Pre-Purchase Inspection: All It Should Be

The most important rule in the sales game is “you make your money when you buy something, not when you sell it”. When it comes to buying an airplane it’s about saving money in the long run, and that happens to be a big number in the airplane happiness formula.

As outlined in my previous article, once a thorough search has identified a strong candidate airplane, it’s time to commit to a thorough pre-purchase inspection. In this article is a list of observations and guidelines to follow when arranging for and having this done.

  1. Have the inspection done at a neutral facility by a trusted inspector who is interested in protecting you.
  2. This may sound crazy, but the first thing I would check during a pre-purchase inspection is verification that the data plate and logbooks actually belong to the airplane. Considering the age of the fleet, and the many reasons a less than honest person can benefit from changing the identity of a damaged or stolen airplane, these things happen. At Air Mod we have seen this issue rear its ugly head three times in the past 15 years.
  3. Have copies of the logbooks sent to the inspecting agency in advance. Be suspicious of missing logbooks, sketchy entries or unusual periods of idle time when the aircraft was not flown. This can be an attempt to cover up damage history.
  4. Establish a clear understanding with the seller regarding your expectations, letting them know what constitutes a deal breaker. Be realistic; you are not buying a new airplane. If a non-deal-breaking item is found, be fair and objective in negotiating the cost of fixing it. Don’t be a nitpicker. Choose your battles as to what issues you may want to negotiate.
  5. Confirm that the equipment list conforms to what is actually installed in the airplane. Most importantly, verify that the installed equipment is approved for the candidate airplane and the proper paperwork is in the aircraft’s records verifying approval for installation in that exact make and model of aircraft. It’s also very important to inspect the quality of the workmanship and the components used in the installation.
    The process of acquiring paperwork after the fact for previously installed but undocumented equipment can be expensive and possibly impossible. I like to get a copy of the original equipment list available from the manufacturer and compare it to what is currently installed in the airplane. Any changes are checked out to ensure that required documentation is in either the aircraft or engine logbooks.
  6. Don’t buy a corrosion bucket. Your money is in the airframe. Almost all 30-plus year old airframes, most of which were not zinc chromated when they were manufactured, will have some corrosion. But it can be remediated and controlled with modern technology and proper intervention techniques. I will cover this topic in more detail in future articles as we go through the step by step process of total interior renovation. I feel it is important to point out that in Cessna airframes we tend to find the most cabin corrosion hidden behind the headliner. (photo 1) One can inspect these places by carefully removing the upper trim components and/or opening zippers to gain enough access to inspect the upper cabin, paying close attention to all the spar carry through and attachment components. The rest of the airframe (wings, aft fuselage, tail assembly, etc) is easily inspected by removing inspection panels and fairings.
    Photo 1
  7. Identifying undocumented damage can require a more careful eye. A savvy, experienced technician will know where and how to spot repaired damage. Overset rivets, or driven rivets replaced with blind rivets such as cherry max, are cause for some investigation. Shiny or zinc chromated new components in older airframes are just some of the clues that can reveal a secret. Be curious about a 40-year-old retractable gear airplane; many have had a gear up incident somewhere in the past.
  8. Don’t overlook an evaluation of avionics equipment. Having a knowledgeable technician ground check radios and autopilot is a very good investment. They can confirm that all equipment is approved for installation in the specific make and model of aircraft, and that all components are approved to be working together. They can also verify that the installation was done to a quality standard (unlike in the accompanying picture). (photo 2)
    Photo 2
  9. Be very careful to inspect any modifications that were installed after the aircraft was built. (photo 3) Again, look closely to assess the quality of workmanship and verify that approvals and appropriate paperwork are included in the logbooks.
    Photo 3
  10. One sometimes-overlooked check is to rule out the presence of hail damage. The best way to check for this is to turn off the lights in a closed hangar and put a bright single light source as close to the skin as possible; look for any waviness in the skin surface that will be visible in the very low angle of the light. It is surprisingly difficult to see slight unevenness in a metal surface in bright overhead light. Skilled use of body fillers can 11  Let’s talk engines. Not all engines are created equal. Low horsepower Lycoming 4-cylinder engines of 180hp or less are about as bulletproof as they come. These engines can be evaluated with the usual maintenance record check, compression test, borescope cylinder inspection and an oil filter inspection. High horsepower equals high heat, and high heat equals more stress on cylinders, rings and valves. Add turbo charging and there are more items to check out. These complex engines require careful and knowledgeable management and inspection. I personally believe the most predictable and cost effective plan is to buy a high horsepower airplane with a run out engine and start your relationship with your airplane with a fresh quality overhaul.

It’s important here to point out that not all overhauls are alike. By FAA definition, an engine can be considered overhauled if it has been disassembled, cleaned, inspected and all the critical components are precision measured, ensuring that they meet MINIMUM tolerance. That means that worn but still serviceable parts can be put back in an engine that can then be logged as overhauled and legally signed off for return to airworthy service. If one critical component experiences as little as one thousandth of an inch of wear, the engine is no longer airworthy. So hours since overhaul can have a significant and precarious meaning.

The most predictable way to make sure an overhauled engine makes it to TBO (time between overhaul) is to require that it be overhauled to new limits. That means that all the parts begin their new life fitting exactly to new engine specifications and have a margin for wear that will help to ensure performance longevity and, most importantly, safety all the way to TBO.

Two more engine issues that are important to consider are how active the engine has been and how many years it’s been since it was last overhauled. Be concerned about an engine that was overhauled 20 years ago or has been inactive for an extended period of time. An inactive engine tends to develop corrosion and arthritic components, decreasing the likelihood that the engine and supporting components will make it to TBO. These conditions will often lead to increased maintenance issues along the way.

Writing this article reminded me of a wise older gentleman (fortunately it seems like every airport has one) who said something years ago that I think was probably true at the time but seemed a little harsh. He said, and I quote, “The three biggest lies in aircraft shopping are: 1- no damage history, 2- no corrosion, 3- the engine temperature and manifold pressures have never gone above red line”.

Be a smart buyer. Considering the age of the fleet, these three comments are likely true today and worthy of your attention. Until next month, fly safe!

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