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1. 10:07 AM - Heat shield (dlm)
Message 1
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When the aircraft was first flown in 2008, a heat shield of fiberglass mat
with a silicon back was used to protect the lower cowl. The baffling and
sealing tape was used to properly route cooling air. The solution lasted
1100 hours and 9 years; last year I had an incident which required removal
of the baffling material from the engine. It was removed/replaced by a
third party; I did not check their work except that I did notice somewhat
higher EGTs (30-40F). I did not think this highly important. In May of
2017, I noticed a wart on the external lower cowl which measured to be
adjacent to the #6 exhaust tube which passed below #4. Upon further
examination, I found two additional area adjacent to the three-in-ones on
the bottom of the cowl. These all were delamination of the fiberglass both
inside and out due to excessive heat. After about 10 hours of removing the
old material and scorched glass, I found the Nomex honeycomb to be intact.
another 10 hours and about $300 for new materials, I had laid four
additional layers of glass inside, two layers outside, Evercoat and primer
on the outside. Further examination of the flow of cooling air, showed
misplaced/distorted baffling and no sealing tape. After
reinstalling/reshaping the baffling and replacing the missing sealing tape,
and placing Fiberfrax under an internal aluminum foil, cowl temperatures
are now below what they were prior to the original incident. *Lesson
Learned. Do not let anyone besides yourself or trusted associates touch
your aircraft otherwise check everything they do.*
*You always learn more than you ever wanted to know*
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