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Date: Wed, 30 Aug 2006 19:07:09 -0400
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From: "Robert R Pastusek" <rpastusek@htii.com>
Subject: RE: [LML] Pitot-Statics
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Steve Rosenzweig writes:

I was recently tracking down a pitot leak.  Turns out I have some kind of
valve or sensor (that has two wires connected to it) that is T'eed between
the pitot and static systems.  I've verified this happens to be where my
leak is.  But what the heck is it that would be plummed between pitot and
static side?  Anybody venture a guess.

Steve,

There are a number if instruments that require both static and dynamic (e.g.
pitot) pressure inputs, and you didn't say what model of Lancair you're
flying? If it's an IV or IV-P, the device you're talking about may be part
of the landing gear downlock system. Specifically, the IV and IV-P were
designed with a pitot pressure-operated electrical switch that powers a
solenoid when above a pre-determined air speed so you can retract the gear.
See page 32-35 of the Lancair Builder's Manual, or Lancair Avionics drawing
#725, 5 Dec 2000. Not sure these are the latest Lancair references, but if
we're talking about the same thing/same type Lancair, the device is PN 710,
and called a "Airspeed Safety Switch" on the drawing.

By the way, if this device is functioning as designed and you bypass it or
cut it out of the system, you won't be able to raise the landing gear after
takeoff.

Bob Pastusek