Glastar Header Tank Leak

20 Jul 2005 Glastar Header Tank Leak

Header tank leak Gregory Allmann
This past weekend I had an experience that i felt I should pass on. I
have an Eggenfellner Subaru engine in my Glastar. I installed a 6
gallon header tank behind the seats to provide a common feed for both
wing tanks and a way to mix the return hot/hotter fuel form the fuel
injection system with the cooler gas coming from the wing tanks. This
also allowed for a very simple fuel system with no fuel management
issues. I have one on/off valve and that’s it. Works great. Header
tanks are not limited to Subaru engines or fuel injection and I think
others have header tanks with other engines. Now the bad part. I was
200 miles from home and at 3500 feet when I smelled gas. Looked out at
the wing tip vents to see if I was losing fuel and looked at the
trailing edge of the wings to see if I was losing fuel from a fuel cap.
Couldn’t see anything. Hit the ‘nearest’ button on my GPS and landed
without incident. Started looking around and found a split seam in my
header tank and it was spraying fuel all over the baggage compartment
floor. I have shut off valves for one wing tank, but not the other so
I had at least 15 gallons of fuel to contend with. I had a five gallon
fuel can with me and I attempted to drain one main tank and soak up the
spraying fuel with a rag. by the time I stopped the fuel spraying all
over I had at least a 1/2 inch of fuel in the bottom of the fuselage
under the seats and front floor boards. I spent hours cleaning up the
mess and thanked my lucky stars that I hadn’t been a fireball falling
out of the sky. What a potential for disaster. My brother drove 3 1/2
hours to pick me up and take my home and I left the plane at the
airport. I removed the tank and took it back to the weld shop that
welded it for me. He said that designing tanks is complicated and not
to be lightly considered. I designed my own. He said any light gage
tank that has any right angle welded corners are subject to fatigue
cracking form the flexing of the tank sides. This is exactly what
happened in my case. The point of my story is, if any of you have
header tanks, especially if self designed, you had better take note of
the possibility of fatigue cracking, fuel spillage in the cabin and the
potential for disaster. I am going to repair my tank, get my plane
home and design a new tank that eliminates (?) and/or severely reduces
the chance for fatigue cracking. I will post my new design and
reasoning for it shortly.