REFLECTOR: FUEL FEED & Vents
Scott Baker
sbakr at comcast.net
Thu Feb 17 00:26:36 CST 2005
Hello Keith,
Regarding your question:
>..." I have never been able to identify a situation in which the sump
> vent would do anything good for you (once the sump tank is filled the
> first
> time). Anyone got a scenario to the contrary?"
I have wondered about a low fuel, prolonged descent with the nose pitched
down situation where the mains could become "unported". If this were to
happen, and if the sump tank were not vented, then air from the displaced
fuel would be trapped inside the sump tank. A vented sump tank could easily
purge itself and refill with fuel when the aircraft reassumed a level flight
attitude.
The likelihood of unporting the fuel supply is not as rare as we might
think. My older model C210 for instance, was placarded to warn the pilot to
land with at least one-quarter (1/4) tank of fuel to avoid fuel starvation.
Cessna designers installed two small "saddle tanks" under the floor of the
C210A the following model year.
You pose a good question. It's good to get a lot of clear thinking heads to
help brainstorm ideas like this before deciding upon a design change -
especially to something as important as the fuel system. I donno. One
thing I've learned about aviation is - whatever the imagined unlikely
event - it's probably going to happen! Spins in a Grumman with the wrong
fuel tank selected = flameout. Point my 1960 C210 downhill with low fuel =
flameout. Many twins call for the selection of the "mains" for takeoff and
landing to avoid the possibility of fuel starvation.
Just thinking out loud.
SB
More information about the Reflector
mailing list