Randy,
I have spent too much time trying to analyze your hydraulic "fix".  You say "The ONLY way to approach this work around for the Oildyne pump problem is to REMOVE the pressure from the Lo side. Relieving the expanding
hydraulic fluid and put it back in the reservoir where it belongs!!!!
This type of "Fix" that simply bypasses the open Lo sensor and does not relieve the expanding hydraulic fluid is insane and it's a ticking time bomb
for gear failure!!!"

In fact, it appears to me that your circuit DOES bypass the open low
pressure switch, which starts the pump and ADDS pressure to the low side.  Then, when the high pressure switch drops out, it immediately reverses the
pump to restore the up pressure.

If this analysis is incorrect, please let the group know.

Bob Belshe EE '61
Lancair 235/320 900+ hours

PS:  Why do you think so many Lancairs, including mine, have never
experienced this problem?


-----Original Message-----
From: Lancair Mailing List [mailto:lml@lancaironline.net] On Behalf Of Randy
Sent: Monday, October 19, 2009 10:38 AM
To: lml@lancaironline.net
Subject: [LML] Re: LNC2 Hydraulic Gear Operation Fix

This looks like a relay that when it senses the Hi pressure switch being
open, while the gear is up, shorts and closes the Lo pressure circuit. This
will bypass the Lo pressure sensor when the sensor opens from the hydraulic
fluid expanding. This type of fix does not stop the hydraulic fluid from
expanding more and more as it heats up. The hydraulic fluid expansion can
damage the hydraulic system. I have monitored this problem and have seen the
Lo side exceed 2000 psi during this heat expansion in the summer months.
If this relay sticks the Lo sensor circuit will be on all the time
regardless of the pressure sensor.
The ONLY way to approach this work around for the Oildyne pump problem is to
REMOVE the pressure from the Lo side. Relieving the expanding hydraulic
fluid and put it back in the reservoir where it belongs!!!!
This type of "Fix" that simply bypasses the open Lo sensor and does not
relieve the expanding hydraulic fluid is insane and it's a ticking time bomb
for gear failure!!!

Randy Stuart
LNC-2