REFLECTOR:Low Fuel Light, my solution

reflector@tvbf.org reflector@tvbf.org
Sat, 26 Jul 2003 22:34:09 EDT


After my accident of June 1999, I installed the low fuel level float switch 
in my sump tank. I also was getting flashing low fuel level fuel light at 
various times such as left turn. First a fuel level sight tube was temporarily 
installed on my sump tank with a light shinning on it. This is easily done by 
adding tees at the sump tank fuel outlet and at the vent outlet. The sight tube 
showed that some sloshing of the fuel, and not low fuel was causing the flashing 
light. My solution was an adjustable time delay (from 1 sec to 10 sec) 
installed between the float switch and the light. I now have the time delay set at 6 
seconds and have not had a problem since. 
There is one condition where a vent is needed for the sump. More than once, 
Jean Prudhomme, during a long descent with relatively low fuel, has had a low 
sump fuel warning. He determined that the nose down attitude caused the fuel 
from the strake tanks to unport and stop flowing to the sump. He simply leveled 
out and light soon went out. He does have the large 90 gallon tanks. I believe 
this has also happened on the factory airplane. 
Finally I use and have the following warning on my panel " At least every 30 
minutes, check the fuel level in both wing tanks. IF an UNUSUAL IMBALANCE, is 
seen (5 to 10 gals) ASSUME FULLEST TANK IS UNUSABLE" This is a possible sign 
of a leaking fuel cap and fullest tank may not flow to sump. 
Don White   N19DW   XL/RG