That is very interesting and surprising. High
temperature visco-elastic creep. What is the TOT? I wouldn’t
have thought it high enough; but in any case, it suggests that intergranular
stress corrosion of the SS could also be ocurring. It may be good to
inspect the hottest portions of that pipe fairly frequently.
Al
Subject: [FlyRotary]
exhaust drift
I wanted to
tell everyone about a phenomanom I have noticed. My exhaust is drifting
backward with the force of the airstream. My exhaust comes straight off
the turbo, down and out. When first installed it used to butt up against
the leading edge of the cowl cut-out. I now have 90 hours. After
enlarging the aft portion of the hole twice over that time I finally accepted
the fact that it is slowly drifting with the force of the slip stream. It
first I was worried about the mount or the exhaust welds, but those are holding
up fine.
Last night I installed
some springs to apply a counter force forward, then I went flying (looking
for any excuse). After just 45 min of flying the exhaust forward about 2
mm. Once the exhaust is centered again I will adjust the tension on the
springs to just counter balance the force of the slip stream.
The alternative would be
to build a nice fairing around the exhaust, something I may eventually get to.