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Matt,
My gear wouldn't go up, once. I have pressure gauges under the passenger seat so that I can evaluate the problem when I get back on the ground.
I was flying at about 20°F. 2 days later, when I took off, the temperature was about 50°F. The gear would not retract. After I landed and looked at the gauges, The down side which should have been 0 was around 1,400 lbs. When I put the gear down the pressure doesn't normally go above 700 lbs. The heat must have taken the pressure up past where the pumps override valves opened to keep it at the maximum of 1,400 lbs. With the pressure over 400 lbs the pump wouldn't run. The up side was also at the maximum. Are gear systems are susceptible to heat pressurization. I had to open one of the valves to let some pressure out.
If you are concerned about your gear sticking in the down position, the following is a simple test that you can perform before you start the engine.
1) With the master off, open and then close the dump valve.
This should take all pressures to zero.
2) Turn the master on and listen for the system to re-pressurize.
If the system doesn't re-pressurize, your gear won't come up after takeoff.
I haven't tried it yet but I think that we should leave the dump valve open when we park the airplane. I would have a hard time determining if this would help because I have only had my gear stick down once in 1,500 hrs.
Why do we leave the gear system pressurized when parking? If the plane were towed, would no pressure be likely to cause a gear collapse? Are the gear down springs enough to keep the gear down without hydraulic pressure?
I bought Tygon tubing from my local lawnmower repair shop for next to nothing. Tygon is the standard gas line for lawn mowers.
Lorn
From: "Matt Hapgood" <matt.hapgood@alumni.duke.edu>
Date: April 12, 2009 7:27:58 PM GMT-04:00
I am so sick of my 360's landing gear NOT retracting after taking off on a
hot day.
I've:
1. Rebuilt every single gear cylinder (some twice) and had someone double
check and pressure check the work
2. Replaced the dump valve
3. Checked for leaks
I give up. I've installed the newer legacy dump valve that can return to
the pump reservoir, but I haven't yet run a line from the valve to the
reservoir.
I was thinking of using tygon.
1. Is there any problem with this? I can't see why there would be - no
pressure
2. Does anyone have about 8' of the stuff they aren't using and would ship
me for cheap?
Thanks,
Matt
--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,550 hrs, N31161, Y47, SE Michigan
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