Mailing List lml@lancaironline.net Message #3360
From: Dan Olsen <olsen@eai.com>
Subject: LNC2 hydraulic hoses
Date: Mon, 13 Sep 1999 16:56:50 -0600
To: Lancair List <lancair.list@olsusa.com>
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Greetings,

I am beginning fabrication of the hydraulic lines for the retracts in
my 360.  One line that concerns me is the hose that connects from the
bulkhead fitting on the closeout rib to the low pressure (down) side
of the main gear retract cylinders.  This hose length is in the range
of 4.5".  When you subtract off at least 1" for each connector you are
left with only about 2" of flexible hose.

Granted, the amount of flexing encountered by this hose is quite small,
but the Lancair hose is quite stiff and it just seems like an awfully
short run that could be prone to premature failure.

Any thoughts on alternatives?

Thanks!

Dan


[I chose to follow Orin's lead and eliminate those bulkhead fittings by
running the hoses into the cabin through a small oval hole cut into the
bottom of the closeout rib in front of the phenolic plate that supports
the inboard end of the cylinder.  I'm using the hydraulic gear door option
and the only bulkhead fitting I used was for the lo-pres side of the
sequence valve.  The hi-pres side of the sequence valve is fed from a
tee in the outboard end of the cylinder (also 'borrowed' from Orin).

I've also seen a few installations which used a large looped hose for the
lo-pres side that allowed plenty of working length (trying to shoe-horn
in a 6" OA hose assembly is a PITA), and the hose was affixed to the
inside of the upper stub wing skin, above the wheel.  BTW, I think the
magic number for hose fitting allowance is actually 1.25", not 1", so you
may wind up with less hose than you think.

There's a couple alternatives for you... I'm sure there are more out there.
One more thing... you might want to 'rough-in' all of your tubing runs
with stiff wire (like 1/8" AL) to locate all your bends before putting
bender to tube.  I did mine that way and it really simplified things.
I have a picture of the dry run, I'll upload it to the LML site's hydraulics
area for you.

   <Marv>             ]


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