Mailing List lml@lancaironline.net Message #38609
From: <Sky2high@aol.com>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Electrical /Hydraulic system questions lancair 235/320
Date: Mon, 20 Nov 2006 11:26:24 -0500
To: <lml>
 
Randy,
 
Flickering Lights
 
The voltage regulator is certainly a possibility.  How about a loose connection to your light dimming circuitry or a bad ground there?  What alternator, regulator and battery are you using?
 
Lo side pressure
 
It is hard to imagine the low side fluid expanding since there is so little of it available when everything is sucked up.  However, if the stops are, uh, not rigid, it is conceivable that the up side fluid pressure rise could push the piston further, maybe thru fluid expansion in the nose wheel well actuators that are heated by lower cowling air entering the well during flight.  The ambient temperature rise in the main gear wells doesn't seem high enough to have much of an effect except that it isn't helping relieve any pressures.  Maybe Chris has more useful information.  Luckily your pressures are different enough that the dump valve relieves the lo side enough to allow the pump to come on.
 
Scott Krueger AKA Grayhawk
Lancair N92EX IO320 SB 89/96
Aurora, IL (KARR)

A man has got to know his limitations.
 
In a message dated 11/20/2006 9:16:51 A.M. Central Standard Time, randylsnarr@yahoo.com writes:
I haven't posted in a while as I have been busy flying
and completing my interior.
I will post a few pics when I am completed to keep the
grinding, sanding crowd motivated.

Anyway, I was flying recently near dark and I had the
panel switch lights on. Can someone tell me why my
lights flicker with the alternator on?

When I turn the alternator off the flicker goes away.
Is this just a bad voltage regulater or something
else?
Ironicly my wifes Lexus suv started doing the same
thing. Maybe it is her fault!

2nd question. I have experienced the same issue as
some have documented regarding the gear not coming
down without recycling the dump valve. I flew on
Friday and noticed something interesting.

Here are the facts:

Depart from PVU
50 deg f
4500 ft field elev
cruised at 12.5 for 1.2 hrs to a warmer place
decend to 4000 ft
new atmosphere temp near 65 f

I have gauges on the high and low side of the hyd
system
After take off they idicated low-0 and high-1300 or
so.
After decending to a warmer atmospheric conditions
both  the high and low side of the hydraulic system
had significantly risen. low 400 psi and high 1700
psi.

What happens in my case is the system pressure rises
in cruise on the high and low side. The lower side
exceeds the high pressure switch and the gear does not
come down. I open the dump valve and then close it and
the gear acts normally.

My question relates the down side witht he gear up.
It would seem to me that that side should always stay
at 0 relieving pressure back to the resevoir in the
pump.

At first I thought I may have a leak somewhere
allowing the pressure to sneak past the high side to
the low side in cruise. I do not believe that is
happening to me as both the high and low sides rise.

Can someone give me some idea where to start?

 
 
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