I can relate a similar issue with my 500S.- I had one line fail due to ch
afing in the baggage area.- Boy was that a mess when the fluid erupted in
the baggage compartment.- Shortly thereafter another line failed just be
yond the repaired one and it was due to an improper flare from a previous r
epair.=0ADon=0A=0A=0A=0A=0A________________________________=0AFrom: Chris <
cschuerm@cox.net>=0ATo: commander-list@matronics.com=0ASent: Sun, November
15, 2009 9:15:52 AM=0ASubject: Re: AC-680FLP Hydraulic line
t>=0A=0ARay Mansfield wrote:=0A> In other words, is this going to be a prob
lem in the next hours of flight or next years of flight. Does anyone have e
xperience here?=0A=0ARay,=0AIf the line failed right at the flare, it was p
robably 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 differen
t flare angle than copper lines.- The tool you'll find at your local hard
ware store to flare line ends is for copper only and makes too sharp an ang
le for aluminum.- This causes cracks to form.=0AYou also mentioned that y
ou've been repairing corrosion in other areas.- The aluminum used for air
craft lines is fairly prone to corrosion.- It also "work hardens" from vi
bration and becomes more brittle with age.- You may simply be dealing wit
h aging aircraft issues.- During my commander restoration, we ended up ha
ving to replace virtually every hard line in the airplane for these reasons
.- I'd suggest a very careful inspection of all your hard lines - especia
lly 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 allo
wed to vibrate due to old, worn-out supports, that can lead to rapid fatigu
e cracking.- Clean the lines carefully with scotch bright and look for co
rrosion pitting.- Even small pits lead to failure.- Look for any areas
where the lines are chaffing (usually due to something coming loose) and ad
dress those areas immediately.- It's all just part
of being the care-taker of a complex old airframe.=0A=0Agood luck,=0Achris
- - - - - - - - - - - - -Matt Dralle, List Admin.
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