Major Overhaul

 I am a member of a flying club, and a part owner of a 1979 Piper Archer II.  When I bought my share of the Archer in Spring 2024, rough estimates showed there were about 900 hours on the engine since the last major overhaul.  For many months there were no signs that there was anything wrong with the engine.  Good news for all of us.  As we entered the fall months, and while doing the bulk of the training for my instrument rating, I noticed several times that the RPM on the tachometer at full throttle wasn’t reaching the normal number.  My Certificated Flight Instructor-Instrument (CFII) noticed it as well and we discussed that it appeared to be out of character for the airplane.  There were no other engine related red flags, no excessive oil burn, no issues with rough running, and nothing had been found on any recent oil analyses.  The airplane still flew and climbed fine.

As we were approaching the end of the year, and the annual was fast approaching, we decided to mention it to our A&P as a point of concern.  As he conducted the annual inspection, he initially noticed that the camshaft was out of specification and that the valves were not opening and closing fully as a result.  In his assessment, this would easily explain the perceived reduction in RPM we noted on the tachometer.  The initial recommendation was a camshaft replacement, which he felt would address the issues and we readily agreed as the expected cost was not terrible, and with our club structure each member would only need to pay a small amount (I plan to discuss the structure of our club in a future post).  However, as our A&P dug deeper into the engine, he noticed a few other issues that led us to a decision point that all airplane owners will eventually face.  Replace the parts that were at issue or go forth with a major overhaul.  After a logbook review, the A&P also determined that the engine was beyond the Time Between Overhaul number and had surpassed it by about 18 hours.  The 900-hour number I had been working with traced back to a top overhaul only that had been done some years back but wasn’t a major overhaul. 

With about a $9,000 difference between the two options, and with no guarantee that the problem would be solved by only replacing the parts in question, it seemed like a better option to take the hit and go with the overhaul.  After some discussion by the club board, thankfully, we settled on moving ahead with the major overhaul.

We downed the airplane for the annual at the end of December 2024, and by mid January we had decided on the overhaul process.  As anyone who has gone through the overhaul process in the last few years can tell you, it has been a bit of battle to get cylinders and other parts needed for the work, and the initial estimate was for 8-16 weeks to complete the project.  We settled on Aero Engines, of Winchester, VA, not only because our plane is based there but because of the reputation.  Tom is an excellent engine builder, with a great deal of experience.  He also did the overhaul on a plane I used to rent, and it has been a rock-solid engine which is exactly what you want when you are spending this amount of coin.  Due to changes in the law surrounding chroming in the US, we weren’t able to get new chrome cylinders and had to settle for steel.  In any case, the process went smoothly, and we had our bird back in mid March.  I flew the first hour plus on the tachometer, just orbiting the airport from above around 3,000 feet.  When I say Tom builds rock solid engines, I mean it.

As I write this today, the airplane is sitting with around 20.5 hours on the engine, and she’s had her first oil change since the overhaul with no anomalies noted.  The break-in process went smoothly and there have been no issues found otherwise.

In total, our major overhaul cost about $26,000.  Fortunately, the club did have some money in an overhaul reserve but each member was assessed $2000 to cover the other work we had performed during the annual, the installation of some new wingtip LED position lights, and a new turn coordinator (it decided to start acting up on us near the end of the year and the airplane wings just wouldn’t move better than half the time).

A key takeaway from this process is to know your engine builder.  Although I tend to think that Lycoming engines are solid, it’s important to have an engine builder with a good reputation and a sufficient level of experience.  Especially when you consider that this is one of the priciest parts of airplane ownership and certainly something you want built well.  If you don’t have a reputable engine builder at your field, call around, and see what options are available.  Prices vary widely for engine overhauls, as do the timelines for completion.  Another key takeaway is to follow the break-in process to ensure the best results.  Lycoming has published a break-in process, and your specific engine builder may have additional guidelines or recommendations based on experience.

Have you recently gone through an overhaul process with your airplane?  If so, I’d love to hear how it went.  Drop me a line at Jeff@angryoctopusaviation.com.

Clear Prop!

Jeff

‍