Inop fuel gauge on rental + long XC

[Jim Logajan]

Nothing in the wording of 23.1337 states any required accuracy, validity or positive indication of the INDICATION "SYSTEM" except for (ref.) 23.959 which is the unusable fuel reg.

I can see no way to interpret your claim that doesn't make those two sentences in 23.1337 effectively null and void of useful meaning. All because the FAA failed to specify accuracy?

By the way, I believe you used the word "calibrated" as a synonym for "labeled", which are quite different concepts.

 

[wabower]

And you should also know that fuel can be leaking at a high rate if a pressurized line breaks in flight, and that nobody in the plane will be able to see it. When you're well into a X/C trip with :45 to destination and 2:00 of remaining fuel (according to plan) and lose an engine due to a dry tank, you'll understand how quickly it can happen. The good news is that it will clean the belly very nicely.

Thanks. You're right that I shouldn't have said, "ignore." We should use every tool and gauge in the cockpit, but understand how and why any of those elements might be wrong.

 

[PilotAlan]

The OP asked about an inop fuel gauge. answer: not airworthy per 91.205.

Then we went to how accurate the fuel gauges have to be. answer: it has to indicate 0 just before the motor expires. There is no required check by part 23,91 or 43. The needle just has to move.

I'm not sure where you get this when 91.205 clearly requires a "Fuel gauge indicating the quantity of fuel in each tank."

So heading half when full, or 3/4ths when half full is not a "indicating the quantity of fuel in each tank".

 

[ChrisK]

After reading this thread, I have decided that the fuel gauges are busted highly inaccurate in most of the aircraft I rent and I'm going to start paying more attention to them during preflight and on cross countries, and documenting what I see.

I might be in the market for another FBO shortly after they kick me out

 

[MAKG1]

I'm not sure where you get this when 91.205 clearly requires a "Fuel gauge indicating the quantity of fuel in each tank."

So heading half when full, or 3/4ths when half full is not a "indicating the quantity of fuel in each tank".

In the absence of an accuracy spec, it only means the labels have to exist. We might want it otherwise, but who decides if a 1/4 tank error is excessive, whereas a 0.1 gal error isn't? Subjective requirements for measurements are problematic.

 

[Jim Logajan]

In the absence of an accuracy spec, it only means the labels have to exist. We might want it otherwise, but who decides if a 1/4 tank error is excessive, whereas a 0.1 gal error isn't? Subjective requirements for measurements are problematic.

The FAA doesn't provide any quantifiable definition for "congested area" either, but that hasn't stopped it from successfully enforcing the regulation containing that phrase.

As to who gets to decide what is excessive error in any particular case - carried far enough, a judge. Otherwise the FAA. Everyone else has to try to anticipate what error would be seen as acceptable should something go wrong latter. The subjective nature of the regulation doesn't make it moot (though there are many regs where it would be nice if that was the case.)