Inop fuel gauge on rental + long XC

ChrisK

ChrisK

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The broken equipment / rental threads got me thinking about this, and as a renter...

Here's the scenario.

You check the plane out, do your runup, and everything is fine. You launch on your cross country flight and notice about halfway to your destination that one of your fuel gauges appears to be malfunctioning (fluctuating a lot but reading zero most of the time). You know that that tank should be almost full, and the other tank is reading almost full. What do you do? Turn around? Land? Continue?
 
ChrisK said:
The broken equipment / rental threads got me thinking about this, and as a renter...

Here's the scenario.

You check the plane out, do your runup, and everything is fine. You launch on your cross country flight and notice about halfway to your destination that one of your fuel gauges appears to be malfunctioning (fluctuating a lot but reading zero most of the time). You know that that tank should be almost full, and the other tank is reading almost full. What do you do? Turn around? Land? Continue?
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Land immediately and check it out.

Could be a fuel leak, cap left off, etc. I would never just assume the gauge went bad in the middle of my flight.

If low wing or individually selectable I would switch to the tank showing good prior to landing.

Once on the ground you can go from there.
 
ChrisK said:
The broken equipment / rental threads got me thinking about this, and as a renter...

Here's the scenario.

You check the plane out, do your runup, and everything is fine. You launch on your cross country flight and notice about halfway to your destination that one of your fuel gauges appears to be malfunctioning (fluctuating a lot but reading zero most of the time). You know that that tank should be almost full, and the other tank is reading almost full. What do you do? Turn around? Land? Continue?
Click to expand...

If it was the first time it happened, I would land, and visually check the level to see if it agrees with what the gaue says or not - it may be leaking or venting fuel. If the level in the tank is higher than what the gauge indicates, I would ignore the gauges (which I pretty much do on the original gauges anyway) and do my fuel calcs based on time and fuel burn.
 
I have absolute faith in the fuel gauges when they tell me that I have less fuel then I expect. I have no faith in the fuel gauges if they tell me I have more fuel then I expect. take it from there.
 
My understanding of 91.205 is that you have to have a functioning fuel gauge for every tank, but that they only need to be accurate when the tanks are empty. Is your gauge inaccurate and fluctuating, or is in inoperative? If the former, it's legal, if the latter it's not.

Practically, given how inaccurate most fuel gauges are, I use a generous fuel burn figure and keep a log of time on each tank. This has been an accurate metric for me.
 
EdFred said:
If it was the first time it happened, I would land, and visually check the level to see if it agrees with what the gaue says or not - it may be leaking or venting fuel. If the level in the tank is higher than what the gauge indicates, I would ignore the gauges (which I pretty much do on the original gauges anyway) and do my fuel calcs based on time and fuel burn.
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So at some point you are launching with a known inop fuel gauge, provided there is plenty of fuel but it continues to read zero on the ground. This is kinda what bothers me. I mean, I can understand that losing that one instrument is probably not going to impact the flight, and I would be under a lot of pressure to return myself and the aircraft home eventually. Add on to this the fact that those fuel gauges are not the greatest on a good day. I've seen this happen on more than one aircraft with my own eyes, and it is my impression that the renters are ignoring the inop fuel gauge and using fuel burn calculation solely.
 
aranpura said:
My understanding of 91.205 is that you have to have a functioning fuel gauge for every tank, but that they only need to be accurate when the tanks are empty. Is your gauge inaccurate and fluctuating, or is in inoperative? If the former, it's legal, if the latter it's not.

Practically, given how inaccurate most fuel gauges are, I use a generous fuel burn figure and keep a log of time on each tank. This has been an accurate metric for me.
Click to expand...

To amend my scenario, let's just say that one of the gauges goes to zero and stays there, and let's say we land and see that the tank is almost full, but the gauge continues to read zero on the ground.
 
ChrisK said:
So at some point you are launching with a known inop fuel gauge, provided there is plenty of fuel but it continues to read zero on the ground. This is kinda what bothers me. I mean, I can understand that losing that one instrument is probably not going to impact the flight, and I would be under a lot of pressure to return myself and the aircraft home eventually. Add on to this the fact that those fuel gauges are not the greatest on a good day. I've seen this happen on more than one aircraft with my own eyes, and it is my impression that the renters are ignoring the inop fuel gauge and using fuel burn calculation solely.
Click to expand...

ChrisK said:
To amend my scenario, let's just say that one of the gauges goes to zero and stays there, and let's say we land and see that the tank is almost full, but the gauge continues to read zero on the ground.
Click to expand...

I had a, uh, "friend," yeah, a friend who owned a plane where this was the case. I "heard" that he waited until annual to have it fixed. At least that's what I was "told."
 
Switch to the tank with the bad gauge and start your watch. When it runs out you know if it was the gauge of not. Now you know how much is left in the other tank.

Sent from my Z10 using Tapatalk 2
 
ChrisK said:
So at some point you are launching with a known inop fuel gauge, provided there is plenty of fuel but it continues to read zero on the ground. This is kinda what bothers me. I mean, I can understand that losing that one instrument is probably not going to impact the flight, and I would be under a lot of pressure to return myself and the aircraft home eventually. Add on to this the fact that those fuel gauges are not the greatest on a good day. I've seen this happen on more than one aircraft with my own eyes, and it is my impression that the renters are ignoring the inop fuel gauge and using fuel burn calculation solely.
Click to expand...

You're confusing inaccurate and inoperative. One is legal, the other is not.
 
Alexb2000 said:
If low wing or individually selectable I would switch to the tank showing good prior to landing.
Click to expand...

That's contrary to the 172 POH. Land on both even with one tank empty. That "unusable" fuel may help you in a turn, and the gascolator won't suck air unless BOTH ports are dry.

There is no emergency or "as soon as practicable" landing unless the good tank has low fuel. Keep a 30 minute daytime minimum in the good tank and continue to your destination. Don't overreact. Don't worry about imbalance. Moments are comparable to whether the right seat is occupied or not in a 172.

Once you're on the ground, taking off again with an inop gauge is illegal, so pick a destination where you can either deal with it or get a ferry permit.
 
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Are you most concerned with legality or safety?

It is not difficult to safely operate without a fuel guage, but it does take a little more work to do it legally.
 
What if you have enough fuel in the tank with the good gauge to complete your flight with reserves? What if the bad guage keeps fluctating between where it should be and full, which oddly triggers a low fuel light? I ask because I have experienced this.
 
Alexb2000 said:
Land immediately and check it out.

Could be a fuel leak, cap left off, etc. I would never just assume the gauge went bad in the middle of my flight.

If low wing or individually selectable I would switch to the tank showing good prior to landing.

Once on the ground you can go from there.
Click to expand...

:yeahthat:
 
jtheune said:
I have absolute faith in the fuel gauges when they tell me that I have less fuel then I expect. I have no faith in the fuel gauges if they tell me I have more fuel then I expect. take it from there.
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:thumbsup:.....
 
You have just described the fuel indication system in many older Cessnas, except that after you fly for another hour or so you may notice the gage gradually shows more fuel.

ChrisK said:
To amend my scenario, let's just say that one of the gauges goes to zero and stays there, and let's say we land and see that the tank is almost full, but the gauge continues to read zero on the ground.
Click to expand...
 
wabower said:
You have just described the fuel indication system in many older Cessnas, except that after you fly for another hour or so you may notice the gage gradually shows more fuel.
Click to expand...

The one I'm thinking of is a 1982 Cessna 152.
 
EdFred said:
I had a, uh, "friend," yeah, a friend who owned a plane where this was the case. I "heard" that he waited until annual to have it fixed. At least that's what I was "told."
Click to expand...

I have no idea what you're talking about. Yeah.
 
Many aircraft have junk for fuel gages. King Air comes to mind.

Even the simplest fuel gaging systems can malfunction. I was instructing in a brand new Super Cub, and the sight tube fuel gage stuck on full. I would NEVER have believed that unless I saw it for myself.

P6210002.JPG
 
I actually just had a similar situation yesterday. When I was doing the preflight, I saw that the right tank was on E and the left tank was on about 1/3. When my CFI came out of the FBO I asked him if we were flying light on purpose. He told me that the plane had been flown about 4 hours prior, and that it had been filled up after the last flight, and that the gauges were working properly when they shut down the plane after that flight.

We visually verified that the tanks were both full. We rocked the wings by hand while still on the ground (in case the sensor was stuck), but nothing would budge the gauges.

Knowing full well we had plenty of gas to do touch and goes for an hour, we prepared to launch. As we were taxiing to the run up area, I saw that both tanks were now registering F. We scratched our heads and took off.
 
MAKG1 said:
That's contrary to the 172 POH. Land on both even with one tank empty. That "unusable" fuel may help you in a turn, and the gascolator won't suck air unless BOTH ports are dry.

There is no emergency or "as soon as practicable" landing unless the good tank has low fuel. Keep a 30 minute daytime minimum in the good tank and continue to your destination. Don't overreact. Don't worry about imbalance. Moments are comparable to whether the right seat is occupied or not in a 172.

Once you're on the ground, taking off again with an inop gauge is illegal, so pick a destination where you can either deal with it or get a ferry permit.
Click to expand...

We all read these really quickly, but I said low wing or individually selectable meaning no both position (some Cessna's).

With a both option yes, keep it on both.
 
Alexb2000 said:
We all read these really quickly, but I said low wing or individually selectable meaning no both position (some Cessna's).

With a both option yes, keep it on both.
Click to expand...

You can select individual tanks in a 172. Or a 177 or a 182. Just not a 152. And all of them have a "both" setting.

I think you meant "individually selectED," but it would be clearer just to say "without a 'both' position."
 
MAKG1 said:
You can select individual tanks in a 172. Or a 177 or a 182. Just not a 152. And all of them have a "both" setting.

I think you meant "individually selectED," but it would be clearer just to say "without a 'both' position."
Click to expand...

Your right. Point of trivia, some of the older Cessna high wings (120's and 140's for example) don't have a both setting. Since the OP didn't say what aircraft, I was trying to be through. "Trying" is the word...:D
 
If LH tank was behaving, and I knew it to have fuel, and if RH tank was the misbehaving gauge, I would select RH only, and see where it quit. Once it quit, I would switch to LH tank and land. I would also then have an informed opinion about the accuracy of the RH gauge, and would act accordingly.

I was certain you were describing a Cessna :) Those gauges should just read L . I . E . S instead of E . . . F
 
I'm willing to make a significant wager that it won't be the last time.:wink2:

livitup said:
I actually just had a similar situation yesterday. When I was doing the preflight, I saw that the right tank was on E and the left tank was on about 1/3. When my CFI came out of the FBO I asked him if we were flying light on purpose. He told me that the plane had been flown about 4 hours prior, and that it had been filled up after the last flight, and that the gauges were working properly when they shut down the plane after that flight.

We visually verified that the tanks were both full. We rocked the wings by hand while still on the ground (in case the sensor was stuck), but nothing would budge the gauges.

Knowing full well we had plenty of gas to do touch and goes for an hour, we prepared to launch. As we were taxiing to the run up area, I saw that both tanks were now registering F. We scratched our heads and took off.
Click to expand...
 
aranpura said:
My understanding of 91.205 is that you have to have a functioning fuel gauge for every tank, but that they only need to be accurate when the tanks are empty.
Click to expand...

Sorry, that's incorrect.

91.205 requires "Fuel gauge indicating the quantity of fuel in each tank" for the aircraft to be airworthy.

The confusion about "being accurate when empty" comes from Part 23, which requires (as part of Part 23 aircraft certification) that *unusable* fuel not be included in the gauge indication (if there's 10 gal of unusable fuel, the gauge reads empty when there's 10 gallons remaining).

CAR3 does not take unusable fuel into account, so the gauge can read 10 gals when you're actually at zero usable.

So, Part 91 requires accurate fuel gauges, and "no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation ... unless" they are present. The discussion is what does "accurate" mean, and there's no rulings I know of defining how accurate that is.
But a non-functioning gauge, or one that is all over the place cannot reasonably meet that definition.
 
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I'm not sure I've ever seen an accurate, functioning fuel gauge. OK, they are accurate at least once a flight, but when that is can vary with every flight.
I carry a stick, a watch, and a fuel use chart.
And I don't fully trust those, either.
 
Shepherd said:
I'm not sure I've ever seen an accurate, functioning fuel gauge....
Click to expand...
Mine are. I insist on it and pay for it.
I carry a stick, a watch, and a fuel use chart.
And I don't fully trust those, either.
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I don't trust fuel gauges, but many pilots do not understand the regulatory and airworthiness requirement for their presence and function.
 
I have had different results with fuel gauges....

On my Warrior I owned and flew 30 years ago the gauges were pretty darn accurate. Altho I still used a watch to time the flight....

On my present experimental the VDO gauges that came with the kit are surprisingly accurate... Couple those with the deadly accurate JPI 450 fuel flow gauge and my situational awareness for fuel consumption is more then adaquate, and in fact the JPI is almost perfect in displaying fuel used.. Down to the 1/10 of a gallon..:yes: YMMV...
 
PilotAlan said:
91.205 requires "Fuel gauge indicating the quantity of fuel in each tank" for the aircraft to be airworthy.
Click to expand...


If we are talking about a C-152 which only has an ON and OFF setting both tanks can be considered as one despite the fact that fuel may not feed evenly from both. My 7EC Champ has only one gauge which is installed in the right tank and that's the way it came from the factory.

Regardless, I don't think anyone seriously makes a flight based on what any fuel gauge displays. You should know exactly how much fuel you have at the start and how much you use during operation. The main purpose of a fuel indicator is to alert you to a problem such as leakage or venting. If you have to ask yourself "Why is it doing that?" it's time to land and find out.
 
A plane I rent from time to time had a fuel gauge that read a few gallons low. Eventually, it got stuck at zero irrespective of the quantity of fuel in the tank. It was squawked but never placarded. I suspect it was fixed at annual.

The only fuel that exists to me is fuel that I either measured or put in the tank myself. I go by that and very conservative/padded burn rates.

ChrisK said:
The broken equipment / rental threads got me thinking about this, and as a renter...

Here's the scenario.

You check the plane out, do your runup, and everything is fine. You launch on your cross country flight and notice about halfway to your destination that one of your fuel gauges appears to be malfunctioning (fluctuating a lot but reading zero most of the time). You know that that tank should be almost full, and the other tank is reading almost full. What do you do? Turn around? Land? Continue?
Click to expand...
 
One thing I might add - if you have something like a JPI with fuel flow they are extremely accurate but only as accurate as the idiot who entered the initial data so be very careful about over confidence with such instrumentation.
 
PilotAlan said:
Mine are. I insist on it and pay for it.
Click to expand...
I wouldn't. That's the last thing I'd pay for. Mine are decidedly "good enough" for me. You don't start messing around with the 50 year old circuit board type senders if they already sort of work.
 
wabower said:
You have just described the fuel indication system in many older Cessnas, except that after you fly for another hour or so you may notice the gage gradually shows more fuel.
Click to expand...

The phenomenon of older Cessna fuel gauges gaining fuel in flight is more a matter of siphoning fuel from one tank to another rather than inaccurate gauges...at least in Cardinals and certain years of 182s.
 
Silvaire said:
One thing I might add - if you have something like a JPI with fuel flow they are extremely accurate but only as accurate as the idiot who entered the initial data so be very careful about over confidence with such instrumentation.
Click to expand...

:redface::redface:..

Thank god I am the only "idiot" that flys it and updates the fuel added..;)
 
In which case wouldn't you expect the quantity on the other gage to decrease by more than the estimated amount of burn?

Fearless Tower said:
The phenomenon of older Cessna fuel gauges gaining fuel in flight is more a matter of siphoning fuel from one tank to another rather than inaccurate gauges...at least in Cardinals and certain years of 182s.
Click to expand...
 
aranpura said:
My understanding of 91.205 is that you have to have a functioning fuel gauge for every tank, but that they only need to be accurate when the tanks are empty.
Click to expand...
Which part of 91.205 says that?

In this situation, I apply Riddick's Rule of Maintenance: "If it ain't broke, don't fix it, but if it ain't fixed, don't fly it."
 
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