|
|
Posted for "john wright" <n338l@gbronline.com>:
My iv-p now has 771hrs on it and it is in for annual inspection. Upon
removing the lower cowling along the lateral walls of the cowling next to
the turbos, the inner skin shows evidence of heat damage. This is an all
carbon fiber cowling with the large (Dolly Parton) exhaust tunnels. The
cowling is reinforced along the lower half with what appears to be a honey
comb layer sandwiched between the outer and inner skins. When the inner
skin is pressed on with a finger it is somewhat brittle and the honeycomb
collapses beneath the pressure. The inner skin doesn't actually crack or
flake but you can tell that it has delaminated. There is no evidence of
damage to the outer skin. The paint is not bubbled nor is there any
weakness demonstrated when the skin is pressed upon. There is another iv-p
on the field where I hangar and his is worse than mine! I called Lancair
today and spoke with Justin who said he has noticed some evidence of heat on
the factory lower cowling also, but doesn't seem to view that as having much
significance. He commented that prepreg doesn't melt until 260*. He also
mentioned that some paint the inside of their cowling with tank sealer which
he says is somewhat heat resistant and allows less air resistence to air
flow through the cowling. He suggested coring out the heat damaged core and
applying 6 BIDS of carbon fiber if I am inclined to repair it. My A&P on
the field is somewhat of a Bonanza expert and he comments that on the turbo
bonanzas there is a heat shield made out of two metal layers with
insulation sandwiched in between that bolts right on to the turbo to contain
the heat and on the cowling there is applied some type of heat reflecting
material (maybe like the firewall blanket?) to protect the skin. He points
out that the Bonanza cowling allows significantly more clearance than the
iv-p. I would like to know if anyone else has observed this on their iv-p
and has any recommendations on how to fix the problem.
John Wright
Colorado Springs
|
|