Mailing List lml@lancaironline.net Message #36525
From: Matt Hapgood <matt.hapgood@alumni.duke.edu>
Sender: <marv@lancaironline.net>
Subject: LNC2 Hydraulic problem
Date: Tue, 04 Jul 2006 01:48:18 -0400
To: <lml@lancaironline.net>
I've got a hydraulic issue.  Had it for quite awhile, and never really figured out the correct solution.  I've gone back and read the LML and still can't find my answer, so please let me know if you have a solution.
 
Problem:  Gear won't retract after takeoff.  Pump does not cycle.  Only happens every once in awhile, typically after the plane has sat on the ground in HOT weather. 
 
Example:  flew from HPN to IGX on Friday.  Tried to fly today.  Upon raising the gear switch, the pump did not cycle and the gear did not retract.  It's been over 90 degrees for a few days.
 
My normal "solution" is to loosen a hydraulic line in a main gear well and let some fluid drip out.  This has ALWAYS solved the problem.  It's really annoying though, to have to go around, land and mess with it when I'm ready to hit the road, especially when IFR...
 
So - what's the proper solution???
 
I do have a hydraulic pressure gauge.  It's mounted immediately before the gear dump valve, and I can't read it in flight.  I am an idiot, and don't know if this is on the high or low pressure side (note that the gauge doesn't move if I open or close the dump valve).   Maybe you can tell from the attached photograph?   On the ground, I think I have discovered that the gear will retract if the gauge reads below about 1200 PSI.  Today it read 1500 PSI, and it wouldn't retract.
 
Do I have a spool valve problem?  A leaking cylinder?  Some other gremlin? 
 
This has happened for years and has not gotten any worse.  Also, I have never seen my gear cycle in flight (and I think I would, because typically when the pump starts running it causes my EC100 system to give me a low voltage warning).
 
Suggestions?
 
Thanks,
 
Matt
919-933-3295
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