5 Tips for Aircraft Pre-Purchase Inspections


April 2018

In a previous PIREP, FAA Designated Pilot Examiner, Jason Blair, introduced us to some strategies to consider when looking into an airplane inspection. In this month’s article, he delves deeper into the subject and relates an interesting incident uncovered during an inspection of an airplane.

When a pilot considers purchasing an aircraft, a pre-purchase inspection is a common step in qualifying the aircraft that is being considered. Every aircraft and every seller is a little bit different, but in considering the lessons I have learned through involvement with friends and customers on hundreds of aircraft, five top tips come to mind when conducting a pre-purchase inspection.

Tip #1 - Don’t have the pre-purchase inspection done by a mechanic that currently (or previously) maintains the aircraft.
Yes, people really do this. They take the word of the mechanic who currently works on the plane for the owner. There is no incentive for the current mechanic to point out problems with their current customer’s aircraft. Additionally, if they have signed the aircraft off for any inspections, to point out problems in essence points out things that they missed or purposely didn’t fix.

To get a fresh and unbiased look at an aircraft being considered, find a mechanic that is in no way related to the aircraft. It is even a good idea to travel some distance away so any other mechanics can be kept out of local “turf” wars. A good rule is to go more than 100 miles to get the pre-purchase completed. If the plane isn’t capable of flying that far, take the hint.

Tip #2 - Have the pre-purchase done by a mechanic that REALLY knows the make and model.
Having a mechanic who has never worked on fabric aircraft do a pre-purchase isn’t a great idea when you are looking at buying a 1947 Stinson that is fabric, and the opposite holds true also. Having a mechanic who has only worked on fabric aircraft isn’t going to help when you are looking at a 2016 composite Cirrus. Not every mechanic is familiar with all the Airworthiness Directives (ADs), the systems, or the intricacies of every make and model. Find a mechanic who is familiar with the particular make, if not model, of the aircraft you are considering to get a more thorough inspection that will catch more potential pitfalls.

Tip #3 - Do a thorough check of all applicable ADs.
It’s important to make sure ADs have been complied with. But so is understanding whether the ADs will require additional inspection or maintenance and if so, how often.

Some aircraft have ADs that require frequent trips to a mechanic. This cuts into the time you will be able to fly between trips to the mechanic, and increases the costs that will be associated with flying between annual inspections. Be sure to check ADs not just on the airframe, but also the engine, heaters, propellers, etc. More components than just the airframe can be subject to ADs.

Common recurring ADs that can be applicable on general aviation aircraft include heater inspections, seat track inspections, control linkages, or exhaust inspections to name a few. When a pilot is considering an aircraft and finds that these need to be completed every 100, 50, or even 25 hours of operation, it can be a major factor in determining if the airplane will meet their flying needs.

Tip #4 - Look deeper into the history of the aircraft.
Logbooks are much like a life’s diary for the aircraft. Take the time to look through them and see what raises questions. Even if something isn’t explicitly written in the logbooks, things that were denoted may lead to important questions.

For example, in a recent pre-purchase inspection a friend had conducted, we found a propeller was replaced at less than 300 hours since it had been overhauled. That seemed strange. On a whim, the prospective buyer did an Internet search of the aircraft tail number and found a forum posting that talked about the aircraft having attempted a takeoff with a tow bar attached to the front wheel. Piecing the two things together, it became obvious that the propeller had struck the tow bar, had been replaced, but no engine overhaul had been completed. This was something that the seller had forgotten to mention to the prospective buyer.

Look carefully through the logbooks to find gaps in flying, major component changes, or even accident records. Sometimes the things not said in logbook entries are as telling as those that are.

Tip #5 - Run the aircraft for more than 5 hours.
Aircrafts that sit and don’t fly often tend to have more problems than those that are actively flown. Most will make it through a quick “test flight” around the traffic pattern without showing many problems. But aircraft that are flown for a longer period of time tend to show more things…like oil leaks, fouling plugs, or other problems that will creep into view over a longer period of flight time.

This is especially important when purchasing an aircraft that has been parked for a long time. Seals, gaskets, and other parts tend to dry out, crack, and fail when an aircraft has not been operational for extended periods. A low-time engine may look great on paper, but if it hasn’t been operated for a long time it may not make it to the manufacturer’s recommended Time Before Overhaul (TBO).

I find it is a good idea to test fly the aircraft (or have the current owner fly) the aircraft for something more like 5 hours. Have a mechanic take a look before and after that flights have been completed. This is more likely to show any problems than a ground-run or quick test flight.

There are many more tips that can help improve your pre-purchase efforts, but these are the top five I have found to be good starting points to determining if the plane you are considering purchasing is going to be the one you want end up owning.

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Jason Blair is an active single- and multi-engine instructor and an FAA Designated Pilot Examiner with over 5,000 hours total time and over 3,000 hours instruction given, and has flown over 100 different makes and models of general aviation aircraft. In his role as Examiner, over 1,000 pilot certificates have been issued. He currently works for, and in the past, for multiple aviation associations that promote training and general aviation. He also consults on aviation training and regulatory efforts for the general aviation industry. Jason Blair has published works in many aviation publications, a full listing of which can be found at www.jasonblair.net.

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