Avidflyer2
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- Joined
- Mar 25, 2016
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I have a client who has experienced exhaust valves sticking on both engines - at the same time - shortly after purchasing the airplane. 10 of 12 exhaust valves stuck to the point of bending the pushrods. Both engines were topped and all was well for the next year/50 hours. Now the right engine LTSIO-360 has developed a stuck valve in its #1 cylinder. What could be causing such an unusual event especially since the short time from the last failure?
I have no idea what power settings, EGT, or CHTs are normally set by this operator. Too cold, too hot, etc…. The other engine does have a GEM but the right one has been removed, back to the OEM single probe CHT.
TCM Continental Service Manual M-O does list the overhaul, new, and service limits of the exhaust valve and exhaust valve guide. The OH and In-Service limits for the guide is specified as 0.3755 inch finished inside diameter. The valve stem may vary from 0.3712 to 0.3720 inch. This leaves a .0048 inch maximum wear limit as a worst case with .0025 to .0035 as being a fairly reasonable clearance for a mid time engine.
What is the consensus here: clearances too tight; or operator error?
Additionally the airplane was suspected of having been operated on something other than 100LL when the first failures occurred. Not so in the interim as only 100LL has been used. Surely any contaminants would be gone by now!
I have no idea what power settings, EGT, or CHTs are normally set by this operator. Too cold, too hot, etc…. The other engine does have a GEM but the right one has been removed, back to the OEM single probe CHT.
TCM Continental Service Manual M-O does list the overhaul, new, and service limits of the exhaust valve and exhaust valve guide. The OH and In-Service limits for the guide is specified as 0.3755 inch finished inside diameter. The valve stem may vary from 0.3712 to 0.3720 inch. This leaves a .0048 inch maximum wear limit as a worst case with .0025 to .0035 as being a fairly reasonable clearance for a mid time engine.
What is the consensus here: clearances too tight; or operator error?
Additionally the airplane was suspected of having been operated on something other than 100LL when the first failures occurred. Not so in the interim as only 100LL has been used. Surely any contaminants would be gone by now!
