So I understand TBO on the Lycoming O-360 is 2000hrs OR 12 years whichever comes first. What are your thoughts on engines that were overhauled a long time ago and technically out of time, but not hours. I'm looking at one that was overhauled 20 years ago with 575 hours since. Chrome cylinders and I was told its flown infrequently, but it flies here and there and was just up 2 months ago. In addition, the genius owner ground runs it (ugh... why...) periodically when its not flying. I'm certainly going to do a very thorough prebuy, but I'm wondering if this is something I should run from without bothering. Its not located close to me so its not easy to personally inspect.
Engine TBO (years, not hours) question
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ifly4fun
Line Up and Wait
I'm flying on a 1992 OH with about 575 hours. Runs great, great compression, doesn't burn any oil.
Dan Thomas
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Dan Thomas
I'm familiar with an 18-year-old Lyc with under 300 hours on it. It was periodically ground run. The cylinder walls were pitted and the gear train was rusty. Didn't pull a cylinder to see the cam; there was enough reason to replace it.
Good to hear. At a minimum I'm thinking I need to negotiate room for some new hoses and various other parts to freshen it up if everything looks good inside. I was just wondering if they start to go downhill fast after 20 years.
Mine's a 1996 overhaul now at 1200 hours. Runs great.
Stearman
Pre-takeoff checklist
Curious...why is that? Not high enough RPM? Oil doesn't get warm enough?
Without knowing more about it's condition, treat it as a run-out engine that will be need to be replaced. If it is in condition for safe flight any time you get flying it will be gravy.
It's a total crapshoot. You'll find 40 year old overahauls that are in great shape, running like a top, and you'll find 200 hour engines overhauled last year that are full of problems. Calendar time and hours mean very little; borescope, compression test and how it runs will tell the real story.
Makes sense, thanks.
yup. the moisture created by combustion doesnt burn off because the engine doesnt get hot enough and isnt put away hot... or at least thats how it was explained to me.
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midcap
Pattern Altitude
you would need to run it on the ground for an hour, and if that's the case, might as well go flying.
the main factor in engine health is like real-estate location!. where has it been since the last overhall Arizona or Florida ,hangar or outside, airconditioned or outside in nolo.if in the cold good engine heater . the wear on the engine is usually directly proportional to the above laundry list. however use caution as it is not impossible for a aircraft to spend time or maby all of it not were thay say it was or were it was registerted. I live in s fl and would never buy a aircraft from here it is the corrosion/ rust capital of the world .humidity is the devil. exception being a new aircraft crossion x ed regurlary , flown every day at a flight school for other than primary training hanagared and sold just at tbo or new /rebuilt engine at low time/age
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brcase
En-Route
Agree with the Crapshoot, Our Scout O-360 is 19 years since OH and 500 hours and running great, but then it has been ours for the past 12 years and we fly it regularly but not many hours per year.
On the other hand a friend just purchased an O-360 that is 19 years since OH and 500 hours he flew it 15 hours before finding a spalled cam shaft.
and then there is this in the POA Archives.
https://www.pilotsofamerica.com/community/threads/lycoming-io-540-camshaft-spalling.79678/
Brian
saddletramp
Line Up and Wait
I was a bit hesitant to buy my 182 last July because of the same issue. The 0-470 in the airplane had been overhauled in 2000 & had 450 hours on it since. The compression was good, it's always been hangared, & the owners had used Avblend at every oil change (they claimed that kept corrosion down).
I've run the engine around 70 hours since & it runs smooth & uses a normal amount of oil for an 0-470. So far so good.
When I bought the airplane I knew a top overhaul or major might be needed in the not to distant future. I did get a reduction in asking price due to this.
It is a crap shoot.
Just don't buy more airplane than your finances can handle.
I've run the engine around 70 hours since & it runs smooth & uses a normal amount of oil for an 0-470. So far so good.
When I bought the airplane I knew a top overhaul or major might be needed in the not to distant future. I did get a reduction in asking price due to this.
It is a crap shoot.
Just don't buy more airplane than your finances can handle.
Skip Miller
Final Approach
There are two factors to consider. You have to get the oil up to temperature while simultaneously keeping CHTs cool. At the reduced air flow of a ground run, the CHTs may be too high at the same time the oil is too cool.
What kind of climate has it been sitting in?
I would be highly speculative about an engine that's been a ramp-rat for 2 decades.
I would be highly speculative about an engine that's been a ramp-rat for 2 decades.
edo2000
Pre-takeoff checklist
I agree that location / humidity / sea air exposure / temperature etc., are important factors. Dry air, cooler temps, stored in a hangar, flown periodically, all good things.
I once bought a O-360 Scout that only had 350 hrs since brand new (14 years old) but had not run at all for 2 1/2 years, in southcentral Alaska. At the pre-buy, the cold compression tests were perfect, all 78s or 79s. I didn't know about Lycoming cam issues then(dumb). I flew it for 90 hours, mostly offshore fish spotting flights, before the first annual. I had noticed some engine roughness toward the end of the season. At the annual, the oil screen was full of metal and my A&P/IA let me know that the engine was toast. Camshaft and tappets had corroded and spalled. Engine had to be completely overhauled ...$$$..., but it obviously could have been much worse if the engine had gone south at the wrong time.
I'm not an A&P and I have never heard of a good way to check for camshaft corrosion/pitting on a Lyc without pulling one or more cylinders. If there is a way, I would love to hear about it. One possibility(on an aircraft purchase) would be to put purchase funds in escrow, with the stipulation that the engine is good. Then fly it for 15-20 hours and check for metal in the oil filter and screens. If it looked good, complete the deal, if not, renegotiate. But that procedure would probably be as intrusive and expensive as pulling cylinders.
It's the time the engine was run at the best operating temperature that counts. Short runs don't help evaporate moisture. The same applies to short trip driving in your car.
simtech
En-Route
Any used engine is a crap shoot. Id negotiate that plane to afford a new engine if it were me. Then fly it like it is until it tells you its ready. I mean old engines with low time is bad, new engines with low times can be bad too. Infant mortality I would bet is rather high. Me personally a mid time engine done in the last decade would be ideal..its proven itself..until it fails. hahaha see nothing is immune and everything is a crap shoot. The big question is can you afford it when it fails....maybe in as little as 10 hours after ownership...maybe in a 1000 hours.
Ya know, there is one thing Mike Busch and I agree on, and that is Overhaul or replace on condition not time. I've seen engines run far beyond TBO with no adverse effects and I've seen them go belly up at half time. Much depends on the hand on the throttle and maintenance related factors. I was simply saying I would look closely at one that has sat for a long time.
tyndall
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LawnDart
Calendar time since OH is irrelevant. Doesn't matter if it's 30 years or 3 years with a bunch of sitting. Pull a jug and look inside. Pull a mag and look inside the accessory case. If everything is clean it's probably ok.
Rcmutz
Cleared for Takeoff
Agree with this. Get a good prebuy to include a boroscope. Price the plane as a runout, and anything you get from it is gravy. That is how I bought my Tiger.
oilburner
Pre-takeoff checklist
The Lycoming TIO-540-AK1A in my plane has a 2000 hr/12 yr TBO also.
I figure the 12 yr criteria is due to things like the alternator belt, which can't be a regular maintenance item because it can only be changed when the prop has been removed.
I figure the 12 yr criteria is due to things like the alternator belt, which can't be a regular maintenance item because it can only be changed when the prop has been removed.
Blueangel
Line Up and Wait
Assume a run out. Lots of extra things like exhaust, hoses, belts and so forth may need to be replaced. The engine crankcase and cylinders may be ok but the extras can nickel and dime you. So, TBO in and by itself is not the only thing. If it was done decades ago, it may cost tons of $$$ for the other odds and bits that are worn and need replacing.
AKBill
En-Route
At what point does an overhaul zero the time of the engine?
texashikergal02
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Kathy
As I understand it, the 12 years, 2000 hrs numbers that everyone puts out are not really addressed in Part 91 regulations, nor are they more than manufacturers recommendations, not mandates.
My take is more on how the plane has been maintained in that time. Has it flown regularly? And, as already pointed out, dry climate or wet, hangered or not. Oil consumption, analysis, and compressions, along with a decent flying history will tell you more about an engine than some hours in a log book.
My take is more on how the plane has been maintained in that time. Has it flown regularly? And, as already pointed out, dry climate or wet, hangered or not. Oil consumption, analysis, and compressions, along with a decent flying history will tell you more about an engine than some hours in a log book.
unsafervguy
En-Route
when it goes back to the manufacture for a zero time overhaul and they give it new logbooks. only the manufacturer can zero time an engine.
§ 91.421 Rebuilt engine maintenance records.
(a) The owner or operator may use a new maintenance record, without previous operating history, for an aircraft engine rebuilt by the manufacturer or by an agency approved by the manufacturer.
(b) Each manufacturer or agency that grants zero time to an engine rebuilt by it shall enter in the new record -
(1) A signed statement of the date the engine was rebuilt;
(2) Each change made as required by airworthiness directives; and
(3) Each change made in compliance with manufacturer's service bulletins, if the entry is specifically requested in that bulletin.
(c) For the purposes of this section, a rebuilt engine is a used engine that has been completely disassembled, inspected, repaired as necessary, reassembled, tested, and approved in the same manner and to the same tolerances and limits as a new engine with either new or used parts. However, all parts used in it must conform to the production drawing tolerances and limits for new parts or be of approved oversized or undersized dimensions for a new engine.
bob
Radar Contact
Pattern Altitude
I just bought a twin with Continentals that are 15 and 16 years since overhaul with ~400 hrs on the motors. I've only flown it twice so far so take that for what it's worth. I did negotiate a lower price considering this. The pre-purchase and annual conducted by different mechanics within a week of each other gave the engine's a thumbs up. Compression's and cylinders looked good. During the flights, oil usage is nil. Power and speeds are same as book. Time will tell but I hope and expect lot's more time on the motor's. If not, I'll have to eat it.
Checkout_my_Six
Touchdown! Greaser!
cause we all know that after 12 years the engine turns into a pillar of salt....
dmcummins
Pre-takeoff checklist
Mine had 50 hrs SMOH after 12 years when I bought it. It is now close to 17 years and 500 hrs SMOH. It's a beech Debonair with the 225hp engine. It burns about a quart in 15-20 hrs and runs book numbers.
I did discount the price due to the engine time, but now that it is flown regularly, about 100 hrs per year, I don't worry about the time it sat. I figure if corrosion was going to be a problem it would have shown up by now.
The plane came from Wisconsin.
I did discount the price due to the engine time, but now that it is flown regularly, about 100 hrs per year, I don't worry about the time it sat. I figure if corrosion was going to be a problem it would have shown up by now.
The plane came from Wisconsin.
Different things go on different time schedules. You may be able to stretch well beyond 12 years with some interim maintenance (cylinder replacement, attention to the accessories),etc... In fact there's nothing directly time limited either by time in service or calendar time. It's just that once these times have expired, it's time to take a careful look at things.
The real problem with engines that haven't hit the time in service limits before they run out the calendar limit is that it indicates an infrequently flown engine. This can have its own set of problems which means that its unlikely the engine is going to make it to the time-in-service limit anyhow (even less than twelve years).
The real problem with engines that haven't hit the time in service limits before they run out the calendar limit is that it indicates an infrequently flown engine. This can have its own set of problems which means that its unlikely the engine is going to make it to the time-in-service limit anyhow (even less than twelve years).
Ravioli
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Sort of off topic, but here it goes. If you run the engine past TBO, do you stop accruing the reserve fund? If reserving $20/hr for each of the 2000 hours to have $40,000 overhaul budget do you stop reserving at $40,000 or do you continue until the actual work is done.
I can see where if it goes way past TBO and you continue to reserve for all those hours you could spend the reserves on a factory zero time or even a factory new engine.
OTOH, if you just went well beyond TBO you might want a good field overhaul since the engine has preformed great and then keep the excess reserve and lower the contribution on the next cycle.
Thoughts?
Rcmutz
Cleared for Takeoff
You rolled the dice and came up with a 7. You did well.
Radar Contact
Pattern Altitude
I have two separate accounts. Easy for online banking where I put what I think the average annual will cost in one account each month and the engine reserve account where I will deposit time remaining to how many hours I hope to make it to till overhaul for both motors/props. If I make it past "TBO" then I will continue to put the same amount in the overhaul fund. Thought being you can never have too much money as things always seem to cost more than you think. Also, if you end up with a healthy surplus at some time it may be used for new avionics, interior or paint. Ask me again in 5-10 years and we'll see how well it worked out for me.
saddletramp
Line Up and Wait
Wow you guys are quite anal about putting money aside! Very admirable.
Me, I just throw all my extra in the bank & use it when I need it.
Just this morning my wife suggested that I cut up one of my credit cards I never use. My Response was "what if I need something for the airplane". Her response "If we have to use the credit card for the plane we don't have a big enough saving account".
Hey, at least she would never suggest not having an airplane.
Me, I just throw all my extra in the bank & use it when I need it.
Just this morning my wife suggested that I cut up one of my credit cards I never use. My Response was "what if I need something for the airplane". Her response "If we have to use the credit card for the plane we don't have a big enough saving account".
Hey, at least she would never suggest not having an airplane.
ifly4fun
Line Up and Wait
Keeping lines of credit open increases your rating. Utilization and age of lines go straight to your score.
denverpilot
Tied Down
Our engine was high years and low hours way back in the day when the first two co-owners bought it. But it had been flown hard by the second owner and oil analysis was, and has remained, flawless. That said, it's also a Colorado airplane where water doesn't like being in the air much. Dry dry dry.
dmcummins
Pre-takeoff checklist
I don't know if I would do it again. I was a student Pilot at the time and I really didn't know anything about buying a plane or what to look for. I did know that inactivity is not a good thing. But I hired two different mechanics to look it over and stressed my concernes about the engine. They gave the go ahead and the first time I even saw the plane was when it was delivered. I did my night flights in it but took my check ride in a 172 as I didn't have the hi performance and complex endorsement yet.
So far it's been a good plane, but if I were to sell it I'm sure I would take a hit due to the engine age. My plan is to wear it out first so that's not a problem.