The Prebuy Inspection: What It Is and What It Costs

A prebuy inspection is the single most important step in this list, because it is the one point where an independent expert examines the specific airplane you are about to buy — not a class of airplane, this one, with its own logbooks and history.

How a prebuy differs from an annual

An annual inspection confirms the airplane meets the minimum standard to keep flying legally. It is not a purchase evaluation, and a fresh annual is not a substitute for a prebuy — a mechanic signing off an annual is working from a checklist aimed at airworthiness, not resale condition, and has no obligation to flag a marginal cylinder that is still within limits or a repair that is documented but poorly executed. A prebuy is commissioned by you, scoped by you, and reported to you.

Who should do it

The prebuy must be performed by a shop or mechanic you choose — independent of the seller, and ideally with no prior relationship to the airplane. The seller's regular mechanic knows the airplane's history and may have signed off the very work you are trying to evaluate; even an honest mechanic in that position has an incentive, conscious or not, to see their own prior work favorably. An independent set of eyes, ideally experienced with the specific type, is the entire point of the exercise.

What it costs

Prebuy pricing is commonly quoted in the $1,000–$3,000 range for a piston single, though it varies by shop, region, and how much you ask for — a basic prebuy sits closer to the low end, while adding a borescope inspection, oil analysis, and a full logbook and AD review pushes it higher. Retractable-gear and twin-engine aircraft typically cost more to inspect thoroughly than a simple fixed-gear single. Treat any quote as an estimate to confirm with the shop, not a fixed price — ask what is included before you commit.

What a thorough prebuy covers

A good prebuy goes well beyond a walk-around. Expect the shop to check:

• Compression on each cylinder, the standard first read on engine health, along with a look at oil filter and screen contents for metal.
• Corrosion, especially in areas specific to how and where the airplane has been kept — coastal storage and infrequent flying are both corrosion risks.
• Logbooks and AD review, matched to the actual airframe and engine serial numbers, checking for gaps and confirming which airworthiness directives are applicable and whether compliance is documented.
• Type-specific problem areas — the parts of that particular model known to need attention, which a mechanic experienced with the type will already know to check closely.

Turning findings into a decision

A prebuy rarely comes back clean, and it does not need to. Most findings are normal wear that becomes a negotiating point: a price reduction, a seller-funded repair before closing, or an agreed credit at closing. The findings that matter are the ones that change the fundamental economics or safety of the airplane — a cylinder near replacement, an engine close to or past TBO with no reserve reflected in the price, or a repair that was never properly documented. Those are the findings worth walking away from, not the ordinary squawks every airplane accumulates.