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Date: Tue, 22 Apr 2014 15:04:10 -0400
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From: Kevin Stallard <kevin@arilabs.net>
Subject: RE: [LML] Re: Gear Down...INOP
Thread-Topic: [LML] Re: Gear Down...INOP
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I hear you Wolfgang,=20

Temperature changes result in pressure changes,=20

Pressure changes can then affect the switches on the pump.=20

If the pressure switches on the pump are open, then a good course of action=
 is to open the dump valve long enough to allow the switch to close, then t=
he pump works.

So in essence, if temperature changes are the root cause, it is very likely=
 that the dump value cures it (at least for that particular instance).

I think Chris Z has a bunch of information about how I may be able to cure =
the problem on a permanent basis. =20

Thanks
Kevin

________________________________________
From: Lancair Mailing List [lml@lancaironline.net] On Behalf Of Wolfgang [W=
olfgang@MiCom.net]
Sent: Monday, April 21, 2014 10:26 AM
To: lml@lancaironline.net
Subject: [LML] Re: Gear Down...INOP

Hitting the dump valve may or may not help the problem.
It depends on how much of a temperature increase you incurred.

Wolfgang

----- Original Message -----
From: "Kevin Stallard" <kevin@arilabs.net>
To: <lml@lancaironline.net>
Sent: Monday, April 21, 2014 11:43 AM
Subject: RE: [LML] Gear Down...INOP


Do you have hydraulic pressure gauges installed so you can see the pressure=
 on the high and low side?

I suspect that quickly opening and closing the dump valve would cure your p=
roblems, because yes, there is an interaction that occurs
between the high and low side and the poppet valve in your pump.   But unle=
ss you know the pressure on the high and low side when
the problem occurs, I can't say for sure.

I've seen this once on my plane.  Hitting the dump valve quickly solved the=
 problem.

Kevin

________________________________________
From: Lancair Mailing List [lml@lancaironline.net] On Behalf Of William For=
d [willydford@gmail.com]
Sent: Wednesday, April 16, 2014 8:06 AM
To: lml@lancaironline.net
Subject: [LML] Gear Down...INOP

I believe that I recently experienced something in my Legacy that I remembe=
r reading about but can't remember all the details.  I
looked into the LML archives and was unsuccessful.  Could someone out there=
 please briefly summarize the situation, reason and any
possible remedies for gear extension failure following high altitude cruise=
 in cold air followed by a decent and landing in hot air.
I seem to remember a discussion about boosted pressure in the hydraulics pl=
umbing due to the rapid rise in temperature which in turn
had an effect on the operation of the pressure switch  In my recent experie=
nce...after opening the dump valve, the hydraulic pump
did run, confirming continuity to the pump.  After working the nose gear in=
to the locked position, the landing was uneventful but I
would like to avoid this uncomfortable situation in the future.  Would a tw=
eak on the pressure switch adjustment be called for here
or just expect to momentarily crack open the dump valve to relieve excess p=
ressure.  Thanks for your thoughts.

William Ford
N11LL


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