Arnold;
A143 has been down for awhile while I am developing an aluminum tank for it. I
got the leaks after draining gasoline from the tank. What happens is that the
tank expands and I am told that if it is drained it shrinks back slightly.
My crack developed right alonside one of the layup straps in the saddle area.
Get a small mechanics mirror and start probing around. The bulges you are
seeing
in the spar aperature are only an example of what happens to all of the
surfaces of the tank. When I cut my tank out of the cockpit seatback the top
of the tank was all rippled where it had expanded and was constrained by the
top of the seat back. The back flat surface also exhibited thesame phenomenon
it was just constrained by the cockpit section.
Steve Hagar
N40 SH
Mesa AZ
----- Original Message -----
From: Arnold Kr. Hansen
Sent: 4/29/2008 1:26:26 PM
Subject: Europa-List: Fuel tank - bulges and leakage.
Hi,
Shortly before start of taxiing, it was discovered that fuel was coming out of
the fuselage on my Europa XS trigear (LN-ABM), through the access holes below
the tank. Draining of the tank was started and the leakage stopped when 20 - 25
litres were remaining in the tank.
Two days before I had drained the tank completely since the aircraft had been
stationary
(in a heated hangar) since 1. july 2006 with app. 35 litres of mogas
in the tank. The day of start up I filled 18 litres and checked all hose
connections.
Started the engine and runned it for 5 minutes to check hose connections
to the recently installed oil thermostat. Then filled another 36 litres of
mogas and started the engine for the local flight.
Removing the wings, it was revealed that the tank front facing the wing spars,
had great bulges, bulges inwards and outwards, and the centre one touching the
aileron cross tube, see attached picture. I have not yet localized the crack,
but I suspect the saddle section just ahead of the fibreglass bracket. To me
the in and out shape of the bulges indicate compression stresses due to material
expansion (caused by the fuel applied, 95 octane mogas?). And I think the
crack is caused by shear stresses just forward of the bracket mentioned.
I will appreciate comments and advice. At present I do not trust the material,
polyethylene, used in the tank. Has anybody applied metal tanks?
Regards
Arnold Kr. Hansen
Europa XS trigear, Kit No.381
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