In researching a crash of a Cessna 414, I found the following just this
morning. The crash was in 2001, and the full NTSB narrative written in
2003. I found the information below very interesting as we have 3 ECi
cylinders on our Aztec.

Maybe we should think more about the heads than the cylinders.

YMMV

Jim



Excerpt from NTSB narrative:

"Lycoming makes use of only new cylinder heads and new barrels in all of its
cylinder assemblies, which are ultimately used on their factory new engines,
engine overhauls, and rebuilt engines. Lycoming does not repair any
component of its cylinder assemblies. Teledyne Continental makes use of only
new cylinder heads and new barrels in its manufacture of new and rebuilt
engines.

ECi received FAA STC (SE4408SW) approval for the repair of 38 different
Lycoming engine cylinder assemblies ranging from 320-720 series engines. The
STC authorizes ECi to repair cylinder assemblies by removing and reusing
used cylinder heads onto new ECi barrels, regardless of the cylinder head's
time in service or number of times that it had been reassembled onto a
cylinder head.

The "serviceable" yellow tags for all the cylinders from the left engine do
not make any reference that the assembly is an STC. The only regulatory
reference provided on these tags was listed as:

"Item Has been repaired by FAA approved process as follows:"

Replacement parts per FAA approved applications listing"

For product definition Refer to ECI's FAA approved Class Reference Manual."

A cylinder assembly consists of two main components, the aluminum alloy head
and the steel alloy barrel, which according to assembly procedures provided
by the FAA, are screwed together while the head is at an elevated
temperature in the vicinity of 600 ºF.