lml@lancaironline.net Mailing List Archive

This has been covered at great length before. Some take the position that "real pilots" don't need anything but the dump valve.

I have proposed two answers,

1) replace the dump valve that only opens a port between the HI and LO sides with a dump valve that dumps back to the pump reservoir.

2) install a small electric module I make across the pressure switches that runs the pump to relieve the over pressure in the "wrong" line automatically.

Wolfgang

----- Original Message -----

From: Charles Brown

To: lml@lancaironline.net

Sent: Saturday, January 26, 2013 2:07 AM

Subject: Re: [LML] Re: Thermal influence on Hydraulic Pressure

This has happened to me even at the beginning of a flight, if the temps in the hangar have gone from cold on a previous day, to warm on flight day. I guess cold temps shrink the fluid and suck more from the reservoir into the lines, and when it warms, the pressure builds on both sides of the system, so that the "up" and "down" pressure switches are both open and the gear won't move until I pop the bleed valve.

Nasty when the gear won't retract just after blasting off into a low overcast.

Charley Brown

Legacy #299 200 hr

On Jan 25, 2013, at 7:23 AM, randy snarr wrote:

. 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.