|
From: Dennis Johnson
[mailto:pinetownd@volcano.net]
Sent: Thursday, June 26, 2008 9:51
PM
To: lml@lancaironline.net
Subject: Runaway
Trim
My understanding from talking with the RAC guys, who make the
trim components I installed in my Legacy, is that stuck (runaway) trim is
unlikely. (Actually, they said it was impossible, but I find it hard to
use that word.)
A runaway trim seems unlikely to me too. There was
one GlaStar incident a few years back that was attributed to such a
failure while in the pattern. That incident resulted in two
fatalities, and a design change to the GlaStar trim authority.
Remembering that accident and
having experienced the muscle required to overcome the mis-trim on my ES-P even
when slowed to 90 kt, I figured I could either install a mechanical backup (not
practical) or try an electrical approach.
To eliminate runaway some installations have two buttons
that must be pressed simultaneously to activate either
direction. That eliminates runaway but not single-direction
failure. In my failure mode it was not a runaway failure: I was able to
trim nose-up but not nose-down. This new controller should allow me to
reverse the previous direction bypassing the control stick buttons. So if
after climb out I again could not trim nose-down I would be able to press
the reverse button and reduce stick pressure. At least - that's the
theory.
Robert M. Simon
ES-P N301ES
|