Wolfgang,
Could you please provide more details on your solution options? We’re coming up on wetting our hydraulic lines and if a mod if is needed it would be
easiest to do while the system is dry…
Thanks,
Valin Thorn
Legacy Project
Boulder, Colorado
From: Lancair Mailing List [mailto:lml@lancaironline.net]
On Behalf Of Wolfgang
Sent: Monday, April 21, 2014 9:44 AM
To: lml@lancaironline.net
Subject: [LML] Re: Gear Down...INOP
The problem is caused by the hudraulic pump not operating as desired. The shuttle valve inside it comes off its end stop and traps fluid in the lines. This trapped fluid expands
with temperature increase increasing pressure in the lines and trips the pressure switches. Since the switches are now open, no electricity can get to the pump morot . . . gear failure.
There are three solutions to this problem.
1) add an accumulator to the hydraulic system.
2) rebuild and possibly modify the the pump
3) install my electric module that monitors the pressure switches and automatically runs the pump to vent the offending pressures.
----- Original Message -----
Sent: Wednesday, April 16, 2014 10:06 AM
Subject: Gear Down...INOP
I believe that I recently experienced something in my Legacy that I remember reading about but can't remember all the details. I looked into the LML archives and was unsuccessful. Could someone out there please briefly summarize the situation,
reason and any possible remedies for gear extension failure following high altitude cruise in cold air followed by a decent and landing in hot air. I seem to remember a discussion about boosted pressure in the hydraulics plumbing due to the rapid rise in
temperature which in turn had an effect on the operation of the pressure switch In my recent experience...after opening the dump valve, the hydraulic pump did run, confirming continuity to the pump. After working the nose gear into the locked position, the
landing was uneventful but I would like to avoid this uncomfortable situation in the future. Would a tweak on the pressure switch adjustment be called for here or just expect to momentarily crack open the dump valve to relieve excess pressure. Thanks for
your thoughts.