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Date: Tue, 25 May 1999 08:13:49 -0700
From: Brent Regan <brent@regandesigns.com>
To: Lancair List <lancair.list@olsusa.com>
Subject: Re:Forward Gear Door Failure- IV
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          <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>>
          <<  Lancair Builders' Mail List  >>
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>>
 From: n295vv

<<Much to my amazement/unamazement, I found that 8" of my center gear
door had
peeled back to a 90 degree angle and was resting against the cowling
after I
landed from a three hour trip. <<snip>>  I am considering switching to
Titanium in place of Aluminum, and this, of course is very expensive,
but may solve the problem.>>

It wont. What you need is more stiffness (You will note that I am
avoiding the obvious comment that he should rub some Viagra on his
sagging door to stiffen it ;).

Titanium has about 160% the stiffness of aluminum and about 160% the
density as well. If you duplicate the gear door in titanium it will have
the same approximate natural frequency and will likely fatigue and fail
at the same spot.

My gear door failed at the end of the stiffener during the '96 cross
country race. My solution was to taper the end of the stiffener so that
I could extend it to within 1 inch of the forward edge, increase the
door thickness to 0.080 and Hysol and rivet the stiffener to the door.
350 hours later there is no sign of failure.

Brent



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