Evaluating An Aircraft for Purchase

Maintenance records are required for several reasons. Safety is one and their effect on the value of an aircraft is another. Joe Hertzler writes about the impact that records, or lack thereof, can have on the value of an aircraft.


A common shortcut that a buyer will take is to perform an abbreviated inspection based on the fact that a major inspection was just accomplished. We are opposed to that approach and have seen several instances when the shortcut came back to bite the new owner. In all cases, a complete tip-to-tail inspection must be performed on the prospective aircraft. Similarly, in all cases, a detailed engine inspection must be accomplished. Prior to beginning the inspection, the aircraft should be flown and an “at altitude” engine power check performed. Then ground runs including an avionics systems functional check and engine ground power checks must be performed. We recommend that your mechanic participate in both flight and ground runs. Engine runs can tell a good engine mechanic a lot. Any discrepancies found during the aircraft operational checks should be recorded on the work order so that during final runs, complete correction of the discrepancies can be verified.

The physical inspection of the external and internal components of the engine is also a must. The external part will be included in the tip-to-tail inspection; however the internal inspection will mean, at minimum, a borescope inspection of the hot section and gas generator sections of the engine. We encourage the buyer to have the engines disassembled enough for the mechanic to look directly at the hot section components and check for damage. For engines where disassembly is not practical, a borescope may be the only option. The fact is that borescope technology has come a long way and problems are easier to see with the newer scopes. In all cases the inspection must be complete and detailed. Engine components are extremely expensive and if a serious problem exists, it needs to be uncovered as part of the prepurchase.

The Aircraft Maintenance Records Audit

The second element of the prepurchase is the aircraft maintenance records audit. Please do not underestimate the importance of this element. Just as worn parts or hidden damage can come to the surface later in life and cost the buyer significantly, so can undocumented scheduled maintenance and inspections. The value of an aircraft can be dramatically affected by missing records or hidden damage to the aircraft. Sometimes as much as 15 to 20 percent of the value of the aircraft can be lost simply by maintenance documentation problems. When you are dealing with a multimillion dollar aircraft even 1 percent is significant.

The maintenance record audit consists of the following checks at a minimum.

  • Verification of the aircraft/engine/propeller total time in service

  • Verification of all scheduled inspections and maintenance checks specified by the aircraft manufacturer (including the engines, props appliances, and emergency and survival equipment (Ref: Part 91.409 (e))

  • Identification of the chosen maintenance program for the aircraft

  • Comparison — if necessary to the manufacturer’s inspection program

  • Verification of compliance with all applicable airworthiness directives

  • Complete status of compliance with applicable service bulletins

  • Evidence of possible damage history hidden within the records

  • Completeness of all maintenance records including all FAA Form 337’s and required supporting approved data for major alterations and major repairs

  • Compliance with all instructions for continued airworthiness (ICA’s) associated with any major alterations or supplemental type certificates.

These checks are to be accomplished by conducting a complete and thorough examination of the maintenance records. Oftentimes to complete the audit, the technician must first organize the records to facilitate the audit. We often receive records in such disorder that half of the first day is spent organizing the records.

The audit begins by starting with the most recent logbook and the most recent logbook entry and moving backward through the records reading each entry carefully. It is important that the person performing the audit be very familiar with the inspection and maintenance program for the aircraft. This will be very helpful in making the maintenance records audit efficient since there are often several hundred scheduled maintenance or inspection tasks that must be documented in the records.

As the audit process continues and the information is found in the maintenance records, the technician must accumulate the findings in a format that will allow presentation of a summary of the data and the current status (next due) of each scheduled item, airworthiness directive, service bulletin, etc. In addition we also need to find any major alterations and/or major repairs. Major alterations are required to be recorded using FAA Form 337, however, the major repairs may be recorded using a signed copy of the work order if and only if the work was preformed by an FAA certificated repair station (Ref: Part 43 Appendix B (b)) and the repair station meets all of the criteria in Part 43 Appendix B.

We Recommend

  • Article

    A Market Flooded With Used Aircraft

    Do that inspection, know what you are buying

  • Article

    Aircraft Pre-purchase Evaluations

    From the maintenance perspective By Joe Hertzler This in the most beautiful aircraft I have ever seen in my entire life! What a complimenting situation to find yourself in. An...

  • Article

    Logbook Research Part 2

    Logbook Research It's not just an AD search any more. Part 2 of 2 By Joe Hertzler This is the second in a two-part series on the process of evaluating the maintenance records of an...

  • Article

    Mandatory Service Bulletins: Are they really mandatory?

    Are they really mandatory? By Joe Escobar Is a manufacturer's mandatory service bulletin mandatory or not? This topic pops up in hangars regularly and tends to polarize A&P's and IA's...