If your fuel cap comes off in flight in your high wing Cessna you will
never be able to tell you are losing fuel by looking at your fuel gauge.
The problem is so bad that 182's have to have a placard stating that.
The problem is that the air flowing over the wing creates a suction
from the tank that makes the gauge read full.

C J Campbell wrote:

"Larryskydives" wrote in message
...

I would never trust a fuel guage. I was taught to alway visually check

and

know the aircrafts fuel usage.


You were taught a very popular myth. No doubt you were also taught the myth
(spread by Rod Machado and others) that your fuel gauge is only required to
be accurate when it reads zero fuel. The FAR require you to have a fuel
gauge that shows the quantity of fuel in each tank, whether you trust it or
not.

The reason you are to check the fuel in each tank is to see if your fuel
gauge is accurate. If it is not accurate, your airplane is not airworthy. I
think it is very strange for people to say that they do not trust a fuel
gauge, but they trust other, equally unreliable instruments such as the
ammeter, oil pressure and temperature, fuel flow, etc.

Your fuel gauge must be accurate, no matter how good you are at estimating
fuel flow and using your watch. Your fuel tank could leak, for example, or
your fuel cap could come loose during flight. The only way that you would
know that you are losing fuel would be from your fuel gauge, especially if
you fly a high wing airplane or you are flying at night. The fuel line from
one of your tanks could become blocked, creating an imbalance and
effectively cutting your fuel supply in half. One of the most common fuel
mismanagement accidents occurs when pilots switch to an empty tank. Your
fuel gauge is a critical item of fuel management, possibly the most
important one.