Mailing List lml@lancaironline.net Message #38652
From: Lorn H Olsen <lorn@dynacomm.ws>
Sender: <marv@lancaironline.net>
Subject: Re: Electrical /Hydraulic system questionslancair235/320
Date: Thu, 23 Nov 2006 14:04:42 -0500
To: <lml>
Randy,

When the gear lever is up, the low pressure builds from the high side at cold temperatures. The high pressure builds from a short burst of the pump that you have probably not noticed.

When I fly at high altitudes, where it is cold, just about every hour on the hour the pump burps. That means that my high side pressure has gone down about 300 lbs. The pump burp just brought it back up. Where did that pressure go? It went to the low side. After a couple of hours of high (cold) flying, the low side pressure has built up to 600 lbs. At a low side pressure of 600 lbs the pump will not turn on to let the gear down when the the gear lever is pulled down. At that time I have to open the dump valve for just a split second. The pump then comes on, I close the dump valve and everything is honky dory.

I can put my plane on jacks for 2 days and not lose 1 lb of pressure in the hanger. At altitude, I believe that it is caused by the cold. The hide side leaks to the low side at a rate of about 300 lbs per hour. Again, this leak does not occur in the hanger. I believe that it is caused by the cold.

Lorn

On Nov 23, 2006, at 9:28 AM, randy snarr wrote:

Chris,
.
.
.
I am absoluteley baffled over how both the high and low sides build pressure during flight.

Thoughts?

Randy.

--
Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.
248-345-0500, mailto:lorn@dynacomm.ws
LNC2, O-320-D1F, 1,200 hrs, N31161, Y47, SE Michigan


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