Jim, fuel expands a lot as it is warmed. If you're full and the day gets hotter with the airplane sitting there, any fuel that spills out of the vents will run toward the cockpit....dangerous.
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15
Air Tractor 402 PT-6-20
EAA Flight Advisor/CFI/Tech Counselor
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!