Checklist

The Complete Pre-Buy Inspection Checklist

A detailed checklist for pre-buy aircraft inspections, covering airframe, engine, systems, and documentation review to ensure you buy a sound aircraft.

List Buy Fly

April 13, 2026

10 min read

The Complete Pre-Buy Inspection Checklist for Used Aircraft

A pilot's guide to what your mechanic should check, what questions to ask, and when to walk away.

The pre-buy inspection is the single most important step in buying a used aircraft. A qualified A&P mechanic performing a thorough pre-buy can save a buyer tens of thousands of dollars in unexpected repairs. This checklist covers every major system and component that should be examined before money changes hands.

A typical pre-buy inspection costs between $1,500 and $3,000. That investment routinely prevents $20,000 or more in surprise maintenance costs after closing.

What to Review Before Scheduling the Inspection

Buyers can and should review aircraft documentation before paying for a mechanic's time. Gaps in paperwork are often the first sign of deeper problems.

Request all maintenance logs - these should be complete from the first day of service
Verify that annual inspections have been completed every year with no gaps
Review all Service Bulletins and Airworthiness Directives (ADs) for the airframe and engine
Confirm every applicable AD has been complied with and properly documented
Check engine time since major overhaul (SMOH or TSMOH) and compare against TBO
Look for repetitive maintenance items that may indicate a recurring problem
Request any damage history reports or insurance claims on file
Verify the aircraft registration is current with the FAA and listed in the seller's name
Confirm all logbook entries have legible signatures and correct dates

Airframe Inspection

The airframe inspection covers the exterior structure, wings, tail, landing gear, and cabin interior. Structural damage and corrosion are the most expensive problems to fix.

Exterior Fuselage

Walk around the entire aircraft and look for dents, crumpling, or waviness in the skin
Inspect the paint for crazing or signs of previous repainting, which can indicate prior damage repair
Check all access panels and their edges for corrosion
Look for loose rivets or any evidence of skin repair patches
Inspect the windscreen and all side windows for cracks, crazing, or delamination
Open and close all doors and windows to verify proper seal and smooth operation

Wings and Flight Surfaces

Walk the full wingspan and inspect for waviness, dents, or damage
Operate the ailerons and flaps through their full range of motion and check for smooth movement with no binding
Inspect wing struts (if applicable) for cracks, corrosion, or deformation
Verify all control surfaces move freely and return to neutral position
On composite aircraft, look for signs of glue separation or delamination
Examine the leading edges for dents, erosion, or evidence of bird strikes
Check fuel tank sight glasses for contamination, discoloration, or leaking

Tail Section

Inspect the stabilator or horizontal stabilizer and elevator for corrosion or damage
Verify that all tail control surfaces move smoothly through full range of motion
Check trim tab operation, security, and condition
Inspect the fuselage skin near the tail for stress cracks or waviness
Look for evidence of a tail strike or prop strike, including repainted areas or repaired skin

Landing Gear

Check all tires for condition, tread depth, wear pattern, and proper inflation
Inspect brake pads for remaining thickness and check for uneven wear
Look for brake fluid leaks at calipers, lines, and fittings
Verify all landing lights are operational
Check gear doors for dents, warping, and proper sealing
For retractable gear aircraft, test a full gear up and gear down cycle and verify all warning lights and indicators function correctly

Interior

Check all seats for condition, security, and proper track attachment
Verify every seatbelt and shoulder harness operates correctly and shows no fraying or damage
Inspect cabin walls and headliner for water stains, discoloration, or damage
Pull back carpeting and check for moisture, mildew, or corrosion underneath
Look for corrosion around door seals and window frames
Open and close all doors to confirm they latch solidly and seal properly

Engine Inspection

The engine inspection is where a qualified A&P mechanic provides the most value. Engine problems are among the most expensive issues in any aircraft purchase.

Visual Engine Inspection

Check the entire engine exterior for oil seepage around gaskets, seals, and case halves
Inspect the magnetos and alternator for physical condition and mounting security
Check fuel injectors or carburetor for leaking, corrosion, or damage
Verify all spark plug wires are properly seated and in good condition
Pull the oil dipstick and confirm actual oil level matches the manufacturer's recommendation
Check the engine-driven vacuum pump for condition, security, and proper output pressure
Inspect the propeller spinner and each blade for nicks, cracks, erosion, or damage

Compression Test

A differential compression test measures the health of each cylinder. It is one of the most important diagnostics in a pre-buy.

Each cylinder should achieve at least 60 to 70 psi on a differential compression test
No single cylinder should read more than 10 psi below the highest reading
All compression readings should be recorded in writing and kept with the inspection report
Low compression in any cylinder may indicate worn rings, scored walls, or valve problems

Borescope Inspection

A borescope allows visual inspection inside each cylinder without disassembly. It can reveal problems that compression testing alone may miss.

Inspect intake and exhaust valve faces for pitting, erosion, or improper seating
Check for excessive carbon buildup on valve seats and piston crowns
Look for cylinder wall scoring, scratches, or glazing
Check for signs of oil burning or valve damage
Inspect each piston crown for cracks, erosion, or impact damage

Oil Analysis

Oil analysis is optional but strongly recommended for any aircraft with meaningful engine time. Metal particle content in the oil can reveal internal engine wear before it becomes visible.

Request the mechanic pull an oil sample during the inspection
Compare results against baseline values for the specific engine model
Elevated iron, aluminum, or chromium levels may indicate accelerated internal wear

Aircraft Systems and Components

Beyond the airframe and engine, every major aircraft system should be tested and inspected during a pre-buy.

Fuel System

Verify fuel strainers are clear with no visible contamination or debris
Inspect all fuel lines for deterioration, cracking, or chafing
Check fuel tank access panels and surrounding skin for corrosion
Listen for fuel pump hum to verify operation
Operate the fuel selector valve through all positions and confirm it clicks solidly into each detent
Check around fuel caps for fuel smell, which can indicate leaking seals

Electrical System

Test battery voltage at rest, which should read 24 volts or higher on a 24-volt system (12+ on a 12-volt system)
Verify alternator output while the engine is running
Power on all avionics and confirm each unit operates correctly
Test every light on the aircraft: navigation, landing, strobe, beacon, and cabin
Verify radio transmit and receive on all installed frequencies
Confirm transponder operation on both Mode A and Mode C (or Mode S if equipped)

Flight Controls

Manually move each control surface through its full range of motion
Listen for unusual noises, grinding, clicking, or binding during control movement
Verify pitch and roll trim operation (and rudder trim if equipped)
Check control columns or yokes for excessive play or looseness
Confirm ailerons, elevator, and rudder respond smoothly and proportionally to control input

Instruments and Avionics

Verify all six primary flight instruments operate correctly: airspeed, attitude, altimeter, turn coordinator, heading indicator, and vertical speed
Check the attitude indicator cage and uncage mechanism
Confirm the airspeed indicator needle moves smoothly through its range
Verify the altimeter setting mechanism adjusts correctly and the instrument reads within 75 feet of field elevation
Check the heading indicator for proper precession rate
Test all installed avionics against the equipment list in the Pilot's Operating Handbook (POH)
For glass cockpit aircraft, verify all display screens, processors, and backup systems function correctly

Environmental Systems

Test cabin heat and ventilation at multiple settings
If an oxygen system is installed, check bottle pressure, flow rate, and mask condition
Verify defroster output reaches the windscreen effectively
Inspect all air filters for contamination, damage, or age

Major Red Flags That Should Stop a Purchase

If a pre-buy inspection reveals any of the following issues, buyers should seriously reconsider the purchase or renegotiate the price significantly.

Significant corrosion on the airframe. Widespread aluminum corrosion is evidence of poor long-term maintenance and storage. Corrosion repair is labor-intensive and expensive.
A cracked engine case. Engine case cracks are usually not economical to repair. Replacement cases and the associated labor often approach the cost of a full engine overhaul.
Undocumented propeller damage. An undisclosed prop strike suggests the seller is hiding maintenance history. A prop strike can cause internal crankshaft and engine damage that is invisible from outside the engine.
Gaps in annual inspections. Any period without a completed annual inspection means the aircraft was legally unairworthy during that time. This is a serious regulatory and safety concern.
Incomplete AD compliance. An aircraft cannot legally fly until all applicable Airworthiness Directives have been complied with. Outstanding ADs represent both a safety risk and an unknown cost.
Play or grinding in flight controls. Excessive play in control cables, bellcranks, or bearings is a safety-of-flight issue that requires immediate repair.
Soft or wet spots in the fuselage skin. These indicate internal corrosion and potential structural compromise that may require extensive repair or panel replacement.
Compression below 50 psi on any cylinder. Readings this low suggest the engine is approaching or past the point where a major overhaul is necessary.
Multiple electrical system failures. Electrical problems are time-consuming and expensive to troubleshoot. Multiple failures suggest systemic wiring or component issues.

What to Do After the Inspection

A pre-buy inspection is only useful if the buyer acts on the findings.

Obtain a complete written inspection report detailing every finding, measurement, and observation
Request cost estimates from the mechanic for all deferred maintenance and recommended repairs
Ask the mechanic directly: "Would you personally fly this aircraft tomorrow?"
Subtract the estimated cost of necessary repairs from your purchase offer
Ask the mechanic to identify any airworthiness concerns that must be corrected before the aircraft can legally fly
If the seller refuses to allow a pre-buy inspection or limits the scope of the inspection, walk away

Summary

A pre-buy inspection is a buyer's best protection against expensive surprises in a used aircraft purchase. The inspection typically costs $1,500 to $3,000 and covers the airframe, engine, avionics, flight controls, fuel system, electrical system, and environmental systems. Every aircraft buyer should hire an A&P mechanic who specializes in the specific aircraft type being purchased. Walking away from a bad deal is always cheaper than fixing problems after the sale closes.

Published by ListBuyFly.com, the nationwide marketplace for buying and selling general aviation aircraft.

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