Re: AC-680FLP Hydraulic line problems


Subject:    Re: AC-680FLP Hydraulic line problems
From:    Tylor Hall (tylorhall@mac.com)
Date:    Sun Nov 15 - 7:22 AM
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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