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On Monday I received an email and invoice that my plane's annual was
completed and I planned to pick it up next week. On Tuesday morning I
received a call from the shop telling me that there was 2" of jet a in
my
cockpit! Never happened before! Upon further investigation, they
found
that the aluminum belly tank vent line had been zip tied to the
braided
stainless hydraulic lines. running through the floor of my cabin. My
builder said that he would have never zip tied these 2 metals
together.
Since receiving the airworthiness certificate in 2006, my plane has
been
inspected by several different excellent lancair knowledgable
mechanics
including Lancair and noone has ever said anything about the aluminum
and
stainless lines being so close in proximity. As to who zip tied them
together and when-I don't know.
As evidenced by the attached photo electrolysis had occurred causing a
hole
in the aluminum vent tubing. The fuel from the wing tanks flowed into
the
belly tank then through the cracked aluminum vent tubing into my
cabin.
Fortunately this did not occur in flight as the pressurization would
have
probably pushed air into the belly tank and subsequently overboard
through
the wing vents! I would have had plenty of fuel but none in the belly
tank
feeding the engine thus unporting the engine.
I wonder if I would have recognized that in flight. Glad I didn't
find
out! But after thinking about it I have committed to my mind that if
the
belly tank seems to be emptying inexplicably, descend, turn off
pressurization and land!
The point of my post is just to make everyone aware of the obvious.
Avoid
putting different metals in close proximity or directly in contact
with
carbon fiber which can also cause electrolysis. We have changed most
of
our tubing to stainless but obviously not the belly tank vent-until
now!
As a neurosurgeon, we are always cognizant of making sure to avoid
using 2
different metal implants in proximity ie stainless steel and titanium(2
common metals
used in the spine) but this event really drove the point home!
Fly safely! %#*$ happens out there!
David Weinsweig
N750DW Propjet
weinsweigd@gmail.com
304-633-5221
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