Flying beyond TBOH

cfd408

cfd408

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Aurora, Colorado
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Peter
I’m in the middle of a discussion with other pilots and potential ownership partners about flying beyond TBOH. In particular with a Beech C23 Sundowner with a 180hp Lycoming O-360. There have been suggestions that as long as there’s no unusual oil consumption, no oil leaks and no metal in the oil that there’s no reason to crack the block. Further that TBOH time can be stretched by doing a top end O/H.
Professional opinions are welcome and appreciated!
Thanks!
 
Google Mike Bush and the Savvy Mechanic on line. My engine is currently 20 years and 150 hours over TBO. Engine runs like a sewing machine. compressions are all 72-74 out of 80 and burning a quart of oil every 60 gallons of fuel. Why mess with it? Engine still makes peak static power. A new engine would provide the same performance.

All cylinders are from the last overhaul except for 1.

Oil is changed every 25 hours, and oil filter opened and inspected for metal. None found so far. If the situation changes after careful monitoring, then I'll take a different course of action.

There's no need for top overhaul's unless a lot of cylinders are out. As Bush says, Top O/H's are not preemptive. Cylinders fail when they fail, there is no ticking clock of hour in use.
 
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I’d rather fly behind a 2000hr motor than a 100hr motor... (as long as good oil samples and compressions)
 
NordicDave said:
Google Mike Bush and the Savvy Mechanic on line. My engine is currently 20 years and 150 hours over TBO. Engine runs like a sewing machine. compressions are all 72-74 out of 80 and burning a quart of oil every 60 gallons of fuel. Why mess with it? Engine still makes peak static power. A new engine would provide the same performance.

All cylinders are from the last overhaul except for 1.

Oil is changed every 25 hours, and oil filter opened and inspected for metal. None found so far. If the situation changes after careful monitoring, then I'll take a different course of action.

There's no need for top overhaul's unless a lot of cylinders are out. As Bush says, Top O/H's are not preemptive. Cylinders fail when they fail, there is no ticking clock of hour in use.
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Thanks for the suggestion!
 
The first thing I'd start with is getting the engine to run to TBO, then you can decide what to do after that. I've overhauled far more engines that haven't made it than ones that have.

But, assuming you're at TBO and everything is going ok I don't see any reason to take immediate action.
 
NordicDave said:
Google Mike Bush and the Savvy Mechanic on line. My engine is currently 20 years and 150 hours over TBO. Engine runs like a sewing machine. compressions are all 72-74 out of 80 and burning a quart of oil every 60 gallons of fuel. Why mess with it? Engine still makes peak static power. A new engine would provide the same performance.

All cylinders are from the last overhaul except for 1.

Oil is changed every 25 hours, and oil filter opened and inspected for metal. None found so far. If the situation changes after careful monitoring, then I'll take a different course of action.

There's no need for top overhaul's unless a lot of cylinders are out. As Bush says, Top O/H's are not preemptive. Cylinders fail when they fail, there is no ticking clock of hour in use.
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Just read an article of his on going beyond TBOH.. he apparently supports the notion of not fixing what isn’t broken. Thanks again
 
One more reason I left the club.

$18/hr of the usage fee was for the engine reserve. I said, "Ok, so when we get to TBO we overhaul." Then I got all this Mike Bush *stuff*
out of them. I said, "Ok, so the rate goes down since we're fully reserved for the overhaul?" No, we can use that money for other stuff.
 
I don’t get the mike bush worship. Maybe if you don’t have a lot of maintenance experience he seems to be a genius. Having said that, there’s no problem running past tbo but consider this: I recently bought a Mooney C with the original engine, 2600 hours on it, compressions good, no metal. When I tore it down for overhaul the intake tubes had 1/4” of goo in them and the sump was full of sludge that didn’t drain after a hot oil drain. In spite of being well taken care of engines will accumulate gunk. If the money is already there why not overhaul or at least take a look inside after 2200 or 2400 hours?
 
Mike Bush is not a deity, and completely get your point. He is recognized as a well regarded expert in the field and relied upon for complex cases and well regarded.

Bush's perspective is TBO is just a number and not some magical expiration date. Engine condition and careful inspection dictates when to O/H. He has saved pilots a collective fortune with not performing needless maintenance.

An engine must be overhauled when it's "time". The "time" might be before TBO for poorly managed engines or engines with defects, at TBO, or beyond TBO.
 
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I might fly a little past TBO, but for the most part I overhaul when it’s time. It’s also a great excuse to swap that 520 for a 550 etc.
 
Paulie said:
I don’t get the mike bush worship. Maybe if you don’t have a lot of maintenance experience he seems to be a genius. Having said that, there’s no problem running past tbo but consider this: I recently bought a Mooney C with the original engine, 2600 hours on it, compressions good, no metal. When I tore it down for overhaul the intake tubes had 1/4” of goo in them and the sump was full of sludge that didn’t drain after a hot oil drain. In spite of being well taken care of engines will accumulate gunk. If the money is already there why not overhaul or at least take a look inside after 2200 or 2400 hours?
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I suppose when someone has a platform from which they can speak people will listen. I don't know much about Mike Busch.. in fact I never heard his name before last week. Still what I read made sense. But I'm not an A&P. What I do know is that if cars were put on the same kind of maintenance schedule as a plane the new car market would collapse.
You as well make a valid point. Pulling a can to see the condition of the valves can be quite telling without cracking the case.
 
James331 said:
I might fly a little past TBO, but for the most part I overhaul when it’s time. It’s also a great excuse to swap that 520 for a 550 etc.
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If i had the cash reserve then sure. But as a pilot who's looking to get into his first plane I'm thinking very carefully about the upfront expenditure and trying to balance the purchase cost against time before overhaul as well as needed maintenance and upgrades that come with buying an older aircraft.
 
Paulie said:
I recently bought a Mooney C with the original engine, 2600 hours on it, compressions good, no metal. When I tore it down for overhaul the intake tubes had 1/4” of goo in them and the sump was full of sludge that didn’t drain after a hot oil drain. In spite of being well taken care of engines will accumulate gunk. If the money is already there why not overhaul or at least take a look inside after 2200 or 2400 hours?
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Would you rather fly behind a 2500 hour well cared for engine if the time since overhaul was 10 years than a 2500 hour well cared for engine with 30 years since the last overhaul? Doesn't more frequent use matter? -Skip
 
Paulie said:
I don’t get the mike bush worship. Maybe if you don’t have a lot of maintenance experience he seems to be a genius. Having said that, there’s no problem running past tbo but consider this: I recently bought a Mooney C with the original engine, 2600 hours on it, compressions good, no metal. When I tore it down for overhaul the intake tubes had 1/4” of goo in them and the sump was full of sludge that didn’t drain after a hot oil drain. In spite of being well taken care of engines will accumulate gunk. If the money is already there why not overhaul or at least take a look inside after 2200 or 2400 hours?
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Mike was actually late to the game. Look for John Deakin with Pelican Perch articles. Or George Braily as another example.
There are some philosophical differences between some of these guys, but at the end of the day Mike Busch had a better/larger microphone and gave more generic rules of thumb which are less nuanced then other experts. This is the critical difference, and a large part of why Savvy came into being and has done well. What is really ironic is most of what Mike Busch, John Deakin, George Braily and others push is old maintenance methods and concepts from WW2 and the early parts of aviation.

The goo and likely most of the sludge would be lead from avgas, and a side effect of running ROP. No solution for that but to tear down the engine to remove it. However, you run LOP most of the time, you avoid more of the build up; assuming I recall/understand why, the reason is there is no excess fuel left in the engine during the burn, the lead in the excess fuel reacts with other combustion byproducts to create the sludge.

Tim
 
I have just finished overhauling the engine in my Cessna 180. It had been overhauled twice before and had 1375 hours on it since the last one in 1984.

It was running just fine with very little oil consumption, the first clue that it was junk inside was when we pulled a cylinder that had been marginal during the last couple of annuals. If I hadn't been planning to sell the plane I would not likely have planned to replace the cylinder because it was within limits.

What we found when we pulled the cylinder was an engine that was pretty much junk inside. The cases, crank and cam were all fine so I guess we caught it before it consumed itself. The interested buyer and I mutually called off the sale and I decided to overhaul the engine and keep the plane.

My observation is that just because the engine appears to be running fine and oil consumption is low does not always mean the engine is okay.
 
cfd408 said:
If i had the cash reserve then sure. But as a pilot who's looking to get into his first plane I'm thinking very carefully about the upfront expenditure and trying to balance the purchase cost against time before overhaul as well as needed maintenance and upgrades that come with buying an older aircraft.
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Get s lower hour plane, it takes most people a LOOOOONGA time to hit TBO in a low to mid time plane
 
Paulie said:
I don’t get the mike bush worship.
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No knowledgeable and experienced maintenance professional does.

NordicDave said:
Mike Bush is not a deity, and completely get your point. He is recognized as a well regarded expert in the field and relied upon for complex cases and well regarded.
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First sentence is correct. As to the second one, he is only regarded that way by non experts.

tspear said:
Mike was actually late to the game. Look for John Deakin with Pelican Perch articles. Or George Braily as another example.
There are some philosophical differences between some of these guys, but at the end of the day Mike Busch had a better/larger microphone and gave more generic rules of thumb which are less nuanced then other experts.
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A good analysis.

What Busch is for the most part is a pretty good marketing person and good at building his personal brand. But none of his maintenance ideas are revolutionary. Neither are they not widely held by the vast majority of mechanics. His thinly veiled assertions that he is the savior of poor pilots, rescuing them from an unscrupulous aviation maintenance industry filled with fiendish mechanics out to steal their money is pure hogwash. I’m surprised he doesn’t say that we are also out to rape their women folks. Yet many people seem to swallow his load. Of course the fact that some magazines publish his articles isn’t too surprising as he also advertises in them.
 
Stickman said:
I have just finished overhauling the engine in my Cessna 180. It had been overhauled twice before and had 1375 hours on it since the last one in 1984.

It was running just fine with very little oil consumption, the first clue that it was junk inside was when we pulled a cylinder that had been marginal during the last couple of annuals. If I hadn't been planning to sell the plane I would not likely have planned to replace the cylinder because it was within limits.

What we found when we pulled the cylinder was an engine that was pretty much junk inside. The cases, crank and cam were all fine so I guess we caught it before it consumed itself. The interested buyer and I mutually called off the sale and I decided to overhaul the engine and keep the plane.

My observation is that just because the engine appears to be running fine and oil consumption is low does not always mean the engine is okay.
Click to expand...

What did you see specifically to call the internals junk? No challenging you, just curious.
 
Stickman said:
My observation is that just because the engine appears to be running fine and oil consumption is low does not always mean the engine is okay.
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Totally agree. As a general rule, something mechanical is always working before it breaks.
 
Topping a high time bottom end makes no sense to me. When I had that option I went for a major. An airplane is an asset. It needs to be managed so the value is maximized. A major will net a return on investment if you need to liquidate. A top on a high time bottom is nothing but a core in the market's eyes.
 
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