lml@lancaironline.net Mailing List Archive

Hi Rob,

I have posted late last year on this problem to great length.

Here's some comments on why it happens;

The failure happens with a large temperature rise, the lack of an accumulator and the failure of the spindle in the hydraulic pump to stay at it's end point in the pump body efectively sealing the fluid volume in the lines. The problem occurs when thermal expansion has caused both HI and LO pressure switches to trip open rendering the landing gear hydraulic pump incapable of operating.

A module to fix the gear operation failure problem in the LNC2 using the standard hydraulic system is now available.

This module will activate the hydraulic pump motor in the direction selected by the gear switch when both pressure switches have been tripped by high pressure thereby relieving the pressure in the offending side.

The module is 2.5" x 1.5" x .75", weighs 2.3 oz. and has two pairs of leads that connect directly to each pressure switch with 1/4" spade terminals. No other wiring is necessary. Price is $250.00 each. Simple installation instructions included.

From:	rwolf99@aol.com
Sender:	<marv@lancaironline.net>
Subject:	Wolfgang's LNC2 gear pump solution
Date:	Mon, 12 Apr 2010 14:02:40 -0400
To:	lml@lancaironline.net

Wolfgang -

What exactly *is* your solution to the LNC2 gear pump issue? I vaguely recall postings a while back but naively assumed that since my spool valve is not backwards, I would be immune to the problems that many others have. But now that I'm getting close to flying, I'm thinking that if I ignore an issue as important as this, maybe I'm just being stupid and lazy.

Could you please post again, or direct me to, your solution? I assume that it involves ensuring current flows to the pump when both pressure switches indicate "high".

Thanks. I'm at a point where adding such a circuit would be pretty easy.

- Rob Wolf

Lancair 360, building still in progress