Inop fuel gauge - what would you do?

[skidoo]

Another sweet feature on the G1000 fuel system is the range ring. Once, after filling up at a destination, I forgot to re-set the totalizer. So, even though I had plenty of fuel, on the return flight, the totalizer thought I had just a little left. A ring appeared on the moving map which did not make it to my home base. As I got closer to home base, that ring got smaller, and then I think I even got an alert to low fuel. I let the totalizer go that way to see how it worked. Again, I knew I started with plenty and the regular fuel gauges confirmed that.

 

[BellyUpFish]

I've never had a G1000 equipped plane give me red X's on the ground. Always happened in the air.

Fuel gauges are the most inaccurate gauges in the plane, as far as I'm concerned.

 

[Kelvin]

Which fuel stick do you use?

Troy, I know you didn't ask me but I use a Fuelhawk....calibrated for the 182..

 

[wabower]

Many. if you're flying them, you will know pretty quick.

Such as?

If you calibrate the stick yourself and always insert it the same way, it should be very accurate regardless of the geometry of the tank with a few excpetions - for example some tanks where the filler neck is on the outboard side may not be able to indicate lower levels, but then you probably shouldn't be taking off with the fuel that low in the first place.

The only other issue that I can think of would be bladder tanks if there have been wrinkles and the fuel capacity has been reduced to less than advertised.

 

[Fearless Tower]

Many. if you're flying them, you will know pretty quick.

I suppose you must have 'top men' flying them?

 

[wabower]

What the hell is that?

I suppose you must have 'top men' flying them?

 

[bbchien]

I'm afraid that's an old wive's tale (or old pilot's tale).


That reg is controlling for all aircraft, and the gauge MUST indicate the quantity remaining. There's no specific guidance for CAR3 aircraft in accuracy. TSO-C55 is not mandatory for general-aviation aircraft, but we can use it to get a ballpark idea. TSO-C55 specifies a tolerance of 3% of full scale.

The 172SP is certified under Part 23, which has a further (higher) requirement that the 'zero' indication must equal when *usable* fuel has been exhausted.
The only difference between the two is that a CAR3 plane may show unusable fuel in the total remaining, a FAR23 plane may not.

Regardless, FAR91.205 is binding on all pilots of standard category aircraft, and clearly requires an accurate fuel gauge.

It's completely not clear to me that your citation and all the verbiage for two pages around it, specifies the accuracy points for the "indicating fuel quantity".

Think about it, if 91.205 was interpreted as being accurate over the whole span, the entire CAR 3 fleet would be unable to be operated even though the aircraft are legal themselves. This is clearly not true..

 

[PilotAlan]

It's completely not clear to me that your citation and all the verbiage for two pages around it, specifies the accuracy points for the "indicating fuel quantity".

Think about it, if 91.205 was interpreted as being accurate over the whole span, the entire CAR 3 fleet would be unable to be operated even though the aircraft are legal themselves. This is clearly not true..

Hi Bruce. Thanks for the question.
To be clear, I was saying that the fuel gauges have to work in accordance with their type design.

No one would argue that a tach that was only correct when the engine was off, or a manifold pressure gauge that was only correct at full power, or landing gear lights that were only correct when the gear was down would meet airworthiness requirements.
But somehow, fuel gauges are 'optional', and improperly functioning gauges are perfectly OK.

There are only nine required instruments for day VFR, but the most common cause of accidents is fuel exhaustion and I think our cavalier attitude toward them is part of the problem.
FBOs that don't want to pay to take the time and work to keep the gauges working have spread this idea that "they only have to right when they're empty", or that's it no big deal if they're inop.

I admit to having gotten caught up in that BS when I was a renter. After buying a plane and learning the regs (and being responsible for the aircraft), I have a much different attitude.

 

[Tom-D]

Hi Bruce. Thanks for the question.
To be clear, I was saying that the fuel gauges have to work in accordance with their type design.

No one would argue that a tach that was only correct when the engine was off, or a manifold pressure gauge that was only correct at full power, or landing gear lights that were only correct when the gear was down would meet airworthiness requirements.
But somehow, fuel gauges are 'optional', and improperly functioning gauges are perfectly OK.

There are only nine required instruments for day VFR, but the most common cause of accidents is fuel exhaustion and I think our cavalier attitude toward them is part of the problem.
FBOs that don't want to pay to take the time and work to keep the gauges working have spread this idea that "they only have to right when they're empty", or that's it no big deal if they're inop.

I admit to having gotten caught up in that BS when I was a renter. After buying a plane and learning the regs (and being responsible for the aircraft), I have a much different attitude.

READ
FAR 23.1337 and 23.1553

 

[PilotAlan]

READ
FAR 23.1337 and 23.1553

Thank you Tom. I am very familiar with them.
As I said, FAR Part 23 requires that unusable fuel not be included in the fuel quantity indication. It doe NOT state that the gauge only has to accurate at zero.
And it only applies to Part 23 aircraft, not to vast majority of the aircraft out there which were certified under CAR 3.

That is NOT the same as "only having to accurate at zero". By your logic, an inop fuel indicator stuck at zero would be airworthy, as it would be correct when the tank is empty.

So again, please cite the authority for your statement that the gauge only has to accurate when empty (a tank with 5 gallons on unusable fuel remaining is not empty).

 

[Fearless Tower]

What the hell is that?

Never seen Raiders of the Lost Ark? Your 'many' comment was akin to the 'top men' line.

Obtuse and non-committal.

 

[poadeleted20]

Just be careful with that FuelHawk -- the guys at the local flight school had to fish one out of the tank of their 152 last week. The scary part is all the other junk they found in there in the process.

 

[Dan Thomas]

I read FAR 91.205 and see this:
"§ 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

(a) 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.
(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:
<bunch of stuff snipped>
(9) Fuel gauge indicating the quantity of fuel in each tank.
Etc."


The fuel gauge must indicate the fuel in each tank, which it could not do if it was dead, and anyway the first paragraph stipulates that the instruments listed be "in operable condition."


For night and IFR ops, the regs include these instruments as well. I don't see anything here that would permit a pilot to depart with a dead gauge.


In Canada, our wording is a bit different but the intent is the same:


605.14 No person shall conduct a take-off in a power-driven aircraft for the purpose of day VFR flight unless it is equipped with
<snip>
(j) a means for the flight crew, when seated at the flight controls to determine
(i) the fuel quantity in each main fuel tank...



So a dipstick does not qualify, and a dead gauge would not provide the means to determine the fuel quantity.


Dan

 

[wabower]

OK, start with King Airs. When you're done looking through the list of those, there are many more.

Never seen Raiders of the Lost Ark? Your 'many' comment was akin to the 'top men' line.

Obtuse and non-committal.

 

[Tom-D]

Thank you Tom. I am very familiar with them.
As I said, FAR Part 23 requires that unusable fuel not be included in the fuel quantity indication. It doe NOT state that the gauge only has to accurate at zero.
And it only applies to Part 23 aircraft, not to vast majority of the aircraft out there which were certified under CAR 3.
Check your type certificate before you make a statement like that, the 172 all were on the same type certificate issued under CAR requirements. many are still in service.
That is NOT the same as "only having to accurate at zero". By your logic, an inop fuel indicator stuck at zero would be airworthy, as it would be correct when the tank is empty.

So again, please cite the authority for your statement that the gauge only has to accurate when empty (a tank with 5 gallons on unusable fuel remaining is not empty).

They are only calibrated at "0" that is the only place that they are required to be accurate, they must work, but are not required to be accurate at any other point. All instruments in the aircraft must work or be placarded inop. but there is no requirement for calibration on any except the ailtemeter and VOR heads in IFR ops.

So, if you believe the fuel gauge must be accurate at all levels show me the requirement to calibrate while in service.

 

[AEROBAT]

The only time I believe Cessna fuel gauges is when they read low or empty. I havn't rented in years but if the same plane had a problem with it's fuel gauge after a pilot had snagged it previously I would wonder about their maintenance.

 

[Tom-D]

I read FAR 91.205 and see this:
"§ 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

(a) 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.
(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:
<bunch of stuff snipped>
(9) Fuel gauge indicating the quantity of fuel in each tank.
Etc."


The fuel gauge must indicate the fuel in each tank, which it could not do if it was dead, and anyway the first paragraph stipulates that the instruments listed be "in operable condition."


For night and IFR ops, the regs include these instruments as well. I don't see anything here that would permit a pilot to depart with a dead gauge.


In Canada, our wording is a bit different but the intent is the same:


605.14 No person shall conduct a take-off in a power-driven aircraft for the purpose of day VFR flight unless it is equipped with
<snip>
(j) a means for the flight crew, when seated at the flight controls to determine
(i) the fuel quantity in each main fuel tank...



So a dipstick does not qualify, and a dead gauge would not provide the means to determine the fuel quantity.


Dan

Do you know why both countries require that certification requirement?





tanks leak in flight.



and those who dip and fly, not knowing the fuel has left the aircraft will be in the weeds long before they get to the destination.

 

[PilotAlan]

Check your type certificate before you make a statement like that, the 172 all were on the same type certificate issued under CAR requirements. many are still in service.

Actually, the 172 in question was recertified under Part 23 when Cessna restarted production with the 172R and 172S.
If you look at the TCDS, it specifies Part 23 as the certification basis for the 172R and S.
Previous models (through the 172Q) are certified under CAR 3.

Under TCDS 3A12:
172R and 172S

XI - Model 172R, Skyhawk, 4 PCLM (Normal Category), 2 PCLM (Utility Category), Approved June 21, 1996
...
Certification Basis: Part 23 of the Federal Aviation Regulations

XII - Model 172S, Skyhawk SP, 4 PCLM (Normal Category), 2 PCLM (Utility Category), Approved May 1, 1998
...
Certification Basis: Part 23 of the Federal Aviation Regulations

 

[Tom-D]

Actually, the 172 in question was recertified under Part 23 when Cessna restarted production with the 172R and 172S.

Under TCDS 3A12:
172R and 172S

The reference I showed above is 23 requirements.

but the R&S are a lesser part of the production run. 1956-1981 account for the most of the 27,000 built on 3A12, and all aircraft were built on that type certificate it is now at revision 81, the R&S were built on the new production certification as new models which used the Part 23 rules.

there are three types of fuel indication systems used in the Cessna 100 series. the early one have a Clark style, mid range were resistance type, and the R&S are capacitive type. none of which has a inservice calibration requirement. other than indicating empty when the tank is.

a stuck gauge is not an operable one, and needs to be repaired.

the big RED X is not operating, and not legal to fly.

 

[denverpilot]

Just be careful with that FuelHawk -- the guys at the local flight school had to fish one out of the tank of their 152 last week. The scary part is all the other junk they found in there in the process.

Ron's saying, "Hang on to your stick!"

Or is that, think with your dipstick!

 

[denverpilot]

and those who dip and fly, not knowing the fuel has left the aircraft will be in the weeds long before they get to the destination.

No one who said we stick said anything about not checking the gauge during pre-flight nor did we say we don't monitor the inaccurate bouncy little cusses IN-flight.

Don't try to drag us into your goofy argument.

Plus doesn't that make Alan's point anyway?

I'll also take a moment to re-clarify that my beef is with Cessna gauges.

I liked Tony's "what fuel gauges" comment from my soaring days, and the Husky was good. The Mooney was ok but I still didn't trust it 100%. Back then I didn't have a stick. I just topped the thing off all the time out of self-preservation paranoia.

And the ATR-42... Well, I can't say I even looked since I was too busy gawking at the gadgets starry-eyed and trying to hold something resembling the assigned altitude of FL230 for 1/2 an hour or so.

But Cessnas... They're mostly junk. Maybe the ones in the T182T G1000 Nav III are good but I have exactly 0.5 of taxi time in that variety of C182. Flight scrubbed after a very long and detailed first-flight checkout with tons of explaining the panel to my dumb ass while idling and a run-up, and then the wind kicked up to over 20 knots, most of it crosswind, and stayed there for no known reason that afternoon for an hour or so. So we looked at each other, shrugged, and put the airplane away for the day.

 

[Tom-D]

No one who said we stick said anything about not checking the gauge during pre-flight nor did we say we don't monitor the inaccurate bouncy little cusses IN-flight.

I read that some were flying gauges that didn't work. stuck needles and all.

Don't try to drag us into your goofy argument.

No argument, simply pointing out that both Canada and the US have the same rule for the same reason

Plus doesn't that make Alan's point anyway?

sorta, Alan has a valid point, the gauges should work and the reading should be accurate. But the is no requirement for that.

I'll also take a moment to re-clarify that my beef is with Cessna gauges.

I liked Tony's "what fuel gauges" comment from my soaring days, and the Husky was good. The Mooney was ok but I still didn't trust it 100%. Back then I didn't have a stick. I just topped the thing off all the time out of self-preservation paranoia.

And the ATR-42... Well, I can't say I even looked since I was too busy gawking at the gadgets starry-eyed and trying to hold something resembling the assigned altitude of FL230 for 1/2 an hour or so.

But Cessnas... They're mostly junk. Maybe the ones in the T182T G1000 Nav III are good but I have exactly 0.5 of taxi time in that variety of C182. Flight scrubbed after a very long and detailed first-flight checkout with tons of explaining the panel to my dumb ass while idling and a run-up, and then the wind kicked up to over 20 knots, most of it crosswind, and stayed there for no known reason that afternoon for an hour or so. So we looked at each other, shrugged, and put the airplane away for the day.

Cessna resistance fuel gauges can be made to read correctly, simply clean all connections at annual and reduce the variance in the circuit which effects the reading on the gauge.

and remember it is the owner operator's responsibility to get discrepancies repaired.

there is a very simple method of knowing which type of system you have in your cessna. If you must look at the wing butt to see the gauge you have the clark style, if the gauge is in the instrument panel, its a resistance type, If the gauge is in a glass dash, it is capacitive.

Fuel quantity systems are very good indicator of owner's attitude for maintenance, If they maintain that system they will maintain all systems.

 

[Dan Thomas]

there are three types of fuel indication systems used in the Cessna 100 series. the early one have a Clark style, mid range were resistance type, and the R&S are capacitive type.

We have a 172S with G100 glass. It has the potentiometer senders. Having glass is no guarantee of capacitance senders.

Dan

 

[Skylane81E]

We have an R with out glass, resistance type senders. Just as much junk as our 77 N model. I will give the new plane credit though, the sender I replaced still was as accurate as any cessna, but it leaked past the terminal stud.

 

[Tom-D]

We have an R with out glass, resistance type senders. Just as much junk as our 77 N model. I will give the new plane credit though, the sender I replaced still was as accurate as any cessna, but it leaked past the terminal stud.

The only one I have dealt with was a S it had the rod cap. type.

My F-24 has been up dated to the Cap type, with OEM S&W gauges. works great.

 

[denverpilot]

Tom, our fuel system and sensors are good on the aircraft I own today. If they weren't, we'd fix 'em.

Good info on the MX though. We just had a bladder replaced last year on one side too. Plenty of expensive but worth it eyeballs on fuel related "stuff" lately.

My comments were mainly from all my time in the rental fleet prior to our nice bird. There's no end to owners with leasebacks who don't bother fixing anything right, in the rental fleet. I've flown some seriously junky stuff. Budget dictated it, mostly.

I knew I was over rentals when one CFI confided that an unnamed local FBO would charge the CFI for the shop time on an intermittent that couldn't be found if it were squawked during a dual flight.

Great safety culture builder there. I learned why no one ever seemed to squawk any of the minor but annoying broken stuff in their birds.

I hope they've stopped that policy. Talk about heads up and locked...

 

[Tom-D]

Tom, our fuel system and sensors are good on the aircraft I own today. If they weren't, we'd fix 'em.

Good info on the MX though. We just had a bladder replaced last year on one side too. Plenty of expensive but worth it eyeballs on fuel related "stuff" lately.

My comments were mainly from all my time in the rental fleet prior to our nice bird. There's no end to owners with leasebacks who don't bother fixing anything right, in the rental fleet. I've flown some seriously junky stuff. Budget dictated it, mostly.

I knew I was over rentals when one CFI confided that an unnamed local FBO would charge the CFI for the shop time on an intermittent that couldn't be found if it were squawked during a dual flight.

Great safety culture builder there. I learned why no one ever seemed to squawk any of the minor but annoying broken stuff in their birds.

I hope they've stopped that policy. Talk about heads up and locked...

Once upon a time in a FBO in a far away land, there was an unscrupulous operator that had 6 aircraft on lease back. He never fixed any thing for about 2 years, the IA he had on staff pencil whipped the 100 hours and annuals.

The renters thought they would force the FBO to repair the aircraft, they banded together an flew the aircraft to other fields and called the FBO to say they would not fly the aircraft again until the discrepancies were repaired.
The FBO operator simply said "OK thanks for the call"
the pilots/renters waited all day for some one to show up to fix the aircraft, no one did.
The FBO operator simply packed up his stuff from the hangar, turned the hangar back to the Port and went home with all the cash.
The aircraft owners were required to go get their aircraft have them fixed and all the renters were with out aircraft.
As far as I know the mess is still in court. lesson? all you can do is rent or not. vote with your bucks.

 

[Skylane81E]

I can understand it, we often can only afford to pick pretty or safe when it comes to the planes. We always pick safe but I can understand the reason for choosing pretty, pretty rents.

And if you are on a smaller budget than we are then you might not be able to do all the safety items either.

 

[Jim Logajan]

I'm not sure what to make of some the interpretations I've seen in this thread, so I searched and found what appears to be a reasonable discussion here:

http://www.av8n.com/fly/fuel-gauges.htm

 

[Tom-D]

I'm not sure what to make of some the interpretations I've seen in this thread, so I searched and found what appears to be a reasonable discussion here:

http://www.av8n.com/fly/fuel-gauges.htm

Who ever wrote that uses the same regulations as I already posted, yet came up with the premise that the fuel gauge is not airworthy if not calibrated.

so show me that requirement.

There are two methods of correcting the errors of the system.

1. clean all connections and replace faulty components.

2 as he did by filling the tank and remarking the indicator..

but remember fuel gauges are instruments, and we are not allowed to work on them with out being a certified instrument repair station.

So he makes a graph to get around the rule.

to continue, his work is maintenance, same as weighing the aircraft is maintenance, so how does he enter it into the maintenance records, does his graph become a required placard?

I prefer to simply use the maintenance manual and fix the system.

 

[straightwingedjetsrule]

Who ever wrote that uses the same regulations as I already posted, yet came up with the premise that the fuel gauge is not airworthy if not calibrated.

so show me that requirement.

It's in the regulation.
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. ....

 

[Tom-D]

It's in the regulation.
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. ....

That means to be calibrated in the proper units, liters gallons, pounds, etc. in that usage it meant nothing about accuracy

 

[Jim Logajan]

That means to be calibrated in the proper units, liters gallons, pounds, etc. in that usage it meant nothing about accuracy

So are you saying the regulation is using the term "calibrated" as a synonym with "labeled"?

One dictionary definition of "calibrated" says "To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument)". Simple labeling can be done without comparison to any standard. (I believe that judges are known to check dictionary definitions as part of their deliberations, so just because the FAA doesn't have their own definition doesn't mean a reasonable dictionary definition doesn't have legal weight.)

 

[Tom-D]

So are you saying the regulation is using the term "calibrated" as a synonym with "labeled"?

Engine fuel flow gauges are calibrated in gallons per hour, and pounds per hour to match the fuel quantity gauges.

does that mean they are accurate?

Allowable oil usage is given in pounds per hour, the oil quantity gauges were calibrated in pounds.

If the system were required to be accurate, wouldn't there be an inspection requirement for it at annual or ?

In any reference I can find, the word accurate is not used.

 

[skidoo]

Assume a fuel gauge "calibrated" in terms of E, 1/4, 1/2 (i.e. 2/4), 3/4, and full. In the absence of any specified accuracy, it would be implied to the significant figures. So in performing a Calibration check of that gauge, when filled to indicate 1/4, if the actual quantity were between 0.5/4 and 1.5/4 would comply, and when filled to indicated 1/2, then if the actual quantity were between 1.5/4 and 2.5/4 would comply, and when filled to indicate 3/4, then if the actual quantity were between 2.5/4 and 3.5/4 would comply, and when filled to indicate full, then if the actual quantity were between 3.5/4 and 4.5/4 full would comply and considered accurate. A gauge with more resolution would imply better accuracy, again in the absence of an accuracy specification.

As Tom-D suggested, the context of that reference was that those were calibrated "markings", not necessarily any reference to any accuracy.

 

[wabower]

Are judges doing ramp checks filling POI jobs at your airport? If so, maybe that's the reason the dockets are jammed.

So are you saying the regulation is using the term "calibrated" as a synonym with "labeled"?

One dictionary definition of "calibrated" says "To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument)". Simple labeling can be done without comparison to any standard. (I believe that judges are known to check dictionary definitions as part of their deliberations, so just because the FAA doesn't have their own definition doesn't mean a reasonable dictionary definition doesn't have legal weight.)

 

[skidoo]

Engine fuel flow gauges are calibrated in gallons per hour, and pounds per hour to match the fuel quantity gauges.

does that mean they are accurate?

Yes, they are Accurate... The questions are,

1) How accurate are they? They may be only 25% accurate (i.e. +/- 75% uncertainty), but "accurate" none the less.

As mentioned in my last post, they "Should" be accurate to the significant figures, in the absence of a specification. That is, if they were designed well... Obviously, if someone that did not know what they were doing when designing had used a resolution of 0.0000000001 GPH on the display, when in fact its designed uncertainty were +/- 1 GPH, well that would be very misleading.

and

2) Are they required to be within any particular uncertainty limit?

 

[Jim Logajan]

Are judges doing ramp checks filling POI jobs at your airport? If so, maybe that's the reason the dockets are jammed.

Amusing. I was thinking of the judges who render verdicts in cases like these, where fuel gauge accuracy can arise:

"The fuel gauges were determined to be defective, and the pilots ignored other warnings of low fuel. Executive Airlines and BAE Systems, the plane manufacturer, combined for a settlement of $32,250,000, the largest personal injury settlement in the history of Luzerne County. After legal fees and expenses, 17 families will split approximately $24.845 million.":

http://www.munley.com/newsreleases/bear_creek_case.htm

"The family believes that two fuel gauges were improperly installed, causing them to read inaccurately. They say the gauges showed there was plenty of fuel to make the trip from Redmond to Friday Harbor, Wash.":

http://www.bendbulletin.com/article/20080716/NEWS0107/807160392/

"There is an argument, however, that the actual risk in this case is not the risk of an inaccurate fuel gauge reading, but is instead the risk of relying upon such a minute amount of fuel to stay in the air. The maximum discrepancy in the fuel gauge at issue registered 3.5 percent. The applicable air regulations, CHL policy, the mandates of McLennan's training, the customary practices of experienced slinging pilots, basic airmanship rules, and the manufacturer's instructions about both the low fuel warning light and fuel management generally, all required that McLennan be on the ground long before he approached anything near 3.5 percent remaining fuel, which would have permitted only about 3 minutes flight time to exhaustion. These facts raise serious concerns about whether McLennan carried his burden of proving that the inaccurate fuel gauge reading was the producing cause of his injury or damages.":

http://ftp.resource.org/courts.gov/c/F3/245/245.F3d.403.99-41036.html

And then there are the lawyers who blog on this who also disagree with you and are likely to be looking to make some money off of it:

"The Regulations Do Not Say that the Fuel Gauge Must be Accurate "Only When Reading Zero":
http://www.aviationlawmonitor.com/tags/fuel-gauges/

("The Danko Law Firm represents victims of aviation accidents throughout the United States and abroad.")

So feel free to hold your opinion. See where it leads.

 

[wabower]

At what level of degradation does "accuracy" become "inaccuracy?"

If you completed 25% of the required assignments in one of your college classes, would your transcript grade be "25% complete" or "incomplete?"

Yes, they are Accurate... The questions are,

1) How accurate are they? They may be only 25% accurate (i.e. +/- 75% uncertainty), but "accurate" none the less.

As mentioned in my last post, they "Should" be accurate to the significant figures, in the absence of a specification. That is, if they were designed well... Obviously, if someone that did not know what they were doing when designing had used a resolution of 0.0000000001 GPH on the display, when in fact its designed uncertainty were +/- 1 GPH, well that would be very misleading.

and

2) Are they required to be within any particular uncertainty limit?

 

[wabower]

Do you actually think that any of those references are on point relative to the discussion at hand?

Amusing. I was thinking of the judges who render verdicts in cases like these, where fuel gauge accuracy can arise:

"The fuel gauges were determined to be defective, and the pilots ignored other warnings of low fuel. Executive Airlines and BAE Systems, the plane manufacturer, combined for a settlement of $32,250,000, the largest personal injury settlement in the history of Luzerne County. After legal fees and expenses, 17 families will split approximately $24.845 million.":

http://www.munley.com/newsreleases/bear_creek_case.htm

"The family believes that two fuel gauges were improperly installed, causing them to read inaccurately. They say the gauges showed there was plenty of fuel to make the trip from Redmond to Friday Harbor, Wash.":

http://www.bendbulletin.com/article/20080716/NEWS0107/807160392/

"There is an argument, however, that the actual risk in this case is not the risk of an inaccurate fuel gauge reading, but is instead the risk of relying upon such a minute amount of fuel to stay in the air. The maximum discrepancy in the fuel gauge at issue registered 3.5 percent. The applicable air regulations, CHL policy, the mandates of McLennan's training, the customary practices of experienced slinging pilots, basic airmanship rules, and the manufacturer's instructions about both the low fuel warning light and fuel management generally, all required that McLennan be on the ground long before he approached anything near 3.5 percent remaining fuel, which would have permitted only about 3 minutes flight time to exhaustion. These facts raise serious concerns about whether McLennan carried his burden of proving that the inaccurate fuel gauge reading was the producing cause of his injury or damages.":

http://ftp.resource.org/courts.gov/c/F3/245/245.F3d.403.99-41036.html

And then there are the lawyers who blog on this who also disagree with you and are likely to be looking to make some money off of it:

"The Regulations Do Not Say that the Fuel Gauge Must be Accurate "Only When Reading Zero":
http://www.aviationlawmonitor.com/tags/fuel-gauges/

("The Danko Law Firm represents victims of aviation accidents throughout the United States and abroad.")

So feel free to hold your opinion. See where it leads.