Message-ID: <010c01bfe8f6$2877c540$4055d0d8@default>
From: "Ian B. Crowe" <ian.crowe@sympatico.ca>
To: "Marvin Kaye" <lancair.list@olsusa.com>
Subject: LNC2 Gear pressure  switches
Date: Sat, 8 Jul 2000 12:01:51 -0400
Organization: Corvi Trade Consultants Inc
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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Whilst not wishing to be simplistic have you made 100% certain that the
wiring is properly routed and that you have no air in the system.  The
pressure switches will never do their stuff if the system is not properly
bled.

Take a wad of paper towel and ever so carefully crack open connections at as
many points as you can, one by one of course.  You should get fluid out of
the connections and if there is any air you will see that too.  Use the
paper towel to keep the fluid away from your glass as it will penetrate it
and make it impossible to glue if you need to do it in the future.  Try that
before you assume the switches are bad.  If the switches still nag you take
them to a hydraulic repair shop and they can test them for you.

As a shop tip for those who still have to plumb and test the hydraulics this
is how I did it.

I ran all my pipes as per the schematic, put the pump/motor in place.  To a
brand new side lever hand operated grease gun, well washed out and flushed
with hydraulic fluid I added a commercially obtainable non return valve
between the gun and the hose of the gun.  (I also fitted a pressure gauge,
as I had two that I am fitting to the system) I made up a connection to fit
the pipes where they attach to the pump and then with the gun full of
hydraulic fluid I precharged the system.  A good gun can generate upwards of
2000p.s.i.  With the gun connected to the high pressure side and the system
precharged I could bleed it and raise the gear.  The low pressure side was
connected to the pump/motor and by opening the emergency gear free fall
valve I could lower the gear.  After a few cycles I reconnected the high
pressure side and used the low pressure connection to bleed that side.  The
result was that once I used the electric pump for the first time everything
worked perfectly and I had dealt with all the slight leaks.

Using this method you are able to more finely control the rate at which
things happen, there is no electric pump to pump fluid all over the place.
You can check the mechanical side of the gear for interference in all
positions by stopping pumping on the gun at any time and you can set the
sequence valves without fear of damaging something.  I did this on my own
but if I had to do it again I would look for a helper to operate the gun.  I
think I had to refill the gun at least twice before the system was full.

The gun and check valve should not cost you more than $40 to $50 and if you
have a pressure gauge on it you can use it as a test rig in the future.
Full scale deflection of 1500psi should do it.

I was dreading this phase of the job but as so often happens this was an
easy job.  I wish making the wiring neat and tidy was as easy.

Ian Crowe
IT WILL FLY ONE DAY!

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LML website:   http://www.olsusa.com/Users/Mkaye/maillist.html
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Please send your photos and drawings to marvkaye@olsusa.com.
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