Inop fuel gauge - what would you do?

TangoWhiskey

TangoWhiskey

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So, a C172 I sometimes rent, G1000, had the right fuel gauge showing a big red 'x' last time I went to fly it a couple months back. Quick check of the 'required equipment' list confirms that even for day VFR, both L and R fuel gauges must be working, so I scrubbed that flight and made a note to the FBO manager and on the dispatch squawk sheet.

Fast forward to today, 2 months later. Booked the same plane for some lunch T&Gs. I always go out to the plane first thing when I get there to click the power on and check fuel levels, so I can accurately compute W&B and determine if I need to take on fuel before departure. Well, dang if the right fuel gauge isn't still showing a big red 'x'!

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."

"Well, the wires on the gauges and floats are all encased, not exposed."

I explained that they are SUPPOSED to be encased, not exposed, but since they hadn't yet tracked down the root cause of the "intermittent short", who knows?! I didn't want to lose a wing in an explosion on downwind, and declined to fly the plane, and took a round gauge 172 instead. Had a pleasant flight.

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.
 
I've been in that situation, and the only place that airplane went was on a ferry permit to a shop. And it did take several "visits" until it was fixed for good.
 
Yes, if the plane is experimental. :rolleyes:

You must be able to check fuel two ways in a fuel tank. If the gage is defective dip the tank with a measuring stick or look inside to see what you have.

It is not illegal to fly if the gage is inop., not in experimental anyway. ;)

Did I mention how much simpler and less expensive experimentals are? :D
 
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Geico266 said:
You must be able to check fuel two ways in a fuel tank. If the gage is defective dip the tank with a measuring stick or look inside to see what you have.

It is not illegal to fly if the gage is inop.
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It is if the AFM says it is. And in G1000 Cessna's, the Quantity Indicator is REQUIRED for all operations. See the table in the limitations section.

Edit: I see you changed your language to reference experimentals. That's true.
 
In many Cessnas you can't tell by looking whether or not the float gages are working. Even if they are "working" or "operative" or whatever other word is applicable, the indicated level on the gage is worthless to the pilot. Furthermore, the controlling reg states that the gages are required to be accurate only when the tanks are empty.

As a result, I have developed other methods to track fuel quantity and don't often look at the gages anyway other than as a matter of curiosity. Could the trip have been flown safely by sticking the tank with the inop gage and using fuel from that tank (assuming the quantity is adequate) until such time as you need the fuel in the tank with the operative gage?
 
TMetzinger said:
It is if the AFM says it is. And in G1000 Cessna's, the Quantity Indicator is REQUIRED for all operations. See the table in the limitations section.

Edit: I see you changed your language to reference experimentals. That's true.
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Even if the AFM didn't say it - 91.205 calls for it. Of course 91.205 doesn't apply to experimentals - so it'd come down to the operating limitations that particular experimental has. I haven't ever read these so I have no idea if they ever call out fuel gauges.
 
TMetzinger said:
It is if the AFM says it is. And in G1000 Cessna's, the Quantity Indicator is REQUIRED for all operations. See the table in the limitations section.

Edit: I see you changed your language to reference experimentals. That's true.
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Yea, I like to type then proof read. That can be misleading. ;)
 
Makes me nervous, wondering what messages this busy--and previously perfect maintenance FBO, which is why I rent there--might be sending to students. They've been flying it actively for two months. Doubt I simply stumbled on the only two times it had an inop gauge.

Sent from my DROIDX using Tapatalk
 
Well, it's always possible that the plane is on an MEL that allows for operating for some period of time as long as the tank is topped off at each landing! Unlikely to find an MEL on a 172, but I seem to recall seeing something similar on an SEL MEL before.

But absent one of those alternatives, yeah, walking away is the right move.
 
wabower said:
Furthermore, the controlling reg states that the gages are required to be accurate only when the tanks are empty.
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That's only partly accurate.

23.1337(b) states that the fuel quantity indicators installed must be calibrated in appropriate units and clearly marked to indicate those units. In addition, they must be calibrated to read "zero" in level flight when the fuel remaining quantity is equal to the unusable fuel supply.

Your gage must be calibrated. So yes, it must work.

It must be calibrated to read "zero" (empty) in level flight when you're out of usable fuel.

I flew an early Citation 500 once with an INOP fuel gage. Well, it wasn't entirely "inop" but it was a replaced gage and hadn't been calibrated, so we had to get a ferry permit. Not the end of the world. But without the special flight permit, no I wouldn't have flown the aircraft. You did the right thing.

-mini
 
IIRC, only part 3 certified aircraft are legal it the gauge reads accurately and FULL and at EMPTY.

A G1000 C172 is hardly a part CAR 3 aircraft...... sigh.
 
Paris sunk.jpg

The left wing fuel gage on this G-V was never exactly right after repairs from this cluster on the ramp in Paris, but we flew it around the world a quite a few times afterwards.

Which has very little to do with the accuracy of Cessna fuel gages. Do you rely on them or not?

straightwingedjetsrule said:
That's only partly accurate.

23.1337(b) states that the fuel quantity indicators installed must be calibrated in appropriate units and clearly marked to indicate those units. In addition, they must be calibrated to read "zero" in level flight when the fuel remaining quantity is equal to the unusable fuel supply.

Your gage must be calibrated. So yes, it must work.

It must be calibrated to read "zero" (empty) in level flight when you're out of usable fuel.

I flew an early Citation 500 once with an INOP fuel gage. Well, it wasn't entirely "inop" but it was a replaced gage and hadn't been calibrated, so we had to get a ferry permit. Not the end of the world. But without the special flight permit, no I wouldn't have flown the aircraft. You did the right thing.

-mini
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bbchien said:
IIRC, only part 3 certified aircraft are legal it the gauge reads accurately and FULL and at EMPTY.
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I'm afraid that's an old wive's tale (or old pilot's tale).
FAR 91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.

(b) Visual-flight rules (day). For VFR flight during the day, the following instruments and equipment are required:
....
(9) Fuel gauge indicating the quantity of fuel in each tank.
Click to expand...

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.
 
I would have done the same thing. I would not feel comfortable flying an aircraft with intermittent fuel gauges, legal or not. I think you made the right choice.
 
I can see not flying it for legal reasons, but operational concerns? Needing a fuel gauge to do T&Gs in a C172? For how long?:dunno:
 
gprellwitz said:
Well, it's always possible that the plane is on an MEL that allows for operating for some period of time as long as the tank is topped off at each landing! Unlikely to find an MEL on a 172, but I seem to recall seeing something similar on an SEL MEL before.

But absent one of those alternatives, yeah, walking away is the right move.
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Fuel gauges can be deferred under an MEL but it's doubtful the 172 in question would have one. I looked on this site for one but the smallest Cessna I could come up with was a 310/320.

20111129-r9pdcepf2p5abbignsru9uf492.png
 
Everskyward said:
Fuel gauges can be deferred under an MEL but it's doubtful the 172 in question would have one. I looked on this site for one but the smallest Cessna I could come up with was a 310/320.
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The flight school I did my primary training at had an MEL for one of their 172s. I don't know if its still there or not, but I don't remember if the fuel quantity gauges were MELable. My guess is probably not.
 
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.
 
denverpilot said:
Ditto. AFTER sticking the tank.

In fact I always stick the tanks. Fuel gauges in Cessnas are complete junk.
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Fuel guages in just about any light GA airplane are complete junk. I put fuel gauges in the same category of importance as panel mounted clocks. You need it to be 'legal' but there are far better portable options out there to rely on in flight.
 
Doggtyred said:
On a side note, I ALWAYS stuck Cessna tanks to know my fuel status no matter what the gauges said.
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That is one advantage Pipers and some Beech planes have over Cessnas. With the tabs built into the filler neck, it is much easier to estimate how much fuel is in the tank when it is not full.
 
wabower said:
Furthermore, the controlling reg states that the gages are required to be accurate only when the tanks are empty.
Click to expand...

Sorry Wayne, but this is one of those old wives' tales.

The FARs clearly call for fuel gauges for all installed tanks, and a different FAR requires that all instruments be accurate. Now "accurate" is not defined, but even considering that this is a FAR, it is truly a stretch to say "accurate only when empty" fits this definition.

I did some searching a few years ago, and found that there is a FAR that requires that the gauges read zero when there is no usable fuel left. This sounds suspiciously like the source of the OWT. But: :dunno:

This is a point of calibration. It ensures that there is consistency across all planes made under that FAR as to what the big "E" means on the gauges. Well, at least they are consistent when the planes roll out of the factory. Nobody is arguing that the gauges are worth much after 40 years and more since they left the factory.

-Skip
 
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Fearless Tower said:
That is one advantage Pipers and some Beech planes have over Cessnas.
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Yep. The gauges in my Piper are rock reliable, and dead accurate, and I pay to keep them that way. Three years ago I paid to have the senders rebuilt.
I just flew from Denver to Tampa and back, and at every fill up, the fuel remaining matched the gauges.
 
my right fuel gauge doesnt always come alive when I turn the master on, but always between me flicking it and the bumps during taxi it starts working before takeoff
 
In which case the Cessna fleet should have never been certified.
PilotAlan said:
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.
Click to expand...
 
I flew them when they were new, and they weren't any better than they are now. And you're probably right about the fuel gage regs. I just know they are totally unreliable and everything else is irrelevant.

In the case of STC'd airplanes equipped with interconnected Monarch tanks, the gages are even more unreliable because the aux fuel gravity feeds into the mains (seeking the level of the mains) so the float rides at a lower level than normal for any given percentage remaining in the tanks.

Skip Miller said:
Sorry Wayne, but this is one of those old wives' tales.

The FARs clearly call for fuel gauges for all installed tanks, and a different FAR requires that all instruments be accurate. Now "accurate" is not defined, but even considering that this is a FAR, it is truly a stretch to say "accurate only when empty" fits this definition.

I did some searching a few years ago, and found that there is a FAR that requires that the gauges read zero when there is no usable fuel left. This sounds suspiciously like the source of the OWT. But: :dunno:

This is a point of calibration. It ensures that there is consistency across all planes made under that FAR as to what the big "E" means on the gauges. Well, at least they are consistent when the planes roll out of the factory. Nobody is arguing that the gauges are worth much after 40 years and more since they left the factory.

-Skip
Click to expand...
 
Buy your own plane, maintain it to your standards, quit putting up with sloppy excuses from the rental joint.
 
Who would bust you for flying with a bad gauge? Really need to question a lot of the regulations out there and how effective they are at promoting safety.
 
N2124v said:
Who would bust you for flying with a bad gauge? Really need to question a lot of the regulations out there and how effective they are at promoting safety.
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Ramp check????

Oh Geeeez, it worked when I flew it here.

If you want to get rentals fixed, make the FBO spend money getting a mechanic out to you to fix the aircraft before you fly it home.
 
Tom-D said:
Ramp check????

Oh Geeeez, it worked when I flew it here.
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And that is the problem with the G1000 in the OP's question. It is alot easier to fudge your way through a ramp check with questionable old style gauges and another when the fuel gauge displays a big red X on it when powered up.
 
N2124v said:
Really need to question a lot of the regulations out there and how effective they are at promoting safety.
Click to expand...

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.
 
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. Be courteous and professional, but don't provide more information than the basics. Just like a traffic stop.
 
Regarding the MEL in small aircraft, I've seen one on a 182 (and someone else referenced one on a 172).

And regarding accuracy, I've actually found the accuracy of the fuel gauges in the 1999 182 I frequently fly to be pretty good.

All of which is beside the point. again, I agree that, given the circumstances presented, it wouldn't have been legal to fly the G1000 172 in question. Now, are we arguing over whether you would get caught? I sure hope we're not!
 
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