Listers,
Regarding this, does this TC flag as failed? If not
that is a real problem. Otherwise, statistically you are more likely to
fail an artificial horizon than the TC. I have had two horizons fail in
2700 hours but no TC failures. The last one required me to fly partial
panel for nearly 400 miles above an overcast (tops were at 17000 and Denver was
in the midst of a sever snowstorm.
Michael Smith
From: Lancair Mailing
List [mailto:lml@lancaironline.net] On Behalf
Of VTAILJEFF@aol.com
Sent: Wednesday, October 03, 2007
6:01 PM
To: lml@lancaironline.net
Subject: [LML] Turn Coordinators
and Autopilots
For those of you that have STEC autopilot
systems please read SAIB 60-21 attached below. The STEC autopilots use
the TC for "attitude" reference. Their sales literature tell you how
much safer this is over the attitude reference systems other manufacturers use
(like King). Unfortunately, STEC does not tell you that if the TC ground wire
becomes disconnected or the TC loses the ground signal the AP will still
operate by slowly rolling the aircraft one way or another (albeit without an
attitude reference). This can pose a big problem in the cockpit if you are IMC
(the AP "ready" light is on but the TC is failed) and can cause
a pilot to lose control of the aircraft. It is my opinion that this has been
the cause of at least two fatal accidents and one serious accident. The
survivors of the serious accident -- two instrument rated pilots related how
confusing it can be to fly with the AI going one way and the TC going the other
way.
Unfortunately, STEC is currently
fighting one of these cases Federal Court in NJ where I have
testified against them and has chosen to not inform its customers of this
potentially deadly problem.