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Nice Work Chris.. I am happy to hear that I have already done what you suggested which is to install a 3 way dump valve and run the dump line to the reservoir in a low pressure line. It has worked very well. I dont like having to open the dump valve but it is necessary once in a while especially when it is cold. The pressures on both sides of the system climb due to the engine heat and the gear sometimes will not move without dumping the pressure. Have you found a solution for this with
your research that makes the original system function without having to ever dump the pressure manually?
Randy Snarr 235/320 N694RS "Flight by machines heavier than air is unpractical and insignificant, if not utterly
impossible"
-Simon Newcomb, 1902
From: Chris Zavatson <chris_zavatson@yahoo.com>
To: lml@lancaironline.net
Sent: Tuesday, September 4, 2012 2:18 PM
Subject: [LML] Re: Thermal influence on Hydraulic Pressure
Danny,
No affect on gear movement.
I should add however that elevated high-side pressure is one of the contributing factors to gear extension failures in a standard system set up. My low pressure setting is higher than the nominal 550 psi. It is set to 800 psi to avoid the pressure spike that propogates through the system when gear down is selected.
see "Failure to Extend" on page 10 for more detail.
Chris Zavatson
N91CZ
360std
From: Danny <danny@n107sd.com>
To: lml@lancaironline.net
Sent: Monday, September 3, 2012 11:54 AM
Subject: [LML] Re: Thermal influence on Hydraulic Pressure
Chris,
What was the impact on the gear movement?
Danny
LNC2-360
N 38° 43' 25.7"
W 77° 30' 38.6"
From: Chris Zavatson [mailto:chris_zavatson@yahoo.com]
Sent: Saturday, September 01, 2012 11:32 PM
To: lml@lancaironline.net
Subject: [LML] Thermal influence on Hydraulic Pressure
-took this photo after a descent from 16.5k to 1,500 ft.
OAT went from 42 to 94 degrees.
High Pressure gauge is pegged at 2,000+ psi
-Didn't get a photo, but the opposite happened on the ramp in Spokane. After sitting for an hour, the low pressure gauge was pegged at 1,200 psi+. Spokane might not be the warmest spot in the country, but at 85 deg F, it was 55 degrees warmer than the cold soak on the previous leg.
Temperature changes have a big impact on system pressure.
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