REFLECTOR: fuel feed - my solutions

[Don19dw at aol.com]

As a result of my accident in June 1999, caused by a leaking fuel cap, I made 
the following changes. 
1) Added the sump tank "low fuel" warning system per Velocity plans, except 
located float slightly lower. The "low fuel" warning would have allowed we to 
reach an airport prior to fuel exhaustion from right tank and sump tank.and 
thus prevented the accident. 
However then during later flights, especially in turns would get flashing 
"low fuel" warnings which made me very nervous. To trouble shoot the problem I 
removed the rear seats and spar cover so I could visually see sump tank in 
flight. Using "T" fittings I added a vertical clear sight tube between top sump 
vent port and bottom outlet port plus a light shinning on the tube to see fuel 
level from my pilots seat. As Scott Swing suggested, the sloshing of the fuel in 
the sump tank was causing the flashing "low fuel" warning with little or no 
lowering of fuel level. 
2) In order to solve flashing "low fuel" warning, I added a time delay relay 
set at 6 seconds, before warning light went on, and have not had that problem 
since.
3) Installed a manual shut off valve in fuel line from each strake into sump 
tank. These left and right shut off valves are actuated by cables and small 
levers on each side of keel at pilots hip. These valves could be used in flight 
to isolate either strake tank from the sump if the fuel level in one side or 
the other is seen to be dangerously low. If the sump vent is closed, the fuel 
pump should "suck" fuel from the open fuel strake. However the argument for a 
closed sump vent is valid "to suck fuel" only if empty tank is shut off, 
otherwise air is "sucked" from the empty tank, rather than fuel sucked from the 
other tank. That apparently is what happened prior to my accident. So far have 
never used my added valves in flight. (However these valves are handy during 
servicing and I recommend  adding them for that reason alone)
4) Added an instrument panel note: " Warning: at least every 30 minutes, 
check fuel level in each strake tank. If an unusual balance is seen, ASSUME 
fullest tank is unusable"
5) After rebuilding the airplane, discovered the turn and bank indicator in 
the instrument panel, was not installed vertical, about 1/2 bubble off 
vertical. Once that was corrected, had to shim left rudder out 1/4 inch at trailing 
edge. Plane now flies perfectly level and straight and have not had any unusual 
fuel level problems since.
6) Finally check fuel caps are tightly closed and properly lubricated.

This may have been suggested to Jim already. During flight, have you held 
slight pressure on one rudder or the other, to see if fuel tank levels equalize? 
If that occurs, then I strongly suspect plane is not flying perfectly level 
and straight.
Don White   N19DW  XL/RG    
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