Inop fuel gauge - what would you do?

[denverpilot]

Diversions from plan do seem to garner special attention these days.

Has to be some DHS BS created by some bureaucrat run amok who also had the ability to change FAA policy.

(Note: That last part is important. FAA could have simply told them to step off.)

 

[PilotAlan]

See: http://forums.jetcareers.com/threads/say-reason-for-change-of-destination.129031/

And particularly "ATC RET 2003"'s suggested response....

ROFLMAO! I have GOT to remember that!

 

[ClimbnSink]

So people will stop filing flight plans and asking for atc services. Gotta love it.

Diversions from plan do seem to garner special attention these days.

Has to be some DHS BS created by some bureaucrat run amok who also had the ability to change FAA policy.

(Note: That last part is important. FAA could have simply told them to step off.)

 

[JohnPNW]

What about you? Would you have taken it? Am I being overly cautious? I don't think I am... the rules are there for a reason.

14 CFR 91.213 (a), (b), and (d) Inoperative instruments and equipment.
14 CFR 91.205 (a) (9)

You would be subject to violation for operating an unairworthy aircraft. The company might get a letter, but you might lose your license. Oh, and if there's a short someplace you might be dead.

You made the right (and also the correct) decision to decline to rent this unairworthy aircraft.

 

[Tom-D]

14 CFR 91.213 (a), (b), and (d) Inoperative instruments and equipment.
14 CFR 91.205 (a) (9)

You would be subject to violation for operating an unairworthy aircraft. The company might get a letter, but you might lose your license. Oh, and if there's a short someplace you might be dead.

You made the right (and also the correct) decision to decline to rent this unairworthy aircraft.

When the rules say the gauge is only required to be accurate when the tank is empty, do we have an airworthiness issue? = NO.

 

[Greg Bockelman]

When the rules say the gauge is only required to be accurate when the tank is empty, do we have an airworthiness issue? = NO.

You know, this gets thrown about on a regular basis. I would like to look that rule up for myself. Anyone able to quote chapter and verse on this? An actual reference so I can look it up?

 

[MassPilot]

A flight school I used to rent from before it went out of business had a DA-20 with an inop fuel gauge that they didn't bother to fix for a while. The CFI's there continued to take up students anyway, figuring they would just use the dipstick and estimate fuel burn. One day a CFI decided to take a student up on a lesson with 12 gallons in the tank (he didn't feel like taking the time to refuel) and figured it would be plenty for an hour or so flight in a plane that burns 6 gallons per hour. During the lesson the engine began sputtering as they were maneuvering around, but then returned to normal. They were heading back to the airport when the engine sputtered again and then quit. The CFI was unable to restore engine power, but luckily managed to deadstick it onto the runway. On the ground they discovered the fuel tank was completely dry. It turns out the plane had just come back from maintenance (where they still didn't bother to fix the fuel gauge) and the mixture control wasn't rigged properly, resulting in excess fuel burn.

 

[bradg33]

You know, this gets thrown about on a regular basis. I would like to look that rule up for myself. Anyone able to quote chapter and verse on this? An actual reference so I can look it up?

There is no "chapter and verse" on this because it is NOT the rule. The gauges have to be accurate, period. Most in service aren't particularly accurate, but that doesn't change the actual certification rules under both CAR 3 and Part 23. Those who think the rule is that they only have to be accurate at zero are simply incorrect. It's usually due to either (1) lack of reading comprehension skills, or (2) "I heard it from another guy...".

 

[Everskyward]

Fast forward to today, 2 months later.

Fast forward to today, five years later. How's the fuel gauge doing?

 

[Capt. Geoffrey Thorpe]

You know, this gets thrown about on a regular basis. I would like to look that rule up for myself. Anyone able to quote chapter and verse on this? An actual reference so I can look it up?

Indicating zero at zero usable fuel is a necessary, but not sufficient condition.

23.1337
(b) "Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:

(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);+

See also:

91.205
"General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition
...
Fuel gauge indicating the quantity of fuel in each tank."

 

[bradg33]

Indicating zero at zero usable fuel is a necessary, but not sufficient condition.

23.1337
(b) "Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:

(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);+

See also:

91.205
"General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition
...
Fuel gauge indicating the quantity of fuel in each tank."

Bear in mind that many of the planes we fly are not certified under Part 23, but under CAR 3 (older rules). On this point, CAR 3 provides:

"§ 3.672 Fuel quantity indicator. Means shall be provided to indicate to the flight personnel the quantity of fuel in each tank during flight. Tanks, the outlets and air spaces of which are interconnected, may be considered as one tank and need not be provided with separate indicators. Exposed sight gauges shall be so installed and guarded as to preclude the possibility of breakage or damage. Fuel quantity indicators shall be calibrated to read zero during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply as defined by § 3.437."

 

[Tom-D]

You know, this gets thrown about on a regular basis. I would like to look that rule up for myself. Anyone able to quote chapter and verse on this? An actual reference so I can look it up?

23.1337
(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:

(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

23.1553-55
(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

§23.959 Unusable fuel supply.
(a) The unusable fuel supply for each tank must be established as not less than that quantity at which the first evidence of malfunctioning occurs under the most adverse fuel feed condition occurring under each intended operation and flight maneuver involving that tank. Fuel system component failures need not be considered.

(b) The effect on the usable fuel quantity as a result of a failure of any pump shall be determined.

 

[Tom-D]

There is no "chapter and verse" on this because it is NOT the rule. The gauges have to be accurate, period. Most in service aren't particularly accurate, but that doesn't change the actual certification rules under both CAR 3 and Part 23. Those who think the rule is that they only have to be accurate at zero are simply incorrect. It's usually due to either (1) lack of reading comprehension skills, or (2) "I heard it from another guy...".

wrong 23.1553-55 read it.

 

[Tom-D]

X/AB is the exception to the rule

 

[Greg Bockelman]

What I see in the regulation is a requirement that it read Zero when there is no more usable fuel in the tank as determined by the manufacturer.

What I do NOT see is where it says that it is the ONLY time it must be accurate.

Therefore, I conclude that the interpretation that it is the ONLY time the gauge be accurate is a misinterpretation of the rules.

Of course that is my opinion. Others may disagree.

 

[bradg33]

wrong 23.1553-55 read it.

Those two sections of the regs don't support your position. That said, I've found that most people who believe the whole "only accurate at zero" myth don't care that it's a myth and don't want to be corrected.

 

[bradg33]

What I see in the regulation is a requirement that it read Zero when there is no more usable fuel in the tank as determined by the manufacturer.

What I do NOT see is where it says that it is the ONLY time it must be accurate.

Therefore, I conclude that the interpretation that it is the ONLY time the gauge be accurate is a misinterpretation of the rules.

Of course that is my opinion. Others may disagree.

Your opinion, and interpretation, is the legally correct one and the common sense one. Why would the FAA require a fuel gauge in the airplane, but not care whether it's actually accurate? Under the "other" interpretation, you could have .5 gallons of usable fuel in the airplane, and it's totally OK if the gauge reads "full," so long as the gauge immediately goes to "zero" when that .5 gallons is burned. That's just asinine.

 

[MassPilot]

Is there any requirements for how accurate the fuel gauges need to be? Cessna fuel gauges, for example, are notoriously inaccurate.

 

[Checkout_my_Six]

Is there any requirements for how accurate the fuel gauges need to be? Cessna fuel gauges, for example, are notoriously inaccurate.

Only when empty and at level flight.

 

[Tom-D]

What I see in the regulation is a requirement that it read Zero when there is no more usable fuel in the tank as determined by the manufacturer.

What I do NOT see is where it says that it is the ONLY time it must be accurate.

Therefore, I conclude that the interpretation that it is the ONLY time the gauge be accurate is a misinterpretation of the rules.

Of course that is my opinion. Others may disagree.

If there were any more requirements they would be listed.
also there are no requirements other than navigation instruments to be calibrated in service.

 

[Tom-D]

Those two sections of the regs don't support your position. That said, I've found that most people who believe the whole "only accurate at zero" myth don't care that it's a myth and don't want to be corrected.

If you don't believe the regulations there isn't much to say.

 

[Tom-D]

Your opinion, and interpretation, is the legally correct one and the common sense one. Why would the FAA require a fuel gauge in the airplane, but not care whether it's actually accurate?

That is exactly what they did, simply because there is no requirement to calibrate any gauge in service.

 

[bradg33]

Is there any requirements for how accurate the fuel gauges need to be? Cessna fuel gauges, for example, are notoriously inaccurate.

They're notoriously inaccurate because owners/operators are too cheap to spend the time/money to keep them working properly.

 

[flyingron]

There is no "chapter and verse" on this because it is NOT the rule. The gauges have to be accurate, period. Most in service aren't particularly accurate, but that doesn't change the actual certification rules under both CAR 3 and Part 23. Those who think the rule is that they only have to be accurate at zero are simply incorrect. It's usually due to either (1) lack of reading comprehension skills, or (2) "I heard it from another guy...".

Actually, the rules say nothing about ACCURACY of fuel gauges period (either CAR3 or FAR23).

All it says is that the E mark corresponds to zero USABLE fuel (as opposed to say, bone dry)

 

[MauleSkinner]

Actually, the rules say nothing about ACCURACY of fuel gauges period (either CAR3 or FAR23).

All it says is that the E mark corresponds to zero USABLE fuel (as opposed to say, bone dry)

So is that lack of reading comprehension skills or did you hear that from some other guy on the Internet, Ed?

23.1337:

(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:

(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

If it actually indicates usable fuel quantity, it's accurate. It can't be anything else.

 

[bradg33]

Actually, the rules say nothing about ACCURACY of fuel gauges period (either CAR3 or FAR23).

All it says is that the E mark corresponds to zero USABLE fuel (as opposed to say, bone dry)

You don't believe that the rule(s) that require:

"Means shall be provided to indicate to the flight personnel the quantity of fuel in each tank during flight." (CAR 3)

-and-

"There must be a means to indicate to the flight crew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used." (Part 23)

require that the gauges be accurate? So your position is that an inaccurate gauge can somehow indicate to the crew the "quantity of usable fuel in each tank during flight"? Why require an indicator calibrated in appropriate units and marked if accuracy isn't required? When the FAA says the gauge must indicate the "quantity of usable fuel in each tank," you believe it also needed to explicitly say "that gauge must be accurate..." and that the failure to do so means the gauge does not have to be accurate? See how absurd that is?

 

[Matthew]

What I see in the regulation is a requirement that it read Zero when there is no more usable fuel in the tank as determined by the manufacturer.

What I do NOT see is where it says that it is the ONLY time it must be accurate.

Therefore, I conclude that the interpretation that it is the ONLY time the gauge be accurate is a misinterpretation of the rules.

Of course that is my opinion. Others may disagree.

That's the same way I read it. If this snippet from a previous post is correct and applicable for a C172:

>>>
23.1337
(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used. In addition:
<<<

It does say "calibrated in appropriate units", so you might assume that when there are tick marks at 5/10/15 gallons or whatever unit is used, that the spacing between those tick marks actually means something. It doesn't say how accurate those marks need to be, though. Can they be off by +/- 5%? 25%?

>>>
(1) Each fuel quantity indicator must be calibrated to read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);
<<<

Calibrated so that zero means no more usable. And there is no tolerance given on that, either. But it's put there so that if the gauge has an error in it across full scale that the error is minimized on the EMPTY side.

Just my guess, but whoever designed the systems for reading and displaying fuel levels probably put a little time and effort into creating something that was more useful than showing EMPTY with no usable, and FULL with > no usable.


edit: I'm not an owner -- are the fuel guages tested or re-zeroed at annual or on some other schedule?

 

[flyingron]

As I stated the regs say NOTHING about accuracy. You can read that they imply such, but if there was a requirement for accuracy there'd be an indication as to what that is in
percent or PPM, or something. For example, compass accuracy is stated to be ten degrees. VOR accuracy to a different number of degrees.

All it says is that the 0 mark is zero usable. It says nothing (and you're inventing) things to think that the it's somehow a percentage error of overall system error or anything else. It just says that's what 0 means.

 

[bnt83]

As I stated the regs say NOTHING about accuracy. You can read that they imply such, but if there was a requirement for accuracy there'd be an indication as to what that is in percent or PPM, or something. For example, compass accuracy is stated to be ten degrees. VOR accuracy to a different number of degrees.

Pretty sure that most regulations that seem vague or poorly written were done so intentionally.

 

[oilburner]

I'll occasionaly get a big red X on a fuel gauge upon initial boot up of the g1000.
Usually always fixed by turning avionics switch on/off and letting it boot again.

Those calibrated dip tubes for physically measuring fuel supply at preflight are so cheap to obtain. Anyone using either glass or steam fuel gauges would be a fool for not using them on any aircraft they're checked out in.

 

[Tom-D]

edit: I'm not an owner -- are the fuel guages tested or re-zeroed at annual or on some other schedule?

NO. the minimum is FAR 43-D. as to what is inspected as an annual. As an A&P-IA we can add to that list.
When we do add requirements we should be able to rationalize the addition.

 

[MauleSkinner]

As I stated the regs say NOTHING about accuracy. You can read that they imply such, but if there was a requirement for accuracy there'd be an indication as to what that is in
percent or PPM, or something. For example, compass accuracy is stated to be ten degrees. VOR accuracy to a different number of degrees.

All it says is that the 0 mark is zero usable. It says nothing (and you're inventing) things to think that the it's somehow a percentage error of overall system error or anything else. It just says that's what 0 means.

Ok...so what term would you use to say that In level flight I can always tell when I have, say, 15 gallons in the tank? That's not implying, the reg says I have to be able to determine my usable fuel in level flight.

 

[flyingron]

The regs say you have to have gauges that are marked in some units and that 0 is set to the end of usable fuel. As I've stated and nobody has refuted, there's no statement about how accurate they have to be. The FARs simply don't place an accuracy requirement on the gauges (and most are horrendously inaccurate for a number of reasons not the least of which is that it's hard to maintain a consistent level in a shallow pan that this a wing tank). There are lots of places where the FAA puts an accuracy requirement on things, but this isn't one of them. My altimeter has accuracy requirements. My compass has accuracy requirements. Certain airspeeds have accuracy requirements. Fuel gauges do not.

I stand by my original statement. It's not that the FAA says that the fuel gauges are only accurate at empty, the FAA doesn't say their accurate at all.

 

[Greg Bockelman]

What does the word "calibrated" in this context mean?

 

[MauleSkinner]

Ron is simply saying that the FAA requires pilots to fly only when there is no usable fuel remaining in the tanks. It's actually illegal to fly with more than that.

 

[luvflyin]

Inop fuel gauge - what would you do?

Cover it with duct tape. Cover operating fuel gauges with duct tape also. Now, practice fuel management.

 

[Tom-D]

What does the word "calibrated" in this context mean?

It has been verified correct.

 

[flyingron]

Ron is saying the FAA doesn't put any specific requirements for accuracy on fuel gauges. You can say all you want, but it doesn't change that.
If there was an accuracy requirement, it would be stated. Stating that you have to set the gauge so 0 is end of usable fuel is not an accuracy statement. Saying it is "calibrated" by itself is not an accuracy requirement. It's like saying the wheels on your aircraft must be round. Fine, but to what degree? Is a little flat OK.

You'll not find anything. Not in the FARs, not in an AC, not in an FAA order that says anything about fuel gauge accuracy. On the other hand, look at compasses. Part 23 and 25 tell you how accurate they need to be. Altimeters (at least for IFR) have very definite accuracy requirements.

 

[bradg33]

Ron is saying the FAA doesn't put any specific requirements for accuracy on fuel gauges. You can say all you want, but it doesn't change that.
If there was an accuracy requirement, it would be stated. Stating that you have to set the gauge so 0 is end of usable fuel is not an accuracy statement. Saying it is "calibrated" by itself is not an accuracy requirement. It's like saying the wheels on your aircraft must be round. Fine, but to what degree? Is a little flat OK.

You'll not find anything. Not in the FARs, not in an AC, not in an FAA order that says anything about fuel gauge accuracy. On the other hand, look at compasses. Part 23 and 25 tell you how accurate they need to be. Altimeters (at least for IFR) have very definite accuracy requirements.

This really is just a completely absurd position. The fact that some people truly believe that required fuel gauges don't have to be accurate just blows my mind, and if it ever really comes down to it, I suspect the FAA will take the position that of course they have to be accurate. You reference other instruments with defined "Accuracy" requirements, but that's really a misnomer. Those instruments don't have "accuracy" requirements, they have a defined range of acceptable error (some percentage, number of feet, etc.). The regulations regarding fuel gauges do NOT have a published range of acceptable error, meaning that under a literal reading, they must be perfectly accurate as the FAA has not defined an acceptable range of error. The failure to define an acceptable range of error does not, using common sense (which I know many prefer to abandon here), mean that the acceptable range of error is 99%, so long as it reads zero when there's no usable fuel left.

 

[Matthew]

I haven't worked with a metrology department for a long, long time. But back in the day, if there were no tolerances given, we assumed a couple things: 1) whoever wrote the specs forgot something, 2) since no error range was given, we had to assume that none was allowed (and we couldn't do that kind of measurement because all measurements will have some error). We would not assume that since no tolerance was given that ALL error was allowed.

FAA wrote it this way on purpose - but I am not sure of that purpose.