Mailing List lml@lancaironline.net Message #70515
From: Greenbacks, UnLtd. <n4zq@verizon.net>
Subject: LNC2 Gear Pump
Date: Thu, 07 Aug 2014 19:07:48 -0400
To: List Lancair Mailing <lml@lancaironline.net>
Hey guys, I have attached an excel spreadsheet showing the hydraulic pressure data for nine flights from March 5, 2013 through August 6, 2014.
The data for the first 6 flights seem fairly typical, and I would expect minor changes due to altitude/temperature differences.
The flight on July 11th for example had the gear coming up at 7:21:12am with the pump shutting off at 1440psi. and slowly dropping to 1080psi at 7500ft
where Bill Harrelson aka Wineaux and I conducted a first GAMI lean exercise. Not sure why some residual pressure seems to remain on the low side.
Perhaps one of you can shed light on this.
The first indication of any irregularity occurred on the 7/31 flight at 9:49:09am when the pressure had dropped to 850 and the pump came on. The on cycles were momentary
for the remainder of the flight but came with greater frequency.
For the last flight on 8/6, the gear came up with the pump shutting off at 1470psi and I climbed to 2500ft, pressure immediately began to drop and the pump cycled again at 860psi
and the recycle events came with greater frequency.

So at this point, there is no evidence of any external fluid leaks. I’m thinking there may an internal leak in one of the six actuators, an issue with the pump itself, or possibly….
a failing high pressure limit switch.

Any comments and advice from all you hydraulic wizards is gratefully appreciated.

Thanks,

Angier Ames
N4ZQlml

This file only contains the last three flights due to the size of the original not being accepted on LML.
The complete file is posted to Lancairtalk.net.

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