"av8tr" wrote in message
oups.com...
My partner and I just purchased a Piper Warrior from California. All
the compressions on the engine are 72 or better. We test flew for about
two hours and found no problems. Just recently she was taken in for the
Canadian inspection. The AME in Brampton told us that the compressions
were good but one cylinder was cracked. What I would like to know is
how can you have good compressions with a cracked cylinder.


It is very simple. I did an annual inspection on my 182 before leaving for
Oshkosh and on the way home a cylinder cracked to the point that the intake
and exhaust manifolds were the only thing holding it onto the engine.

Depending on where the crack is, it could be completely below the piston
rings (as was mine) and you would never notice it on a compression check.
Even with a mirror inspection (as was mine) you could not detect an
incipient crack that had not yet broken through the surface of the cylinder
wall.



Also how
can you determine that a cylinder is cracked without dismantling the
engine.

If the crack is all the way through the cylinder, you can certainly see an
oil line that would bear further investigation. If it is NOT through the
cylinder, the only way is to do an internal AND external visual AND
particle/glow/xray inspection of the part in question (removal from the
engine necessary).


The aircraft is a PA28-151, with a 0-320. If anyone can clairfy
this issue I would really appreciate it. Can you fly the plane this way
or is it dangerous.

YOu can't be serious, can you?

Jim