinder needs attention. Low compression on multiple cylinders significantly affects the aircraft's value.
Avionics: what you see isn't always what's legal
Avionics add significant value but also compliance complexity. Confirm that any installed equipment has a valid STC (Supplemental Type Certificate) for that airframe. Unapproved avionics installations are the owner's liability.
Transponder Mode S with extended squitter (ADS-B Out 1090 MHz) has been mandatory in most European airspace since 2020. Verify the transponder is compliant — non-compliant aircraft are limited to uncontrolled airspace.
Check the avionics database subscription status on GPS units. Out-of-date databases mean the unit cannot be used for IFR approaches and may be legally restricted even for VFR.
Airframe: corrosion, repairs, and modifications
Corrosion is the silent killer of metal airframes, particularly in coastal regions or aircraft stored outdoors. Pay attention to wing attachment points, control surface hinges, the engine firewall, and the underside of the fuselage.
Any major repair (damage history) must be logged with a repair authority sign-off. Ask directly: has this aircraft ever been involved in a ground incident, hard landing, or prop strike? Undisclosed prop strikes can cause internal engine damage that doesn't show up until catastrophic failure.
STCs and field approvals for modifications (STOL kits, aileron gap seals, winglets) are generally fine, but each adds paperwork. Make sure every modification has written approval documentation that transfers to you.
Questions to ask the seller
Why are you selling? (The answer reveals a lot.) How long have you owned it? Where is it usually hangared? Who is the CAMO? Has it ever been rejected during an annual inspection? What squawks are open right now? What's the typical fuel burn you see?
Get the answers in writing via email. This creates a record and often prompts more honest responses than a verbal conversation at the aircraft.