Extending Past TBO- OPINIONS please

N9091Y

I’ve just past the 2000 hour mark on my 69 Arrow. The engine is in its 12th year.

Runs fine, no oil leaks, good compressions,, and my A&P just Boroscoped, and things still look good. No spalling, etc. Also no sign of metal in the oil filter, and Avlab oil analysis came back with everything showing normal.. CHT’s are all around 375 ish.

The plan is to keep monitoring engine health through all of the above methods until it begins to “talk” to me.

How long past TBO can I keep this plan and be reasonably confident that I’m not being foolhardy? I realize this is a sensitive subject and opinions vary widely. Mike Busch sez an older engine that is running well should not be euthanized just TBO or because it’s hit that magical 2000 hour number, and that with careful monitoring and frequent oil analysis , one can safely go easily 10 pct over TBO and even more.

I appreciate all opinions .

Thanks Group N9091Y

Lon Stratton

I'm in a similar situation as you. 1800 on a TIO-540 overhauled in 2000. The engine is not speaking to me yet. However, I took a gamble on when I might need an engine based on my flying and the age of the overhaul. I ordered a Factory reman 11/22/21 with a 26-28 week delivery time. Just got word that delivery is expected 10/17/22. I'll have 90 days to return my engine if everything is still running OK. Not sure about Continental, but looks like Lycoming is running about a year on an engine. I may very well euthanize my engine, but I hope not.

Concerning the ten percent over TBO, I thought there was also a calendar time, but not sure.

mcm3m@comcast.net

FWIW I went about 10% over on my IO540 C4B5s (~2200 hrs); Nothing showing in oil filter or samples but the case seam leaks were bugging the sxxx out of me. Turns out it was about time with some lifter spalling and cam wear. I fly between 150-200 hrs/yr and have been using Camguard. Had been changing oil every 50 hrs, will probably go to 25 hrs on the oil.

N9091Y

Thanks Gents.

Appreciate the quick replies.🙂

Unit74

TBO is an arbitrary number. It’s about as accurate a measure to the engine as trying to estimate your death to the hour. Just like some people smoke, drink, do drugs, vegan, eat healthy, Exercise and so on.

Let the engine decide when it’s ready to be euthanized.

Scott Sherer

Hi fellows,

At what point does your anxiety level increase beyond normal levels with a high time engine? Only you can determinate that. Here's another issue: You need to schedule your overhaul six to nine months out. That's the lead time right now. If you have a problem and don't have a new engine coming you could be down a very long time.

N9091Y

Thank you

Rocky Landsverk

I would add this article to the mix:

https://piperowner.org/flying-past-tbo-factors-to-consider/

planewrench

Many core components on a engine are capable of going past tbo. Monitoring, as mentioned, is the key. What will NOT generally go past tbo or calendar limits are the Accessories. If you are planning on post tbo flights, at least consider everything else in the engine compartment. Hoses, mags, carbs, injection units, pumps,, they wont go another 10 years! Not to mention exhaust systems! I still find hoses that are over 20 years old on engines that have been overhauled .

N9091Y

All good points!

Mlgpilot@yahoo.com

I agree with the concept that TBO is just a made up number. In my early days working in a FBO the IA would not sign off an annual that was more than 200 hours past TBO.. Second, I checked with my insurance agent and he guessed that if the claim was not related to a high time engine or accessory, no problem, but, if the claim was the result of high time, there would be a problem paying out.

Just another point on the graph.

Mike G, A&P/IA

N9091Y

Thanks Mike. I’ve heard stories that if you have an accident resulting from an engine significantly past TBO, your insurance company doesn’t have to pay.

May be an urban myth though.I’ve never MET anyone who swears it has happened to them. Maybe a call to the AOPA is in order? Or even better- my insurance company. Let’s put it out there in the forum and see if any members have experienced this. My flight school A&.P sez that as long as the engine is properly monitored and cared for he’s never seen an insurance company not pay.

Scottvisvtuggt . I think it’s all about your personal comfort level.

morrisjd

Mike Busch, of Savvy Aviation, has several article and webinars on this topic. If interested you can check out this AOPA link:

https://aopa.org/news-and-media/all-news/2021/june/pilot/savvy-maintenance-tbo

And also this YouTube video on the subject:

https://www.youtube.com/watch?v=dXA5ZcZjJ38

Jack

N9091Y

Great

I’m a Mike Busch believer

Scott Sherer

I bumped into him at airventure this week, great guy. Regarding his opinions: They are just educated guesses. Maybe they are correct most of the time but how do you make sure that you're in the "most of the time" category? Also, I noticed that Mike flies a Cessna 310, he has two engines in case he guesses wrong, lol.

N9091Y

Yeah- 2 engines can make one a bit braver.😊

djspathis

As I understand it, unless TBO is listed as a limitation in the limitations section of the engine manufacturer's manual, it is not legally binding for part 91 operators. That said, risk tolerance is per each individual.

DJ

Digitalpilotnm

IMHO (after watching and reading Mike Busch's stuff and other peoples stuff as well)

If compressions are good, oil consumption is well within spec, not making metal, oil samples come back good, borescopes of the insides look good, fuel flow trends are good, you have something like a JPI and your CHT's haven't been abused , you fly on a regular basis, and I'm sure a few things I haven't listed, THEN for me I would keep flying until one or more trends start to tell me otherwise.

johnsouthworth

2 x TIO-540s, both now on condition. No problem as long as you monitor. I am not burning oil or using too much gas.

And yes to the accessories like fuel pumps, mags but especially turbos, alternators, needing to be done. BTW lucky you on the engine. They have just gone up 10% I noticed. The private jet guys or turboprops, if on private ops,think they can get 8000 hrs on a 4000 hr TBO. Things seems to go wrong when the new engines go in.

I would rather spend the money on avionics for safety bang for bucks.

N9091Y

Thanks all.

Grayden

I overhauled my Cherokee 140 engine at 2400 hours and it was still running good. Nothing unusual in the teardown. Bought plane with 2200 on it and saved up for a few years and was putting 80-100 hours a year on it. Just look for signs of wear.

MikeJJ

Well, those who have made it to and past TBO are the lucky ones and perhaps are in a minority? Unless your aircraft is operating close to flight school regularity, the rising expense of fuel, long lead times for parts and repairs, family commitments outside of aviation, and other sources of down time mean there is a good chance you will need engine repair, overhaul, or replacement before TBO.

So much also depends on operating habits, type of flying e.g. cross country vs. hauling parachute jumpers, and quality of engine maintenance. But I agree that the engine should tell YOU when it needs to retire, which it will, long before you experience the “heeby-jeebies” of operating over TBO if you are attentive.

Be thankful you are flying under part 91, as even though commercial operators have little issue putting time on the aircraft, going over TBO for them is NOT an option!