Does prop strike = mandatory engine overhaul?

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Lotro
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Does prop strike = mandatory engine overhaul?

#1 Post by Lotro » Wed Nov 23, 2016 3:34 pm

If I have a prop strike (I didn't), I know the damage has to be repaired and engine inspected. What I don't understand is whether or not an inspection is sufficient, or if it's really an overhaul and people call it the same thing.

Thanks for your help.
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Glasnost
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Re: Does prop strike = mandatory engine overhaul?

#2 Post by Glasnost » Wed Nov 23, 2016 3:52 pm

Any time a the prop can't be repaired by field dressing due to a strike, an engine tear down is required.

A tear down and prop strike inspection is not an overhaul. Overhaul is where they check all of the dimentions and determine they are within limits for another tbo or replace the parts. Teardown is just splitting the case and inspecting the components like the crankshaft for cracks and runout. All new bottom bearings are put in, but everything else is left as is. It's about 10-15 grand difference tear down vs overhaul on a small engine.
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plhought
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Re: Does prop strike = mandatory engine overhaul?

#3 Post by plhought » Wed Nov 23, 2016 5:27 pm

Double check with your engine manual for specific inspection instructions as well.

For example, some free-turbines a prop-strike may result in changing the prop, but just a couple borescope and filter checks too allow you continue.

There's also a difference between a prop-strike and sudden-stoppage. A bird smacking a prop may require you to change prop but nothing much else - provided engine hasn't ingested remains. Smacking a GPU with a prop though would likely result in an engine change though. Either way - usually the inspection will not be the same as a true overhaul - as noted above.
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Lotro
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Re: Does prop strike = mandatory engine overhaul?

#4 Post by Lotro » Wed Nov 23, 2016 6:32 pm

Thanks for the clear answers, and also for not making fun of me for not knowing. I truly appreciate it.

~Lotro
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crazyaviator
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Re: Does prop strike = mandatory engine overhaul?

#5 Post by crazyaviator » Wed Nov 23, 2016 9:37 pm

i know the lyc/cont msb s for prop strikes but does anyone know of any document requiring a teardown insp for private/ homebuilt/exp a/c ?
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cgzro
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Re: Does prop strike = mandatory engine overhaul?

#6 Post by cgzro » Wed Nov 23, 2016 10:55 pm

My understanding, at least with Lycoming, is that the accessory gears are fragile to a sudden stoppage . More so than the crank/cam. If you get a stress riser in one of the gears it would be bad news down the road.
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crazyaviator
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Re: Does prop strike = mandatory engine overhaul?

#7 Post by crazyaviator » Wed Nov 23, 2016 11:20 pm

I looked further and EA.AC-13A chap 8 indicates stoppage within 1 revelution requires internal insp. Of course dial checking, acc case bits, accessories and gen ext visual are needed as well as detuning crank counterweights. If a private is runnning an 0-200 and is therefore not obligated to follow any mandated SB s , then it may be as little as an external inspection and signoff by an AME if the prop is lightly damaged without sudden stoppage ,,,, MOST AME s will want a teardown and MSB compliance for more than the threshhold MSB requirements
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HiFlyChick
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Re: Does prop strike = mandatory engine overhaul?

#8 Post by HiFlyChick » Fri Dec 16, 2016 8:47 am

Although an O/H isn't necessarily required, any time you have to split the crank case it's really expensive, so depending on the number of hours left to O/H it might make sense to just go ahead and do the full O/H. We haven't had a prop strike, but had to split the crank case one time due to another fault (I think it was a split shaft for the prop governor). If you calculated the cost against the hours remaining vs. a complete O/H, it ended up making sense just doing the full thing. (Although in that case, it was a new-to-us aircraft and we had had trouble with the other engine that had been O/H by the same shop, so we were also buying peace of mind in knowing we now had a reliable engine)
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