Inop fuel gauge - what would you do?

PilotAlan said:
Considering the percentage of pilot accidents are caused by fuel exhaustion or starvation, I don't question the reason for this regulation at all.
You must have gauges, and they must work. Sounds simple to me.
Click to expand...

Fuel gauges are only required to be accurate at the empty position.

Even the Glass ones.

The new glass stuff are usually a capacitive type, and they have pots to adjust the empty and full readings and are usually accurate but the old resistance type has too many connections which all contribute to the resistance of the circuit to be accurate.

the other is the clark type where the float only has a magnet that is totally contained with in the tank, no electrics the needle only tries to follow the magnet on the opposite side of the aluminum tank. See the early Cessna 170/172 type of fuel quantity indicators embedded in the wing butt.

they were very accurate
 
Simple-minded, maybe, if you think for a minute that the gages in many aircraft are accurate, or can be made to be accurate. Ain't happening. Wish an easy answer was available, but have never found one.

The best incidation of remaining fuel I can obtain for each set of tanks (2 interconnected Monarchs in each wing) that indicate differently when filled to the same level is:

Quite a bit, but I know that because I just filled up
Some
Lower than I'd like but probably more than I think

The digital EI totalizer, however, is accurate to a gnat's knuckle and is wired to the GPS as well as a dedicate gage.


PilotAlan said:
Considering the percentage of pilot accidents are caused by fuel exhaustion or starvation, I don't question the reason for this regulation at all.
You must have gauges, and they must work. Sounds simple to me.
Click to expand...
 
Last edited:
PilotAlan said:
You must have gauges, and they must work exceedingly poorly per FAA standards, worse than your first used car from the 1970s. Sounds simple to me.
Click to expand...

Heh heh. FTFY.

My $80 1950's technology clock in the IFR panel that the FAA requires over the three other higher quality timing devices on board, does a better job telling me how much fuel is on board. ;) :) :lol:
 
Last edited:
Tom-D said:
Fuel gauges are only required to be accurate at the empty position.
Click to expand...

By that logic, a gauge that is fixed to always indicate the empty position will meet the requirement. It wouldn't have to do anything else.
 
Last Saturday, I went to preflight my G1000 aircraft. It was 28F in the hangar and I powered up the standby and master battery switch, applied charge while pre-heating and preflight. This was the first time I saw the G1000 boot up and leaving one fuel gauge with a red X. I shook the wings a bit up and down, and the red X went away...

I always stick the fuel and quite happy with the accuracy of both the gauges and fuel totalizer. It has always indicated within 1 gallon of the stick total.
 
After all these posts about the lack of accuracy of the Cessna (and other) fuel gauges, I should point out that, though I consider those in my "primary" rental to be accurate, I still visually confirm the readings. I'll also note that this Cessna, at least, does have tabs to determine fuel quantity shy of full. It's still over 4 hours, though, with reserve! Off the top of my head, 89gal as opposed to 64gal. I could still be off a couple of gallons,though!
 
skidoo said:
I always stick the fuel and quite happy with the accuracy of both the gauges and fuel totalizer. It has always indicated within 1 gallon of the stick total.
Click to expand...

Someday it won't. All electronics eventually fail. The stick never will.

Granted it'll give you some weird reading someday when not parked level or with an out of whack nosewheel strut level, but you'll be able to visually see the reason why and reconcile it.

Sticks work. Gadgets break. ;)
 
What would I do? I'd scream until it was fxed...

This is a known issue with the sending units in the tank....It takes a good shop about two hours to fix it...

The gauges in the C182T I fly suck...period...the totalizer has proven accurate time and time again.
 
TangoWhiskey said:
The guy behind the counter expressed surprise when I told him it wasn't working (again), stating that it worked earlier in the week. I said that with the gauges being required for Day VFR, I wouldn't take the plane, even for pattern work. A short conversation ensued where he tried to persuade me, gently, to take the plane, as the gauge worked 'sometimes' and was being 'intermittent' and they were trying to chase down the root cause, perhaps a "short".

:yikes: "Short? Near fuel?!" says I. "No thanks."
Click to expand...

People refer to any electrical problem as "probably a short" in spite of the fact that 99.9725% of the time the real problem is not a short.

Was it safe to fly around the pattern? Probably.

Was it legal? No.

And, one is not likely to be able to "chase down the root cause" if someone else is doing pattern work with the airplane, eh?
 
PilotAlan said:
Regardless, FAR91.205 is binding on all pilots of standard category aircraft, and clearly requires an accurate fuel gauge.
Click to expand...

Nothing in part 91 nor part 23 says anything about the accuracy of the fuel gauges. PERIOD. Things that have accuracy requirements tell you what that is (like 75 feet for an altimeter, etc...).
 
I'd probably fly it. I treat the guages as worthless anyway and stick the tanks + use a stopwatch. that said, i'd be worried in general about your fbo's maintenance practices if they let a 'required' item like this stay inop for so long.
 
I can only think of a handful of older airplanes I've flown that have functioning and accurate fuel gauges. I always check the tanks, regardless of what the aircraft type is.

It seems like the newer stuff w/ glass is more accurate. I still do the stick + fuel burn calculation though.
 
The survey bias here is off the scale. I've found that many, many pilots will fly when I won't, and there are pilots that would express shock at what I've flown.

I have to agree that the biggest flag is how long it's gone not being fixed. If it's gone in for a 100 hour and not been addressed they have no intention of ever fixing it.
 
Tom-D said:
the other is the clark type where the float only has a magnet that is totally contained with in the tank, no electrics the needle only tries to follow the magnet on the opposite side of the aluminum tank. See the early Cessna 170/172 type of fuel quantity indicators embedded in the wing butt.

they were very accurate
Click to expand...

Tom-D said:
Clark style gauge
http://www.ebay.com/itm/vintage-Fue...ors_Aviation_Parts_Gear&vxp=mtr#ht_775wt_1413
Click to expand...

I've never seen one of those before, Tom! Very cool, simple! I assume the gauges were mounted in the wing roots?

Probably the most accurate gauges for their simplicity are the fuel sight tubes installed in the root, visible from cockpit, on Super Cubs, Husky and some other taildraggers.

husky-2.png
 
skidoo said:
Last Saturday, I went to preflight my G1000 aircraft. It was 28F in the hangar and I powered up the standby and master battery switch, applied charge while pre-heating and preflight. This was the first time I saw the G1000 boot up and leaving one fuel gauge with a red X. I shook the wings a bit up and down, and the red X went away...

I always stick the fuel and quite happy with the accuracy of both the gauges and fuel totalizer. It has always indicated within 1 gallon of the stick total.
Click to expand...

Which fuel stick do you use?
 
Sticks only work if the geometry of the tanks allows their use. Many don't.

denverpilot said:
Someday it won't. All electronics eventually fail. The stick never will.

Granted it'll give you some weird reading someday when not parked level or with an out of whack nosewheel strut level, but you'll be able to visually see the reason why and reconcile it.

Sticks work. Gadgets break. ;)
Click to expand...
 
I would have taken it back.

The fun thing about being a renter is that you can see something that should ground the plane, but you know it's still being flown by others.
 
I only have flown two planes with good gauges, a Diamond Katana and my 182.

Howevr my plane only reads 100% accurately when parked. I still visually check however!
 
This was a question on my private checkride haha (I didn't get it right). I think it is ridiculous because I would never trust the fuel gauge vs a visual inspection and my own time/flow calculations.
 
The aircrafts I rent are all 2007 or better 172SPs. If the tanks are topped off, the gauges will always be x'd out. It's been that way on every SP I've flown since training. 4 of them for over 3 years. Of coarse, I do always visually check fuel. And in flight they do finally come online. Anyone else notice this ?
 
N2124v said:
Refresh yourself on ramp check protocol. You have to produce your certificate, medical, and photo ID. For the plane, Air worthiness, registration, operating manual, and weight and balance. The inspector has to have your consent to enter the aircraft.
Click to expand...
While that is true by itself, refusal to allow entry for inspection can be considered a violation of 49 USC 44709 -- and violation of the United States Code is a lot more serious than violation of the Code of Federal Regulations (CFR) under which the FAR's fall. Choose wisely.

Be courteous and professional, but don't provide more information than the basics. Just like a traffic stop.
Click to expand...
Now that's good advice.

For the full "shtick" on Ramp Inspections, see here, and note the following:
2) An inspector must not board any aircraft without the knowledge of the crew or operator. Some operators may prefer to have a company representative present to answer questions.
Click to expand...
 
Last edited:
Tom-D said:
Fuel gauges are only required to be accurate at the empty position.
Click to expand...

Please cite your source for this statement.

I have citied my sources (FAR91.205, and Part 23). Part 23 is quite specific (for those aircraft certified under its requirements).
FAR91.205(b)(9) clearly requires gauges that accurately reflect the amount of fuel remaining.
 
flyingron said:
Nothing in part 91 nor part 23 says anything about the accuracy of the fuel gauges. PERIOD. Things that have accuracy requirements tell you what that is (like 75 feet for an altimeter, etc...).
Click to expand...

Ron, I respect you immensely. But you know that when a reg requires something be in place and functioning, there is an inherent requirement that it be accurate.
The basis is the certification of the aircraft. The gauges have to work and be in conformance with their design. Cessna 172 gauges are notoriously bouncy due to the design of the tank. But that's different than a malfunctioning gauge (one that sticks at 1/2 tank and doesn't move until the fuel level is below that, or doesn't work at all, or flickers full deflection every time the fuel sloshes, all the usual rental bird problems)

I find it ironic that some here will argue to the death that to be airworthy an aircraft must be in exactly the condition that it came from the factory (in conformance with its type certificate) plus any STCs, but will then argue that the fuel gauges don't have to work.
We can argue about tolerance and "how accurate is accurate enough?", but the minimum Day VFR equipment includes functioning (as designed) fuel gauges, period.
 
If the design was defective from the get-go, as in the case of all of the old Cessnas, then what? Must they be functioning in their usual malfuction mode?

PilotAlan said:
We can argue about tolerance and "how accurate is accurate enough?", but the minimum Day VFR equipment includes functioning (as designed) fuel gauges, period.
Click to expand...
 
Tom-D said:
Fuel gauges are only required to be accurate at the empty position.
Click to expand...

Reference please.

Tom, I have looked extensively and I cannot find this in the regs. All I can find is that the gauges must be accurate, with no guidance given as to what "accurate" means. But having a completely inop fuel gauge reading "E" when the tank is verified full doesn't pass the smell test for "accurate".

-Skip
 
PilotAlan said:
Ron, I respect you immensely. But you know that when a reg requires something be in place and functioning, there is an inherent requirement that it be accurate.
Click to expand...
There is no such thing.
The basis is the certification of the aircraft. The gauges have to work and be in conformance with their design.
Click to expand...
Agreed...and that standard for design and certification places no requirements on accuracy. Read through the rest of part 23. When there is a such a requirement, it says so. All it says is that it needs to be calibrated in suitable units and E means the end of usable fuel. There's no specification of what units are suitable (some planes use gallons, some just give some fractional indication of full tanks). There's no more requirement than that. If they wanted it to be accurate within a gallon or whatever tolerance, it would say that.
Cessna 172 gauges are notoriously bouncy due to the design of the tank. But that's different than a malfunctioning gauge (one that sticks at 1/2 tank and doesn't move until the fuel level is below that, or doesn't work at all, or flickers full deflection every time the fuel sloshes, all the usual rental bird problems)
Click to expand...
I never said the gauges don't have to function properly. I said the regs don't make any requirement for accuracy. Do you need me to get you a dictionary to explain what these English words mean?
I find it ironic that some here will argue to the death that to be airworthy an aircraft must be in exactly the condition that it came from the factory (in conformance with its type certificate) plus any STCs, but will then argue that the fuel gauges don't have to work.
Click to expand...
I didn't ever say that the gauges don't have to work. I didn't say that they didn't have to work in accordance to their design/certification.

What I said (to counter the inane suggestion that they only need to be accurate at empty) is that there is NO ACCURACY REQUIREMENTS in the regulations. That is true.
 
Doggtyred said:
Required, so not legal.

Perfectly safe. However. Gasoline tanks are vented but the vapor pressure in the empty space never lets it get lean enough to burn/ignite/explode. Even if there was an arcing wire. Chances are the tank uses capacitance probes which actually involve passing micro current through the fuel to determine its level.

On a side note, I ALWAYS stuck Cessna tanks to know my fuel status no matter what the gauges said.
Click to expand...

The C172's G1000 tank senders are still the potentiometer-type. Like any pot, especially the old wirewound units, they make sparks. In the tank. With the fuel. And it never explodes because, as you say, it's too rich in there. When I drain a tank to remove it, that's when it gets dangerous to have any power to the sender.

Most cars now have electric fuel pumps, with open frames and arcing brushes, in the fuel tanks.

The G1000 senders use a segmented carbon-track pot that has very little pressure on the runner. The float pivot is sloppy and lets the runner's pressure on the track fall off at fuel fuel when the float is forced up all the way. Cheap setup. Homebuilders have had available for a long time already a capacitance gauge setup for less than $100, IIRC. Why Cessna hasn't adopted this technology is beyond me. The flying public complains that GA technology is stuck in the Dark Ages, so Cessna buys G1000 stuff but leaves the unseen, antiquated stuff as it's been for 50 years. Not just float-type gauge senders but felt wheel bearing seals, too. Silly.

At least the G1000 fuel gauges are adjustable. The software has pages for calibrating just about everything in the system. It's not potentiometers as found in some older systems; thankfully. Pots are just a pain. Even when they don't move they eventually quit.

Dan
 
Last edited:
wabower said:
Sticks only work if the geometry of the tanks allows their use. Many don't.
Click to expand...
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.
 
In any event, there can be no question that flying the plane in the OP's original post is not legal. The remaining question is whether it would be safe, and absent an investigation into the cause of the red-X indication, there's no way to know that for sure -- which is why an A&P has to look at a plane before a ferry permit is issued.
 
Fearless Tower said:
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.
Click to expand...

in the 421 wing tanks i recall them being somewhere around 1/3 full when you couldn't see any fuel through the filler neck. It did seem to have pretty accurate fuel gauges though and we kept a close eye on them, cross checking with totalizer and fuel receipts and occasionally would have the mechanics recalibrate them to get them back to reasonable.
 
tonycondon said:
in the 421 wing tanks i recall them being somewhere around 1/3 full when you couldn't see any fuel through the filler neck. It did seem to have pretty accurate fuel gauges though and we kept a close eye on them, cross checking with totalizer and fuel receipts and occasionally would have the mechanics recalibrate them to get them back to reasonable.
Click to expand...
Understand....the Duchess is pretty similar, but how often are you really going to initiate a flight with less than 1/3 in the tank?
 
Fearless Tower said:
Understand....the Duchess is pretty similar, but how often are you really going to initiate a flight with less than 1/3 in the tank?
Click to expand...

well in the 421 the wing tanks are the aux tanks so we would often have full fuel in the tips (main tanks, 50ish gallons each) and partial in the auxes. perhaps some in the locker nacelle tanks too. we flew with all kinds of odd fuel loads thanks to wildly varying passenger loads. it was fun.
 
Skip Miller said:
I seriously doubt that anyone on this thread has a different opinion. :yesnod:

-Skip
Click to expand...

To the contrary, mine seem to be very reliable. It indicates fairly accurately while on level ground, and in flight, I can reliably use them as a backup slip/skid indicator!
icon12.gif
 
TangoWhiskey said:
Which fuel stick do you use?
Click to expand...


I use this one

http://www.sportys.com/PilotShop/product/9338

If I measure 25 gal in the left tank and 28 gal in the right tank, then set the gal remaining on the G1000 for 53 gal, and then if I go fly for 2 hours at 10 gph, and if the totalizer says I now have 33 gal remaining, and if I then go stick the tanks, the total for the two tanks does indeed add to 33 gallons.

I love this system! There is no excuse that I should ever run out of fuel. I Always stick the tank before flight to know the beginning total, know how many gph I plan to use, know how long I need to fly, and use the totalizer to double check as planned.
 
Old Thread: Hello . There have been no replies in this thread for 365 days.
Content in this thread may no longer be relevant.
Perhaps it would be better to start a new thread instead.
Back
Top