Longest after TBo

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tltpod

Filing Flight Plan
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tltpod
What is the longest time/hours for your engine over 1000 beyond TBO?
 
An A&P acquaintance who owned an FBO and flight school did a field overhaul on his 172’s O-360 at 3000 hours, just out of caution. He said every part was still within factory tolerances. The plane flew six to seven days a week year ‘round, often a couple flights a day.
 
Just goes to show how well a 150 hour endurance test really is.....to determine a calculated TBO.
 
80hp Rotax 912. Went 4300 hours over TBO.
 
Doc has me beat, but under similar circs. O-300 in a very popoular rental C172F, ran to 4400 hours before making metal (1800 TBO) :)

We also took a IO-470K (225hp) to 3600 (1500 TBO), whereupon it spun a main bearing.

My last IO-550 was swapped for an OHE at 2300 hours (1700 TBO) and it was purring like a kitten. I feel I lost value there, but it was "starting to whisper" via some of its accessories needing attention, so it was probably the right move.

Hoping my other 550 (currently 1550 SMOH) has the same quality the first had. I'd love another 750 hours from her.
 
I’ve known of a couple O-300s that are just a little short of Doc’s Record.

Both had new jugs tough.

If I change all cylinders the rod bearings will be on the list as well.

That’s about as far you can go without splitting the Case.


On the Lycoming side:

O-320 H ( yes an H) did about 3200 of training and banner towing.

Then it went on a Glastar for some time.

Next it flew NY to Alaska and back.

Flew a bit more until owner went to Lycoming Engine School.

IIRC no jugs were pulled.

I think still short of Doc though.
 
flew a Cherokee 151 Warrior that was at 2400 total time before we chose to upgrade it to a 160. I had never been touched or even had a cylinder.
 
How about calendar time? My O-470R lasted 250 hours beyond TBO and 33 years since last major. Calendar time aging was becoming a factor plus needing 2 cylinders and a 3rd heading south and some gaskets needing service; decided to overhaul in 2022 instead of fix. Very glad about that decision since the overhaul costs soon after jumped almost 50%.
 
What are the telling signs of an engine overhaul is due?

My mechanic is more cautious, when a part is acting up, he’s like get a brand new one. He’s been saying that the engine is old and I should do an overhaul soon. I’ve met other mechanics while traveling who said the engine is fine, no signs of leaking oil. The only time I have an oil leak is when I put 6.5-7qt in (after cleaning the belly all that oil no fun, I won’t make that mistake again), or if I am not careful with the dipstick that cylinder tube that the oil dipstick goes in unscrews a few degrees (prob need to redo the safety wire and add a new o ring or whatever is there) and then there’s some residual oil there. But other than that if I keep 6qt in, it doesn’t burn any oil, I do the oil changes and cut open the filter, no metal. Before my mechanic I think said to keep 7qt and the previous owner IIRC said 7qt but he didn’t fly it much (10hrs/year), but then at 7qt it burns (or throws overboard) 1qt per 10hours tach. Usually I’ll add an extra qt (from 6 to 7) if I’m going on a long trip or if the ambient temperature is hot. I had 7 recently after Gaston’s and believe it’s down to 6.5 now as the engine oil temps were running higher down south that’s why I added the extra qt. But I think I should only add 0.5 qt next time I’m flying in the south to keep her at 6.5. Just a little more messy to add half vs full quart. :idea:

My mechanic did change I believe the cylinder seals (?) (2 of them) and said those had some corrosion on them, think that was just old maybe? I might be explaining it wrong due to my lack of understanding of an engine.

I probably should start having an oil analysis done with the oil changes, if looking at the oil filter isn’t enough.
 
Just be alert for sudden changes. It doesn't take long to figure out where an engine is happiest in terms of oil. My O-360-A4A has a max of 8 quarts (and a minimum of 2 quarts, which blew my mind when I first read it). She's happiest at about 6.5 quarts and will happily blow anything over 7 quarts all over the belly. As far as when you need to overhaul or switch components for new, I'm very much of the mind that you don't mess with something that's working well. The only things I think should be calendar/usage-based are filters, oil, and magnetos. Everything else should be done "on condition" if possible. For my money, if an engine is purring along with its usual oil and fuel consumption, count your blessings and fly on. If there's a sudden change in oil/fuel consumption, engine character (noise, RPM, vibration), or anything else raises the hackles on your neck, then go ahead and explore it. I'll be getting an engine back from LyCon at some point in the next six months and you'd better believe that I'll be far more nervous behind that engine for the first 100 or so hours than I was before it got pulled out of the aircraft. I'm far more suspicious of engines that have just had maintenance than those that haven't been attacked with tools recently.
 
AvNavCom said:
I'll be getting an engine back from LyCon at some point in the next six months and you'd better believe that I'll be far more nervous behind that engine for the first 100 or so hours than I was before it got pulled out of the aircraft. I'm far more suspicious of engines that have just had maintenance than those that haven't been attacked with tools recently.
Click to expand...

Exactly! I'd rather fly an old & trusted engine that has good oil pressure and not making metal than one that was just rebuilt or, as you say, attacked with tools recently.

Of all the ways I monitor engine health one way is to observe the idle engine oil pressure when the engine is hot after a flight just before shutdown. While oil consumption generally indicates ring wear (blow-by) or leaky valves, low idle oil pressure is usually caused by bearing wear ...
 
mandm said:
What are the telling signs of an engine overhaul is due?
Click to expand...
I've found every engine tells you in their own way. Have pulled cylinders expecting to see "A" and found nothing. For me changes in an established operating trend will get my attention.
 
I have a quite accomplished AP friend (retired airline type also) bought a diamond brand new. Has over 4k hours and still going strong.
 
I retired a O360-A4M last year at 4850 since new on original cylinders as well. Flight school utilization around 50-75 hours a month on average although before I bought it around 30-50 a month.

Also 100 hour oil changes the last 1200 hours. A/S 15w50. Only retired it because the replacement arrived so it was time to send the core in. I monitored oil samples at every 100 hour change and they came back consistent and good. Compressions all at 76-78. Can’t attest to anything else on the engine but they valued the entire core value upon inspection.
 
A number of the flight school 172s I have been renting recently are pushing 1k hours over TBO. I hear it's pretty commonplace to just keep running until they find metal in oil or lose compression.
 
I just disassembled an 2000 hour O-320-E2D for the first time since it was new about 55 years ago. My guess is that I could have R&R the cylinders, cleaned the pistons up, new exhaust valves and seats and probably run it another 5-10 year before liters and cam finally stated to each other.

(never did anything special. No cam guard. No dehydrator plugs for storage. Just put Phillips X-County and Oil filters in it) Only has ever had a oil sump preheater on it) Almost all of its life spent in an unheated hangar in the South Dakota/Nebraska area
 
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