I drove over a rabbit hole a few weeks back and had a very minor turf impact with the prop. I got the engine report back today. Crankshaft gears and magneto drive gears were damaged. I also have a spalled cam and various other bits of wear which I’ve shown below. Crank case is fretted and needs to go to the USA. More experienced contributors will obviously have a better idea of what they’re looking at than me. Now faced with £10000 to get my 1000 hr engine back or £20000 to get it overhauled. Can’t really afford either so more actively pursuing the sale of a share or two now!
Those pistons look brand new in an odd sort of way, yet damaged ?
Sorry to hear, that really sucks and very costly, I am surprised you get such damage on taxi?
I never trusted landing Mooney on grass unless I walked on it 10 times before
Do you have pictures of the prop tips?
For just a learning point of view (for me), I can’t imagine the items shown in the photos being directly attributed to an impact with turf.
I think none of the damage shown would be related to a prop strike, but regardless some of the gear teeth shown are very pitted. Those and also the cam pitting would in particular concern me. The ding in the cylinder head makes me think something solid went through that cylinder. Its difficult for me to see how the engine could be brought within service limits without it amounting to an overhaul.
@LeSving the aluminum parts look to have been vapor blasted to clean them up for inspection.
How absolutely awful to hear this, zuutroy. Especially with the run of bad luck that you’ve had with this plane, all the way.
Most of the damage is certainly not due to any prop strike. It is pitting, caused simply by rust – due to the engine standing around for ages
One cannot tell when it was standing around; only that it happened at some point. Oil analysis after the engine was started up after that corrosion, would have found plenty of iron (and other stuff) in the oil.
The ding in the cylinder head is something big that got into the cylinder. Could have come off a spark plug, but my feeling is that it looks a lot more solid than a piece of a porcelain insulator, so maybe a screw ingested via the air duct, or something dropped into the upper spark plug hole during maintenance.
AFAIK, the crankcase fretting is usually triggered by incorrect tightening of the crankcase bolts (the cylinder bolts/studs and the other bolts) and perhaps a subsequent overhaul involving badly machined crankcase mating faces.
Shock loads rarely damage anything especially if it was a soil impact which didn’t destroy the propeller. I had one in 2002 against concrete (bent the last 2cm well back and the whole airport heard it) and absolutely no damage was found.
I agree that none of that damage is prop strike related and it’s root cause is corrosion (apart from the fretting). Re-machining and line boring the crank cases is a job that plenty of UK machine shops are capable of but none, AFAIK, are CAA authorised.
My own IO 360 shockload inspection has just cost me 10k and that on an engine that had only done 6 hours since the last one!
The paradox about these findings is that if you hadn’t had that prop strike, you would likely have never known about this damage. You would likely have continued flying it just fine. Another 1000 or 2000 hours. Without complaints. It’s just that now that these things are known, people will say they must be addressed.
In other words: very likely, many of us have some similar stuff in our engines, yet we think they are running “just fine”.
Same thing with cylinder work. Once we pull a cylinder, we take the occasion to look at the lifters and cams. And that’s usually when trouble begins..
It’s like admitting you have an itchy nose to an AME. Next thing you know, your medical has been pulled because you have rhinosomthingitis!
The thing is that if you have a prop strike then you trigger various engine manufacturer SLs SBs ADs etc etc blah blah which, while not mandatory on an airworthy aircraft, will be complied with by any engine shop that gets to repair the engine.
The result is a large bill which is unquestionably for the shock load related work.
And anytime you open up an engine there is a ton on mandatory replacement parts anyway e.g. conrod bolts.
