Switching Fuel Tanks
kei...@uiucdcs.cs.uiuc.edu
I am a student pilot (soloed) finishing the Private Pilot
certification at the University of Illinois. We fly Beechcraft Sports
here (BE-19-180) which have fuel selector knobs to switch tanks.
We've been taught that the most common cause of engine failure is fuel
starvation, and that this is most common when you forget to switch
tanks.
Why don't they make airplanes so that both fuel tanks supply fuel to
the engine at the same time? Seems like this would make things a lot
easier. You wouldn't forget to switch tanks, since you wouldn't have
to.
Any comments?
Gunnar Seaburg
c/o keifer@uiucdcs
Andrew Koenig
> the engine at the same time? Seems like this would make things a lot
> easier. You wouldn't forget to switch tanks, since you wouldn't have
> to.
They do. They're called Cessnas. It is apparently easier to go
without switching tanks in a high-wing airplane than a low-wing airplane.
The smaller Cessnas tend to have a fuel selector marked "L - Both - R - Off"
You still want to be able to use only one tank in case drawing
fuel unequally from the two tanks causes a weight unbalance during
extended cruising flight.
Ralph Keyser
> the engine at the same time? Seems like this would make things a lot
> easier. You wouldn't forget to switch tanks, since you wouldn't have
> to.
Cessna has heard your request. Dash over and check out the fuel system
on a Cessna single. They have a left-both-right-off selector, and most
of the time you just park it on both and leave it. The handbook suggests
selecting left or right during refueling, and you need to be able to
select a single tank for balancing if you get uneven fuel burn or if
you have contamination in one tank. The argument against this system
is that it fails to teach you anything about fuel management - a skill
needed in most twins and other complex aircraft. The statistics, however,
show that the simple Cessna fuel system leads to fewer fuel mismanagment
accidents than any other types of aircraft. Cessna pilots, alas, still
manage to run out of fuel, just like everyone else.
Ralph Keyser
Archer 8320C
Hughe...@xerox.com
They do make airplanes like this. Most of the ones I know about are
brand Cessna. Specifically the Cessna 150 and 152 which are good
trainers have a fuel on/off and that is it. Both tanks feed all the
time.
Bill
Hughe...@xerox.com
fuel unequally from the two tanks causes a weight unbalance during
extended cruising flight."
To avoid this you fly with the wings level. When you fail to do this
for a while you can tip the wings a bit (raise the one with the most
fuel) and the fuel will follow the old rule that a liquid seeks it's own
level. What you did not mention and to me is a stronger reason for
switchable tanks is what happens if you have lots of fuel but the engine
sputters or quits. It could be due to water in one tank. With the fuel
selector you can try the other one. Without the selector, you look for
a place to land real quick (you probably do this any time something
uncool happens--- if you are not always looking for a place to land just
in case, which is an excellent idea).
Bill
go...@pixar.uucp
>
> Why don't they make airplanes so that both fuel tanks supply fuel to
> the engine at the same time? Seems like this would make things a lot
> easier. You wouldn't forget to switch tanks, since you wouldn't have
> to.
>
I'm sure that Cessna pilots are going to mention the fact that many
high-wing planes do indeed have a "both" fuel selector position. This is
generally practicable only when using gravity to move the gas around. Low-
wing planes tend to have the off-left-right variety. Whatever you fly, make
darn sure you know which your plane has. Some high-wing planes do have an
"off" position. Some very short flights have resulted from fuel selector
confusion.
Checking that this selector moves, and is coupled to the knob, is
the *very first* item on the pre-flight I was taught. This is the result of
learning about an accident where a pilot was flying IFR, took off on one tank,
ran it near dry and then went to switch tanks. The selector knob sheared off
the shaft and he died in a fuel-starvation induced crash with a full tank of
fuel in one wing.
A very helpful technique I've found for remembering to switch tanks
is to watch the minute hand on the clock. If the hand is on the right side
of the dial, use the right tank. When it is on the left side, use the left
tank. This gets you a switch every 30 minutes which, in the Warrior at least,
is just peachy for keeping the weight balanced, etc.
--Craig
...ucbvax!pixar!good
Andrew Koenig
> Some very short flights have resulted from fuel selector confusion.
All airplanes have an "off" position.
Certification requires that it be possible to shut off all fuel
past the firewall in case of an engine fire.
Campb...@xerox.com
as the 152 or Skyhawk do have a both position. Gravity ensures a steady
flow of fuel. On a low wing airplane, which uses a fuel pum,p you have
to have a central header tank that both fuel tanks would feed into. The
engine would be driven by this tank which would always have fuel in it
even with the wings banked. But it costs more money and the header tank
takes up room and reduces the load of the airplane because of it's
weight. But it can be done. I know this for a fact because my Swift
does have a header tank and the fuel switch only says on or off, not
left, right and off.
Rick Campbell N3344K
Brent P. Callaghan
a good idea to select the fullest tank BEFORE you
do the pretakeoff runup. Switching tanks just before
takeoff is not a good idea.
--
Made in New Zealand --> Brent Callaghan
AT&T Information Systems, Lincroft, NJ
{ihnp4|mtuxo|pegasus}!poseidon!brent
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