Q: I’m considering buying a 2003 Socata Trinidad TB20 that has an extremely low time of just over 200 hours. A single owner purchased it new and obviously hasn’t flown it much.
It has a 250-hp Lycoming IO-540 engine. The cylinder heads were nickel coated in 2017 after an inspection found pitting on the original steel cylinders, no doubt because it sat for some time between flights. The plane has never missed an annual inspection, so it must have been run at least once a year.
Since the cylinder coating in 2017, the plane still hasn’t been flown much, but I’m told that it never sits for more than a month without being run by an airplane mechanic for some period of time as it is hangared in a place that has a service center.
What are the risks with this low time, but older infrequently used engine?
Terry Dunlay
A: Terry, I’m going to be very honest with you and state right out of the box that I’d be very cautious about buying this aircraft.
I think you already share the same concern that I do, and that’s the fact that this aircraft has a noted history of extended periods of inoperation.
Even though the cylinders were “nickel coated” in 2017, that doesn’t give me any additional confidence that the internal components of the engine aren’t suffering from some serious corrosion.
My greatest concern is the condition of the camshaft and tappets. Since there is no pressure oil in that area and they are lubricated by splash oil only, during extended periods of inactivity, the oil that remained on the face of the tappet bodies and the cam lobes runs off, leaving the acidic properties in the oil on those surfaces, which eventually lead to corrosion. As time passes this condition can continue to worsen.
When the engine is next started, the first pass of the cam lobe over the tappet face may begin to cause metal displacement or spalling on the cam lobe and or tappet body. Once this begins, it will never self heal, but continue to spall both surfaces. If you do an oil and filter change, you’re going to see some metal contamination in the oil filter element and things usually go down hill from there.
You mentioned that this engine seldom sits more than a month without being ground run by a mechanic and this really made my hair stand on end!
Ground running an engine is probably one of the most detrimental things you can do. That’s because the temperature does not get hot enough to boil off the condensation in the oil. The only way to boil off the condensation is to fly for at least a half hour to an hour to get the oil temperature up to at least 180° F.
If I were to consider purchasing this aircraft I would want to do the following:
I’d remove the number one and number 4 cylinders. This would give you a good chance to inspect the camshaft and tappet bodies for any indication of corrosion.
You could even go so far as to remove the number 5 cylinder as well, which would allow you to inspect the entire length of the camshaft and tappets.
Of course, there is always the possibility that just removing one cylinder will give you the information you’re looking for.
As you can imagine, an in-depth inspection like this would be a considerable expense, but if it reveals severe corrosion, you’ll know not to buy this aircraft.
The only way I would consider buying this aircraft would be to negotiate a price that would allow you to have the engine overhauled or replaced with a Factory New or Rebuilt engine. For more information regarding Lycoming’s exchange engine core policy, I’d suggest you read Lycoming Service Letter 250. You may also want to contact a Lycoming distributor who would be able to discuss your options.
Your engine would only be acceptable on an exchange basis for a Factory New or Factory Rebuilt engine because of its known history of extended periods of inactivity.
Since I’ve probably already ruined your enthusiasm about buying this aircraft, let me throw out a dollar figure for a Factory Rebuilt engine. At today’s prices you’re looking at somewhere around $46,000 in exchange for your engine.
200 hrs in 16 years isn’t much, but even considering an overhaul is madness. GA aircraft sit for years. My T210J turned 50 this year. Put in mineral oil, check for metal after 10 hours. Move on with life. Rich people aren’t the only people flying out there.
I don’t necessarily agree with the ‘blanket’ statement that the potential buyer shouldn’t buy this A/C. Corrosion is serious but you’re assuming that it has this problem based solely on inactivity. MOST GA airplanes sit around a lot unless they’re used in a flight school. So what do you do … buy a high time beat up flight school airplane or a creampuff low time airplane used spradiacally?
Nothing was said as to where this airplane is OR if it’s hangared, or not. Further — and as JimH in CA referred to, Mike Busch had an excellent webinar on the subject of engine resurrection.
I summer in and keep a C172 in a hangar in WI near Oshkosh where it “sleeps” for six or more months per year. Prior to running, I remove the plugs, turn it over by hand and then by starter. While it’s sleeping, I have the engine covered and a gun cabinet heater in the cowl (not to heat it but to dry the air in the vicinity). I have an exhaust plug installed with large bags of desiccant in the pipe. I’ve done this for 15 years with no issues whatever. The engine doesn’t leak or use oil and I’ve never ever found anything in the filter media.
Further, I bought a 1967 PA28-140 with it’s ORIGINAL engine — never apart — with 2000 hours on the O320-E2A — 17 years ago. That airplane had sat for long periods after its original flight training use. I did borescopes and never found any issues. It’s STILL ! flying in the hands of a subsequent owner … now 52 years old and with over 2200 hours. In fact, when I did a borescope inspection after I bought that device, cylinder honing could still be observed.
My point is … blanket statements like this are inappropriate. SOME engines … the O320’s, for example … can sit for long periods (in the right environment) with little detriment. I consider hangaring a critical factor in the buy/not buy equation. Here in WI, we have scads of airplanes that sit with no issue at all. Now then, if it sat in FL … maybe I’d worry some. That said, MY C172 sat in a hangar there with no subsequent issues at all.
Assuming the environment that TB20 lived in was benign, if I were the seller and a potential buyer tried to get me to sell it at a price allowing an engine rebuild … I’d throw them out of my hangar and tell them not to come back.
I concur. We just bought a Saratoga with an IO540. It had been run less than an hour a month for 3 years, but had two prop strikes (??) in the logs. It had been torn down, parts replaced and put back together. If the owner had just paid for the ‘overhaul’ signature, it wouldn’t be a 2200 hr engine since major.
But, we’ve had it and the rest of the plane checked out. A bunch of minor annoying maint issues were taken care of (caused by the plane not being flown much). And it flies and responds quite well.
Just say’n’
Out of curiosity is it not possible to ground run the airplane enough to get the oil temp over 180 and boil the water off? Certainly not the best option, but if the pilot/owner for some reason can’t fly the airplane might that be an option?
Typically, no. The cylinders will overheat from little cooling before the oil gets to 180deg.
Which is another reason why ground running is a poor idea.
Even a car engine will show a normal range coolant temp of 180-205 in 5 -10 minutes, but the oil will take 30 minutes of 30-45 mph driving to come up to 180 deg .
Could you not drain the oil, and put in fresh oil to run it? You could heat the oil you just drained, and use it next time you ran up the engine. Two batches of oil.
Paul, I 100% agree with you on this hangar-queen.
However, Mike Busch recently ran an article in AOPA mag. [if it’s ok to mention this ?]
https://www.aopa.org/news-and-media/all-news/2019/march/pilot/savvy-aviator-powerplant-resurrection
The prospective buyer might try this process.