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Date: Mon, 12 Feb 2001 10:34:46 -0600
From: Brent Regan <brent@regandesigns.com>
To: Lancair List <lancair.list@olsusa.com>
Subject: Much ado about little (Nylaflow)
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>>
Nylaflow brake lines work. There are hundreds of experimental aircraft
flying that use it. The fact that it offends my engineering sensibilities
has been thoroughly stated. I replaced the Nylaflow in my airplane because I
wanted something I wouldn't worry about. Maybe I just worry too much. If you
aren't going to worry about the Nylaflow failing then you probably don't
need to replace it.

Rob writes:
<<But this point -- FAA approval -- is pretty lame.  If we only used FAA
approved
practices and hardware in our kit planes then I'd be racing you in a Cessna
172, and winning.>>

My point was that utilizing Nylaflow tubing in an aircraft brake system will
likely preclude it from being "certifiable". Since the brakes do not effect
flight performance and are critical to the safe termination of a flight,
looking to the FARs for guidance is not a bad idea. The FARs in general, and
part 23 specifically, contain a wealth of information that is obviously the
result of other peoples bad experiences. Unfortunately, part 23 is mute on
brake hoses but if you read through part 23 and then pick up a length of
Nylaflow and ask yourself "should I use this in the brake system of my
airplane" you will likely say no, as I did.

I do not believe that using materials and practices that comply with FAA
standards is such a bad idea, as doing so generally enhances safety.
Performance does not necessarily have to be compromised for safety. Using a
brake line with a strength member won't take 150 knots off of your top speed
(unless you use it to tie the tail to a tree).

It would seem that most of work associated with FAA certification is dealing
with the bureaucrats that interpret the standards and guidelines and not the
standards and guidelines themselves. We shouldn't let our disdain of
government bureaucratic process cause us to ignore the standards and
guidelines that that have evolved to help build safer airplanes. Millions of
man hours and many lives have gone before us. We should at least listen.

IMHO using Nylaflow around the petals, even for low pressure,  is a bad idea
(like you didn't already know). The presence of dirt (shoes), the
probability of a snag (more shoes), lots of flexing (brakes and rudder),
heat from the cabin heater and heat from current carrying wires that may be
bundled with the brake line, all spell failure. This is just my opinion,
worth every penny you paid for it.

Regarding hard-line, other than at the petals (obviously) here is no reason
why fixed gear aircraft can't use it all the way out to the caliper. Taking
another idea from  the automotive designers, flexibility can be added to the
line by making 1 or more 360 degree helical loops. The tube becomes a spring
that can flex in all directions. Again, my opinion, but it works for me.

Regards
Brent Regan

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