Mailing List lml@lancaironline.net Message #3476
From: Brent Regan <brent@regandesigns.com>
Subject: Re: LNC2 hydraulic hoses
Date: Mon, 27 Sep 1999 08:09:59 -0700
To: <lancair.list@olsusa.com>
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AAAAAAAAAAAAAAAAARRRRRRRRRRRRRRRRRRRHHHHHHHHH!!!!!!!!

Flex line should ONLY be used where the line needs to.... FLEX. Hoses pay a big
penalty in reliability AND weight to be able to flex. I spent ten years designing
and building hydraulic robots for hazardous environments and have been sprayed by
failed hoses more times than I wish to count. Marv is right about your plane
weighing a lot more. If I had used hose instead of hard-line on my IV it would
have added 35 POUNDS! I know because I weighed the lines before installation. I
even used stainless hard-line on the engine where ever practical. On the airframe
I eliminated 10 hoses by replacing them with hard-line; four in the wing roots,
two at the brake calipers and four at the main gear actuation cylinders. 600 hours
later and no problems.

Flex line should only be used between the gear leg and fuselage (brakes), brake
master cylinders and in the engine compartment between the engine and firewall.
ALL hoses should use swaged fittings, NOT screw on, they must be CLEANED and
PRESSURE TESTED. All hoses carry either hot oil (as in The Hunchback of Notre
Dam), fuel (obvious hazard) or brake fluid (needed for safe landings). Therefore
one can assume that the loss of any hose can cause mayhem in the cockpit.

BE SAFE, DO IT RIGHT!!!

Regards
Brent Regan


> Also, make your entire hydraulic system out of flexible hose. You can be sure
> that if you ever need to remove and replace rigid aluminum line at some future
> date, you'll wish you never put the stuff in your plane.
>
> Angier Ames
>
> [Interesting idea.... I wonder what the weight penalty would be for all
> that hose and fittings as opposed to AL tubing.  A pound here and a
> pound there....      <Marv>         ]
>

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