Fuel Gauge Inop VFR Day

Hi George

Thanks for your replies :-)

Its true you learn something new everyday. I feel quite educated about
fuel gauges now!

Well, if you run out in a plane, you do exactly the same thing. Only the road is
a few thousand feet below you. :-)

My point exactly! If you've got somewhere safe to land.

It reminds me of a comedy sketch, I think it was Dave Allen, when he's
talking about emergency set downs, into the side of a mountain, or
looking at the in flight safety card and someone drawn shark fins in
the water right by the exits.

Many thanks

Hi Dan

The movement of the rheostat in the sender is linear but the
hinge's location creates a sine function to the indication, with the
top travel being rather slow and the lower travel moving much more
quickly.

I've notice something similar in cars, do you think this is cause by
the same thing?

So, why hasn't somebody invented a better way of checking fuel, or are
they about but just too expensive?

Regards

Ice blonde wrote:
Hi Dan


The movement of the rheostat in the sender is linear but the
hinge's location creates a sine function to the indication, with the
top travel being rather slow and the lower travel moving much more
quickly.


I've notice something similar in cars, do you think this is cause by
the same thing?

Yes, although I have seem some where the designer used a progressive
wind on the rheostat to linearize the output. However, this probably
costs 5 cents more per part so I've seen this only very rarely.

Matt

zatatime wrote:

Irrespective of the innop instrument, don't you always use time to
"guage" how much fuel you've burned?

Not always. A little dirt dauber managed to block both vents on my left tank
during a fuel stop coming back from Oshkosh. I draw from both during departure,
and switch to one tank or the other at the next 15 minute mark (eg. 1:00, 1:15,
1:30, or 1:45). After that, I switch tanks every half hour. It was well over 1.5
hours before it became apparent that the level in the left tank wasn't going
down at all, even when it was selected.

I landed and reamed the vents out before crossing the Appalachians. I also
topped off the right tank for good measure. If the gauges had been inop, I
probably would've gone down in eastern Pennsylvania.

My on-board tool kit paid for itself on that trip alone.

That stop was another testament to the great people you sometimes run into. The
FBO was closed, but the manager (who lives next door) trusted me to fill the
tank, fill out a credit card ticket, and leave it in the drop box.

George Patterson
Drink is the curse of the land. It makes you quarrel with your neighbor.
It makes you shoot at your landlord. And it makes you miss him.

That situation is easily fixed by using an L-shaped float wire.

The float on an L-shaped wire still has the same curved path
that it would with a straight wire. The better fix is an extended
sender that puts the hinge in the centre of the tank.
An even better fix would be two or three senders, wired
in series, at different places in the tank so that they would average
out the dihedral effects and so on. The capacitance-type senders are
often used this way in larger airplanes.
The best fix would be several capacitance senders feeding a
microprocessor that has been programmed for the tank's shape and
dihedral effect. The chip would drive the gauge. Probably been done,
somewhere.

Dan

Mike

Flew a 172 over to field where FAA Instructor was located to get my
Instructor Rating renewed after retiring. Don't tell me I should have
known what would happen. Wing tank guage went out on way over (15
minute flight).

FAA instructor grounded the aircraft because of bad guage and I had to
go get a ferry permit to get bird home to get repaired.

Way the system goes.

Big John, USAF Ret
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On 14 Oct 2005 18:03:21 GMT, wrote:

I have scheduled a plane for this weekend and reviewed the squak sheet. I
noted that the Fuel Gauge for one of the fuel tanks is Inop. I originally
thought this to be no big deal, but, upon further review of the FAR section
91.205, have found that it is a required peice of equipment for a day VFR
flight. Is my understanding of 91.205 correct? Without operative fuel
gauges for both tanks the plane is not air worthy?