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To:  lml@lancaironline.net
Date: Fri, 17 Oct 2008 02:25:04 -0400
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From: Lorn H Olsen <lorn@dynacomm.us>
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Subject: Re: Hydraulic Woes

> From: "GT-Phantom" <gt_phantom@hotmail.com>
> Date: October 15, 2008 1:40:30 AM GMT-04:00
> .
> .
> Questions:
> - Can anyone verify (or refute) my theory about the rapid switch  
> cycling at full extension / retraction? If not check valves, solution?

Some valve or actuator is leaking.

> - Does anyone know of a good way to completely purge the system of  
> air?

I have had my pump out a couple of times and never even thought about  
air.

> - Has anyone determined conclusively that the "recommended"  
> pressures of 1100/550 simply AREN'T enough?

These pressures are absolutely high enough.

> - How high is safe for the system if I go up on either of the  
> pressure switches?

Don't go higher. The gear should go down with 0 pressure and up with  
500 to 700.

> My prior plane was a 235 with a virtually identical system (I did  
> not build either one) and, although it might cycle once or twice at  
> the end of the retract cycle would then immediately be quiet  
> (although on a very long flight it might "burp" once or twice in the  
> up direction to maintain up pressure).

Every hour that I fly, my pump burps. Any more and you have a leak.

> All help appreciated!
>
> Cheers,
> Bill Reister

As a side note, not having anything to do with your problem, the  
temperature change at altitude or overnight can change the pressure in  
the system by up to 1,000 lbs.

--
Lorn H. 'Feathers' Olsen, MAA, ASMEL, ASES, Comm, Inst
DynaComm, Corp., 248-345-0500, mailto:lorn@dynacomm.us
LNC2, FB90/92, O-320-D1F, 1,489 hrs, N31161, Y47, SE Michigan