Flight school vs. owned aircraft engine life

RyanB

RyanB

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Talking about TBO and engine life cycle, how does the time compare between an aircraft that is used for flight training vs an aircraft someone owns. The flight schools aircraft most likely will fly more often than an individual's aircraft. How does engine reliability or its life cycle compare? Do flight schools aircraft typically make it farther past tbo than the comparison or is it more of a mixed bag of results?
 
It all depends on how the engine is treated; one can find an individual owner who treats it better than a school, and vice versa. The obvious points are that the flight school probably flies it more often, which is good for the engine, but the engine may be more mistreated operationally (e.g., run beyond normal limits, not leaned properly, etc), which is bad. But without examining the engine itself and how it was run, there's no really good way to say.
 
Presuming the predominant model of wet rental applies, is poor leaning (or more to the point, any leaning) really a problem? "Full rental power" == Throttle and mixture full forward, with very little incentive for the student or renter to lean at all.
 
It is not uncommon for 4 cylinder lycomings to make tit to 2600 or 3000hrs in flight school service. Regular usage and frequent maintenance seen to trump abuse.
 
weilke said:
It is not uncommon for 4 cylinder lycomings to make tit to 2600 or 3000hrs in flight school service. Regular usage and frequent maintenance seen to trump abuse.
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That's what I've heard but it would be great if we had some actual stats to back that up. All the talk about mistreating an engine means nothing if side by side the "beat up" one lasts longer.
 
Always wondered why schools rented wet and didn't teach leaning as it seemed to incentivize the wrong behavior.

For the median student pilot, however, maybe it's just cheaper to buy gas than engines.

DJTorrente said:
Presuming the predominant model of wet rental applies, is poor leaning (or more to the point, any leaning) really a problem? "Full rental power" == Throttle and mixture full forward, with very little incentive for the student or renter to lean at all.
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GeorgeC said:
Always wondered why schools rented wet and didn't teach leaning as it seemed to incentivize the wrong behavior.

For the median student pilot, however, maybe it's just cheaper to buy gas than engines.
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I'm looking at it from the school's POV. If a school can get their engines to 2800, 3000 hrs, by cooling it with excess fuel paid for by the student - then why should they do any different? Replacing fouled plug occasionally? The alterative is that the school risks the student over-aggressively leaning (particularly considering the plane probably won't have something like a comprehensive engine monitor) at the cost of burnt valves, premature top overhaul, aircraft down time -- esp. in the good weather season when it might not be convenient.
 
DJTorrente said:
I'm looking at it from the school's POV. If a school can get their engines to 2800, 3000 hrs, by cooling it with excess fuel paid for by the student - then why should they do any different? Replacing fouled plug occasionally? The alterative is that the school risks the student over-aggressively leaning (particularly considering the plane probably won't have something like a comprehensive engine monitor) at the cost of burnt valves, premature top overhaul, aircraft down time -- esp. in the good weather season when it might not be convenient.
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Yup

Fuel is cheaper than jugs.

Also look at your demographic, people who are learning how to fly, and Johhny "I fly under 50hrs a year" renter who read on POA how cool running LOP is.

Teaching to lean it till it runs ruff, then fatten it back up is very easy and bullet proof, its been working for nearly 100 years.

I've seen a good amount of flight school plane to WAY past TBO, yeah might have to burn the plugs off once in a while, or maybe pull a couple of em, no biggie.
 
Jaybird180 said:
That's what I've heard but it would be great if we had some actual stats to back that up. All the talk about mistreating an engine means nothing if side by side the "beat up" one lasts longer.
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This is based on n=3 of flight school owners I know socially and dozends of engines they have run to TBO between them. I am sure overhaul shops have data on this but I have never seen it published.
 
Ryanb said:
Talking about TBO and engine life cycle, how does the time compare between an aircraft that is used for flight training vs an aircraft someone owns. The flight schools aircraft most likely will fly more often than an individual's aircraft. How does engine reliability or its life cycle compare? Do flight schools aircraft typically make it farther past tbo than the comparison or is it more of a mixed bag of results?
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It's a mixed bag. Remember, an engine has 2 TBO values, hours and years (typically 12 years). In light of this, you can see that most aircraft engines in Pt 91 use go far beyond TBO. It is not uncommon for a busy flight school to put 3 or even 4 thousand hours on a 2000 hr TBO engine. It's also not uncommon for it to happen in 3-4 years. You can also find people running a 30 year old mid time engine. Care and storage plays a large factor in going over calendar TBO.
 
Then again.....a lot depends on how it's flown. How is maintained. Many unravel before TBO, costing big dough. A crap shoot for sure when buying a used aircraft.
 
Chief pilot at my school said the engine failure rates are the most, when an engine is first rebuilt and then drops off from there. What are failure rates for engines well past TBO like some of these you mention? Would be interesting to find out
 
Ryanb said:
Chief pilot at my school said the engine failure rates are the most, when an engine is first rebuilt and then drops off from there. What are failure rates for engines well past TBO like some of these you mention? Would be interesting to find out
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I would say the majority of engines get overhauled before failure.
 
I would imagine that most are overhauled right around TBO, plus or minus a few hours. For someone flying charter I would think they would watch this carefully due to insurance coverage. The only shuttle operation I know about sent their engines out for rebuild. The shrike and the bonanza 36 had many incidents, cylinder came off in flight, IFR, bonanza landed at small airport ,enroute, no injury. Shrike lost engine going into Danbury, etc. no injury, etc. etc. lots of replaced cylinders.
 
Any commercial operator has to abide by TBO numbers with limited, program supervised, extensions.
 
My $.02 worth or in aviation units, $3. When I flew in Alaska, Cherokee 6
with some type of big Lycoming (it was 13 years ago, I forgets) they had us run the engines rich, like 18 gph? Does that sound high, it might have been less? Their claim was they always made TBO on the engines and it was 135 so they had to do something. My opinion was it always seemed like we were pumping lots of gas through the engine but those airplanes probably flew 700 hours per year.
 
Henning said:
Any commercial operator has to abide by TBO numbers with limited, program supervised, extensions.
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Pretty much puts the 141 flight school out of the equation doesn't it.?
 
Tom-D said:
FTFY.
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Kind of, most of the time I saw people sending engines off they had a failure that didn't need a major, but they took that failure as well as time as a sign to go ahead and overhaul. Overhaul is an economic decision as well as mechanical. Most engines you could run 3 cycles without doing an overhaul by just changing out some bearings, cylinders, and other components. Thing is there is no residual value in repair costs, while there is residual value in overhaul. If you never plan to sell, overhaul makes less sense than IRAN.
 
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Ryanb said:
Chief pilot at my school said the engine failure rates are the most, when an engine is first rebuilt and then drops off from there. What are failure rates for engines well past TBO like some of these you mention? Would be interesting to find out
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With the vast majority of piston engines operated under part 91 and legal reporting requirements of engine failures being minimal, there simply is no good data to provide that information. The only thing we have is accidents due to engine failure that are reported, and as anyone with a passing knowledge of statistics will tell you that isn't the same as determining when engine failures are most likely to occur. There are not many reported failures of 7000 hour engines because there are not many 7000 hour engines in operation!

I've seen flight school engines get overhauled at 500 hours, 1800 hours, and 3000+ hours. Since none of these resulted in accidents, there are no public statistics available for them.

As mentioned by others, engines are generally overhauled at or around TBO or when a problem is noted and the owner elects to overhaul rather than repair the specific issue. We have no way of knowing if these engines would have run 5000 hours with minor maintenance or would have died the next day.
 
weilke said:
It is not uncommon for 4 cylinder lycomings to make tit to 2600 or 3000hrs in flight school service. Regular usage and frequent maintenance seen to trump abuse.
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I have a 4 cylinder lycoming, but it doesn't make tit. I guess it's a good thing since my wife would make me sell the plane if it did :lol:
 
rbridges said:
I have a 4 cylinder lycoming, but it doesn't make tit. I guess it's a good thing since my wife would make me sell the plane if it did :lol:
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Yeah, a 4 cylinder lycoming doesn't get you tit. A jet maybe.
 
GeorgeC said:
Always wondered why schools rented wet and didn't teach leaning as it seemed to incentivize the wrong behavior.
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From what I've seen, the instructors at the schools here do teach leaning.
 
Our flying club had the 172 that was used for most of the primary training going strong 2600 since the last major (and that was the second overhaul on the engine). Unless you've got people doing really stupid things, a later model 172 fares better in a situation where it flies more. Of course the engine savings is deprecated by the tire budget :)
 
rbridges said:
I have a 4 cylinder lycoming, but it doesn't make tit. I guess it's a good thing since my wife would make me sell the plane if it did :lol:
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If Lycomings made tit there would be one in every bachelor pad....:rofl: I wonder if a 720 would make a pair of tits?
 
My limited, personal experience has been that flight school and 135 commercial operators do better than personally owned planes. These engines like to be run hard (not too hard) and often. The private fleet rusts.

There will always be variations and I'm sure some private owners will disagree.
 
jonnyjetprop said:
My limited, personal experience has been that flight school and 135 commercial operators do better than personally owned planes. These engines like to be run hard (not too hard) and often. The private fleet rusts.

There will always be variations and I'm sure some private owners will disagree.
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That would be my thoughts as well
 
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