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  #11  
Old 06-29-2022, 08:10 PM
mechmike mechmike is offline
 
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  #12  
Old 06-29-2022, 10:56 PM
mechmike mechmike is offline
 
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  #13  
Old 06-30-2022, 08:26 AM
lr172 lr172 is offline
 
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Quote:
Originally Posted by mechmike View Post
Photos should be in attachments.
Ouch! What does the crank surface look like that is touching those thrust surfaces on the case? Have you figured out what is causing that gouging? Odd that you are getting damage on both the fore and aft thrust surfaces. Something definitely not right.

Larry
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Last edited by lr172 : 06-30-2022 at 08:28 AM.
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  #14  
Old 06-30-2022, 10:34 AM
TS Flightlines TS Flightlines is offline
 
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yep, apparently the case halves arent square.
I defer to the engine assembly specialists on VAF.

Tom
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  #15  
Old 06-30-2022, 01:02 PM
theduff theduff is offline
 
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Default Misaligned Cases

Quote:
Originally Posted by lr172 View Post
Ouch! What does the crank surface look like that is touching those thrust surfaces on the case? Have you figured out what is causing that gouging? Odd that you are getting damage on both the fore and aft thrust surfaces. Something definitely not right.

Larry
Iím with Larry on this one. I would send the case back to DIVCO and have them explain the misalignment. Good chance this case goes to the dumpster. At this point another case seems the prudent move. I know the case shops can do amazing jobs of welding and remachining but with these issues itís best to start clean.
Duff
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  #16  
Old 06-30-2022, 01:09 PM
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Mike S Mike S is offline
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Quote:
Originally Posted by mechmike View Post

This is a freshly rebuilt certified case (and rebuilt engine). Just sorting out what on earth to do now.



Mike
Methinks I would be looking for warranty coverage.
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  #17  
Old 06-30-2022, 01:53 PM
lr172 lr172 is offline
 
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Originally Posted by theduff View Post
I’m with Larry on this one. I would send the case back to DIVCO and have them explain the misalignment. Good chance this case goes to the dumpster. At this point another case seems the prudent move. I know the case shops can do amazing jobs of welding and remachining but with these issues it’s best to start clean.
Duff
And what is interesting is it does not look like misalignment that is causing the damage, though it does appear to be misaligned. If that were the case. the wear surfaces would be relatively flat and clean, just offset a bit; WIth everything right, I doubt you could even see uneven wear at 30 hours. something is tearing chunks out of the case surface. Can't be smooth metal rubbing doing that type of damage, especially with all the oil coming out of the journal area. Something sharp is literally tearing the Aluminum off the surface (curled metal shavings, just like a lathe). Please post pics of the crank in the mating areas. Curious if there a machining flaw there.

Larry
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Last edited by lr172 : 06-30-2022 at 02:03 PM.
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  #18  
Old 06-30-2022, 02:37 PM
PhatRV PhatRV is offline
 
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This video about overhauling a Lycoming engine shows the clearance checking before the two halves of the cases are mated and the crankshaft end play is checked, about the location where the pictures show the parts rubbed together. The time is about 10min 10 secs

https://youtu.be/n-26eqLc4pQ?t=609
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  #19  
Old 07-01-2022, 07:07 AM
mahlon_r mahlon_r is offline
 
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The mismatch at the rear journal being offset at the back of the engine isn't unusual. The areas with the damage are lubricated from oil that is pushed out of the nose bearing. It looks to me that either the supply of oil to the nose bearing was limited or the clearance at the nose bearing bore was too small or the nose bearing was defective. That would cause the clearance between the crank and the bearing to be too small which in turn would limit the oil supply to the thrust surfaces. When I was working we always made the nose bore at max new limits, thus making the bearing clearance at maximum to combat this issue. On our experimental engines, we drilled extra holes/ passages to help provide extra lubrication to the thrust surface. Time will tell the actual cause upon further investigation. Crankshaft likely has heat check cracks at the thrust surfaces and is ruined.
Good Luck,
Mahlon
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  #20  
Old 07-01-2022, 08:05 AM
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BillL BillL is offline
 
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Quote:
Originally Posted by Mike S View Post
Methinks I would be looking for warranty coverage.
+1 ohhh yeah - you betcha!! The thrust surface "could not support hydrodynamic lubrication due to poor geometry from the machined surface"

Well, Mahlon has spoken, I defer.
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