Flying w/faulty gas gauge

"BTIZ" wrote in message
news:niBtb.3221$Ue4.826@fed1read01...
| I was once told.. that the Cessna type gauges only have to be accurate
when
| the tank is empty.. it should tell you so.. it does not need to be
accurate
| at a full or partially full tank..

You were told incorrectly, but you are in pretty good company. Even Rod
Machado made this error in one of his columns. He wrote back to me and told
me that he thought my interpretation of the regulations was probably more
correct. (But then, John King teaches the equal transit theory of lift, so
even "world famous" flight instructors like us get things wrong sometimes.
:-) Seriously, if you took all the faults and bits of misinformation taught
by just the top ten flight instructors in the country and put them into one
guy, you would probably have a really terrible flight instructor. But I
digress.)

The actual regulation states that the gauges must be calibrated so as to
read empty when usable fuel (as opposed to total fuel) is gone. Part 91
requires fuel gauges to indicate the quantity of fuel in each tank. I do not
believe that the momentary flickering caused by a bad sending unit in the
Cessna tanks seriously interferes with getting an accurate reading of the
amount of fuel in the tank. It is an annoyance at worst and you have to
watch it very closely to even see it.

Just how accurate a fuel gauge has to be to meet the requirements of Part 91
is not spelled out. I know of one guy (one of my instructors, actually -- I
was there) who was busted because his gauge read 2/3 full when it was
actually full. I know of at least one airplane that the gauge always reads
zero until you start the engine. I wonder how an inspector would feel about
that?

"BTIZ" wrote in message news:niBtb.3221$Ue4.826@fed1read01...
I was once told.. that the Cessna type gauges only have to be accurate when
the tank is empty.. it should tell you so.. it does not need to be accurate
at a full or partially full tank..

You were told wrong.

Would you fly this airplane?

Do you have enough gas to fly the airplane ? Yes. Is it legal ? No.
Does anyone know ? Yes. That's your biggest go/no-go problem at this
point.

Seriously, if this is your airplane, try wiggling the trim pot on the
back of the gauge and give it a shot of corrosion-X. Corrosion buildup
on the pot contact is common, resulting in jerky movement, indication
that comes back with tapping on glass, etc. That's not legal either,
BTW, so don't tell anyone you did it !

Would you fly this airplane?

No.

Remember that you should be flying the airplane for pleasure. If your fuel
gauge shows empty it is not fun to fly. Like the others have said it is
possible a fuel leak changed your calculations.

I wonder how many pilots on this newsgroup have run their airplane to where
they used ALL the useable fuel. Try it, it is NOT fun. I had it happen in
Mexico where fuel is not always available. I would rock the wings to check
movement in the fuel gauges. The last check I did minutes before landing
showed NO movement, dead. Luckily I landed, of course making a high approach
in case the engine quit. When I fueled the total gallons added was exactly
the useable amount of fuel. Never do that again....and never went back to
Mexico.

I understand that functional fuel gauges are required equipment for day VFR
flight.

That probably explains why the airport owner was mulling the
possibility of replacing the cork float in Zero Six Hotel.

The only gas gauge I trust is my watch. Two hours and it's time to
look for a nice smooth field.

all the best -- Dan Ford
email: (put CUB in subject line)

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

Cub Driver wrote:


I understand that functional fuel gauges are required equipment for day
VFR flight.

That probably explains why the airport owner was mulling the
possibility of replacing the cork float in Zero Six Hotel.

The only gas gauge I trust is my watch. Two hours and it's time to
look for a nice smooth field.

I agree on the trust part, the gauges in my 172 are notorious for their
inaccuracy. You didn't say whether or not you'd fly the plane but some will
interpret this as "go ahead and fly as long as you don't forget to wind
your watch".

I monitor the gauges more to catch an indication of a fuel leak rather than
for actual fuel consumption.


--
Frank....H

Yossarian wrote:
I understand that functional fuel gauges are required equipment for day VFR
flight. Yesterday during my preflight in a 172 I saw that the right gauge
was functioning intermittently--it would show full, flicker down to zero,
bounce around, etc. Tank was visually confirmed full. Mechanic messed
around with it for a while to no effect.

Would you fly this airplane?

Without even thinking about it.