REFLECTOR: MT Prop failure mode.

[davedent at comcast.net]

Bernard, if the prop is OK I would look for a blockage in the intake system.

One time I had a TIO-550 with a red plug stuck in the throttle body.  It was 
left there by the factory.  It caused the same problem.  They said it 
couldn't happen but it was a three inch plug and it had actually caught 
around the valve and it didn't show till the throttle started binding.  So 
as we took the cable off the controller the controller still was sticking. 
Then we took a mirror and by looking into the (Y) of the intake we saw the 
plug.  I have pictures of it as we found it.  Continental said it couldn't 
happen.  Well it did and after removing it all was OK again.  If you find 
such a thing let me know.  Continental needs to correct this now.  This will 
be the second time it's happen.

I found on another IO-550 with two intake valves not ground at the seats. 
Zero compression after 50 hrs.  Ground the seats and all was well. 
Continental still denies it.  But this is not your problem.  I'd still look 
for a plugged intake if the prop nuts are OK>
Dave