I am surprised to find out that the hydraulic lines in a aero commander
are aluminum. I would have thought that 1000psi to 3000psi lines would
be steel or SS. I manufacturer equipment that runs in this pressure
range and we always use SS 1/4" tubing and compression fittings.
It is easy to work, bends will with a tubing bender, would resist
corrosion and lots of other good features.
Would it be a big deal with the FAA to change to SS tubing?
I am not an A&P.
Tylor Hall
On Nov 15, 2009, at 7:32 AM, Donald Falik wrote:
> I can relate a similar issue with my 500S. I had one line fail due to
chafing in the baggage area. Boy was that a mess when the fluid erupted
in the baggage compartment. Shortly thereafter another line failed just
beyond the repaired one and it was due to an improper flare from a
previous repair.
> Don
>
> From: Chris <cschuerm@cox.net>
> To: commander-list@matronics.com
> Sent: Sun, November 15, 2009 9:15:52 AM
> Subject: Re: AC-680FLP Hydraulic line problems
>
>
> Ray Mansfield wrote:
> > In other words, is this going to be a problem in the next hours of
flight or next years of flight. Does anyone have experience here?
>
> Ray,
> If the line failed right at the flare, it was probably due to improper
fabrication. I've seen many cases where someone has made a line and
didn't know that aircraft aluminum lines use a different flare angle
than copper lines. The tool you'll find at your local hardware store to
flare line ends is for copper only and makes too sharp an angle for
aluminum. This causes cracks to form.
> You also mentioned that you've been repairing corrosion in other
areas. The aluminum used for aircraft lines is fairly prone to
corrosion. It also "work hardens" from vibration and becomes more
brittle with age. You may simply be dealing with aging aircraft issues.
During my commander restoration, we ended up having to replace
virtually every hard line in the airplane for these reasons. I'd
suggest a very careful inspection of all your hard lines - especially
the ones exposed in the nacelles. Make sure they are well supported and
that the adel clamps are not loose or missing. If the lines are allowed
to vibrate due to old, worn-out supports, that can lead to rapid fatigue
cracking. Clean the lines carefully with scotch bright and look for
corrosion pitting. Even small pits lead to failure. Look for any areas
where the lines are chaffing (usually due to something coming loose) and
address those areas immediately. It's all just part of being the
care-talectricwww.aeroelttp://www.buildersbooks.com/" tHELP
www.homebuip; &n=============
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