Recognizing Aircraft Engine Value

One of my first cars was a 1964 Impala SS with the 327 hi-performance small block engine. When I went onto the car lot, I saw this black beauty – complete with black interior - and fell in love.

Steve Watkins  |  01st March 2013
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Steve Watkins
Steve Watkins

Steve Watkins is Technical Services Manager, Western Region for Jet Support Services, Inc. (JSSI). Steve...

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engine on side of jet

It’s not in the eye of the beholder!

One of my first cars was a 1964 Impala SS with the 327 hi-performance small block engine. When I went onto the car lot, I saw this black beauty – complete with black interior - and fell in love.

I walked around the outside of the car admiring my reflection in the flawless paintwork. Being a diligent aircraft mechanic, I naturally had to pop the hood to see the hidden powerhouse. It opened to uncover the big chrome air filter cover and the engine looked factory-new. I started it, ignoring the little puffs of blue smoke that came out of the tail pipes, and the engine roar was music to my ears. I had found my dream car and instantly plopped down the $1,700 asking price and drove off the lot wearing a big smile.

That was the last time I smiled when thinking about that car. Within a week, the car had developed a clicking sound, and those little puffs of blue smoke were becoming less little by the mile. Within the year, I had torn down the engine (due to the massive amount of 19 cent quart bulk oil that the 327 engine was going through), and when I had the engine stripped down it became apparent that someone had filled the crankcase with oil treatment. There was a three-inch layer of sludge on the bottom of the oil pan.

The sludge explained my original false opinion of the engine along with its rapid decline that eventually saw me driving around in a haze of blue smoke. Had I known about the real condition of the engine, my ego would have still forced me to buy the car, but I am sure I would not have paid the full $1,700 for it.


It’s the inside that counts
I admit to this impulse purchase to illustrate a point: You cannot tell the condition of any engine, car or aircraft, by its outside appearance. Hiding the actual condition is rather harder to do with an aircraft, but it can be done. Research and examination of past maintenance documentation will help determine the value of the aircraft engines, which are major factors to consider when placing a value on the aircraft. Overhauls, Mid-Point Inspections (MPI), Life Limited Component (LLC) replacements, and scheduled inspections are the most important aircraft records to review when determining engine value.


Overhauls & Inspections
First, check the Overhauls and MPI over the life of the engine. Is the history of the intervals changing? Many engines have their overhaul interval requirements extended over the years, so check to see if the latest overhaul coming due has been determined using the latest interval specified in the maintenance manual. Review the Service Bulletins or other maintenance options that can be performed prior to, or during the next Overhaul or MPI that will extend the Overhaul interval. If extensions are available, then the value of the engines could be increased.

It is also important to look for reductions of interval or additional inspections that may be required. Some engine manufacturers have calendar interval inspections that are determined by the number of years since the last Overhaul or MPI, regardless of the hours or cycles flown. If you are looking at an aircraft with a history of low hours and cycle usage, it may sound good but could have a calendar engine Overhaul coming due that could reduce the value of the engines.

There could also be inspections required due to the low utilization of the aircraft. These inspections can be required, if the aircraft has not flown a certain amount of hours over a specified length of time. If this kind of inspection is required, then the engine value could be reduced.

Borescope inspections can also reduce the value of an engine… A borescope inspection is usually hourly specified and requires a look inside the engine to determine the condition. If I could have only done a borescope inspection on that Impala, I would have seen all of the wear and sludge in the engine, so my purchase price would not have been the dealer’s asking price. This is why it is always a good idea to comply with the recommended borescope inspection during a pre-buy inspection.


Life Limited Components
If, at the last Overhaul, the owner was looking at obtaining an Overhaul or MPI at a lower cost, the components could have been reinstalled. Maintenance and Overhaul manuals do not require replacement of these components until they have reached an hourly or cyclic limit, even when an Overhaul is being accomplished. It is possible to have an LLC reach its maximum life prior to the Overhaul or MPI. This allows for two options; the LLC being replaced without the inspection, or the Overhaul and MPI happening at the same time. Either way, the additional cost will effect the value of the engine.


Airworthiness Directives (AD) & Service Bulletins (SB)
ADs and SBs can require the replacement or inspection of components inside the engine. These can be calendar, hourly or cyclic requirements or they can be Part Number or Serial Number specific. The ADs and SBs are not always related to the Overhaul or Life Limit currently required by the Maintenance Manual. The requirement may be at a specific interval or require it to be accomplished at the “Next Access”.

Airworthiness Directives are created from Manufacturer Service Bulletins, therefore assuring that the latest and greatest Mandatory Service Bulletins are complied with as the best way to prevent unexpected major maintenance costs and reduction of the value of the aircraft engines.

Above I have referred generally to the engines, but you should also review all of the accessories on the engines for each of the previously mentioned maintenance requirements. One of the most reliable ways to assess the value of an aircraft engine is to look for a maintenance program that provides coverage for all the previously-mentioned requirements as they occur. These programs provide peace of mind and assurance that the engines have been properly maintained, so the protection is reflected in the engines’, and ultimately the aircraft’s value.

So when you are looking at buying that shiny, newly painted aircraft with upgraded avionics and a fresh interior, you may have to look deeper under the hood (or cowling) to assure that the value is worth the asking price.


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