What kind of environment gets the pressure that high? I would suppose constant cycling of the unit would things up or pressures need to be adjusted per recommendations but summer heat is not likely the issue. My 360 is in Florida (yes it is hot) and my hydraulic pump if forward of the firewall. That is about ten inches from exhaust pipes and the most heat influence seen has been about 250 psi higher on both sides (gauge readings about 950 low side and 1400 high side). If they go higher, the adjustment is turned lower half a turn but that has only happen once and it was not much higher. The pump unit is not shielded or insulated although the two lines are heat wrapped where they pass six inches from the exhaust pipe. My pump unit is original (vintage 1998) and has the squarish reservoir. I think the manual specs 550 psi low side and 1100 psi high side. Something else must be wrong for pressures that high.
This looks like a relay that when it senses the Hi pressure switch being open, while the gear is up, shorts and closes the Lo pressure circuit. This will bypass the Lo pressure sensor when the sensor opens from the hydraulic fluid expanding. This type of fix does not stop the hydraulic fluid from expanding more and more as it heats up. The hydraulic fluid expansion can damage the hydraulic system. I have monitored this problem and have seen the Lo side exceed 2000 psi during this heat expansion in the summer months.
If this relay sticks the Lo sensor circuit will be on all the time regardless of the pressure sensor.
The ONLY way to approach this work around for the Oildyne pump problem is to REMOVE the pressure from the Lo side. Relieving the expanding hydraulic fluid and put it back in the reservoir where it belongs!!!!
This type of "Fix" that simply bypasses the open Lo sensor and does not relieve the expanding hydraulic fluid is insane and it's a ticking time bomb for gear failure!!!
Randy Stuart
LNC-2
----- Original Message ----- From: "Lorn H Olsen" <
lorn@dynacomm.us>
To: <
lml@lancaironline.net>
Sent: Monday, October 19, 2009 6:18 AM
Subject: [LML] LNC2 Hydraulic Gear Operation Fix
>A module to fix the gear operation failure problem in the LNC2 using
> the standard hydraulic system is now available.
>
> The problem occurs when thermal expansion has caused both HI and LO
> pressure switches to trip rendering the landing gear hydraulic pump
> incapable of operating.
>
> This module will activate the hydraulic pump motor in the direction
> selected by the gear switch when both pressure switches have been
> tripped by high pressure thereby relieving the pressure in the
> offending side.
>
> The module is 2.5" x 1.5" x .75", weighs 2.3 oz. and has two pairs of
> leads that connect directly to each pressure switch with 1/4" spade
> terminals. No other wiring is necessary. Price is $250.00 each. Simple
> installation instructions included.
>
> Contact Wolfgang at 248-471-2000 or
Wolfgang@MiCom.net
>
>
--------------------------------------------------------------------------------
>
>
>
--------------------------------------------------------------------------------
>
> --
> Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
> DynaComm, Corp., 248-345-0500,
mailto:lorn@dynacomm.us
> LNC2, FB90/92, O-320-D1F, 1,650 hrs, N31161, Y47, SE Michigan
>
>
--------------------------------------------------------------------------------
> --
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