Message-ID: <002b01c28914$d8b99f30$053b3690@dell>
From: "Root" <Root@Logan.com>
To: "Lancair Mailing List" <lml@lancaironline.net>
Subject: Fw: [LML] Almost Back Flying, Again
Date: Sun, 10 Nov 2002 18:56:53 -0500
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  From: "Christopher Zavatson" <Christopher.Zavatson@udlp.com>

Lorn,
This is starting to sound like a backwards spool valve or a high side
relief valve that is set to low.  Pressure gauges will help diagnose
this.  A reversed spool valve will cause the pump to shut off
prematurely because the high side is pushing against the mechanical work
of raising the gear plus the low pressure relief valve.  Only about half
of the normal pressure is available to bring the gear up in this case. 
The pump cycles back on after a little more pressure bleeds past the low
pressure relief valve.
While increasing the pressure setting on the high side pressure switch
may get the gear up, you may be running up to close to the high pressure
relief valve, which can also cause cycling.  If you raise the setting
just a little farther the pump will run continuously while all the flow
gets dumped by the relief valve.
Once you have the pressure gauges installed, pressurize the system in
the down direction then raise the gear.  The down side should instantly
drop to near zero.  If it stays up at a few hundred psi, your spool
valve is in backwards.  There are quite a few pumps out there that were
assembled backwards due to some kind of miscommunication between Lancair
and Oildyne.  My original '95 vintage pump was correct, but I have run
across four newer pumps which had the spool valve in backwards.
Chris Zavatson

Christopher Zavatson
Mobility Technologies
United Defense
(408)289-4329