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From: "Lorn H. Olsen" <lorn@dynacomm.ws>
Subject: Re: Possible Gear Hydraulic System Vapor Lock 
X-Original-Date: Sat, 13 Mar 2004 08:24:13 -0500
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> From: "Christopher Zavatson" <Christopher.Zavatson@udlp.com>
>
> Lorn,
> Question.  What is the pressure in your low circuit during retraction? 
>  It should be low, perhaps 50 psi.

When I retract my gear the pressure in the low side is zero.

> This is the backpressure circuit doing its job, allowing the extra 
> fluid to bleed back to the reservoir.  Once you are airborne and 
> pressure leaks across from the high side to the low side, it should 
> continue to relieve back to the reservoir.

As rebuilt from the Oil-Dyne factory, I repeat, there is no pressure 
relief.

> I just got back from the airport where I tried to replicate your 
> scenario on my test bench.  I could not get the low side to maintain 
> any pressure while a leak was slowly bleeding across from high to low. 
>  If I let it bleed more quickly, I could hear the fluid squirting back 
> into the reservoir.  My test bench is an exact duplicate of the system 
> in the airplane but with extra valves and pressure gauges to isolate 
> and monitor the particular cylinder or cylinders being tested.

How interesting. Our pumps are somehow working differently?

> I would be curious to know what your pressure indication is on the low 
> side during retraction.  If it is at or near zero with the gear coming 
> up, you've got a real head scratcher on your hands.
> Chris

Chris, call me. I would like to talk to you about your setup. Thanks.
--
Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.
248-345-0500, mailto:lorn@dynacomm.ws
LNC2, O-320-D1F, N31161, Y47, SE Michigan

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<excerpt><fontfamily><param>Helvetica</param><color><param>0000,0000,0000</param>From:
</color>"Christopher Zavatson" <<Christopher.Zavatson@udlp.com>

<bold><color><param>0000,0000,0000</param>

</color></bold></fontfamily>Lorn,

Question.  What is the pressure in your low circuit during retraction? 
It should be low, perhaps 50 psi.

</excerpt>

When I retract my gear the pressure in the low side is zero.


<excerpt>This is the backpressure circuit doing its job, allowing the
extra fluid to bleed back to the reservoir.  Once you are airborne and
pressure leaks across from the high side to the low side, it should
continue to relieve back to the reservoir.

</excerpt>

As rebuilt from the Oil-Dyne factory, I repeat, there is no pressure
relief.


<excerpt>I just got back from the airport where I tried to replicate
your scenario on my test bench.  I could not get the low side to
maintain any pressure while a leak was slowly bleeding across from
high to low.  If I let it bleed more quickly, I could hear the fluid
squirting back into the reservoir.  My test bench is an exact
duplicate of the system in the airplane but with extra valves and
pressure gauges to isolate and monitor the particular cylinder or
cylinders being tested.

</excerpt>

How interesting. Our pumps are somehow working differently?


<excerpt>I would be curious to know what your pressure indication is
on the low side during retraction.  If it is at or near zero with the
gear coming up, you've got a real head scratcher on your hands.

Chris

</excerpt>

Chris, call me. I would like to talk to you about your setup. Thanks.

--

Lorn H. 'Feathers' Olsen, MAA, DynaComm, Corp.

248-345-0500, mailto:lorn@dynacomm.ws

LNC2, O-320-D1F, N31161, Y47, SE Michigan


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