LSA rental has inoperable fuel gauge. How to deal with school to fix it?

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kaputt16
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LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by kaputt16 »

One of the schools I rent from in my local area has a bunch of LSAs for rent. One of their aircraft is a tailwheel that I liked to rent fairly often because it’s used far less than their other aircraft and I have a pretty good amount of tailwheel time.

However, the fuel gauge has stopped working in the aircraft. It’s a digital gauge on a G3X. The entire time you fly the aircraft and no matter what fuel level is in the tanks, it reads 10 gallons on each side. I have heard from a CFI at the school that if you fly long enough the gauges will jump from 10 straight to 3 gallons a side, but I don’t believe anyone has actually tried to prove if that final 3 gallon reading is accurate or not. The issue has been written up as a squawk on the aircraft a few times and I’ve heard unofficially from some instructors at the school that the management thinks it’s an issue with the sensors, but they don’t want to fix it because it would be highly labor intensive (possibly taking the wings off, but the CFIs weren’t sure).

I’m not comfortable flying the plane because the squawks haven’t been addressed and they also haven’t even gone through the trouble of providing a fuel dipstick. I also read the following article on AOPA (https://pilot-protection-services.aopa. ... -attention) and I thinks it’s possible they are actually in violation of the regs.

My conversations with CFIs at the school have made it seem like the ownership has expressed little interest in actually fixing the issue. The advice has apparently been just fill it up to near full and you’ll be good. To me that’s not good enough. An operating fuel gauge is crucial to know if your fuel burn is actually accurate or if you happen to have a leak develop some where in the system. Just because you take off with visually full tanks does not mean you’ll be fine.

I’ve been renting from this school for almost 2 years now and have over 100 hours in their aircraft, so hopefully I have some credibility with them. My question is, what is the best way to address this with the school? I don’t want to come across as threatening them, but I want to address that I think having a faulty fuel gauge in aircraft available for rent is a serious problem and that I think it should be fixed.

Any advice would be greatly appreciated. Thanks!
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by drseti »

If this is a certified aircraft, there's an FAR that requires the fuel gauge to be accurate at one setting only - zero! If the gauge doesn't read zero at empty, the plane isn't airworthy. (Of course, that means that one reading zero all the time is airworthy!)
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
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kaputt16
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by kaputt16 »

drseti wrote:If this is a certified aircraft, there's an FAR that requires the fuel gauge to be accurate at one setting only - zero! If the gauge doesn't read zero at empty, the plane isn't airworthy. (Of course, that means that one reading zero all the time is airworthy!)
So I read that portion of the FAR and also did some research on it because I saw that answer a few other times on the internet. I believe that is the wrong interpretation of the FAR. Here is what the reg states:

(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of us- able 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 re- maining in the tank is equal to the un- usable fuel supply determined under § 23.959(a)

That does not say that the fuel quantity indicator only has to read zero in level flight to be accurate/legal. All that is saying is that the calibration of the indicator must be that in level flight it will read zero when the fuel level is down to unusable fuel supply.

The important part of the reg is: “There must be a means to indicate to the flightcrew members the quantity of us- able fuel in each tank during flight.”
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by Scooper »

Paul, that's funny! :D

Looking at the G3X Installation manual, there's a relatively simple calibration procedure for the fuel gauges. kaputt16 doesn't mention what aircraft he's got the fuel gauge problem with, but typically if the fuel tanks are in the wings and there's some dihedral, the filler caps are outboard while the sensor (most often a float attached to an arm that moves a variable resistor wiper contact as the fuel level changes) is, like the fuel hose connection going to the shutoff valve, at the lowest point in the tank near the wing root. One of the sensor options for the G3X fuel sensor is a 0-500 ohm resistive sensor with voltage on one end of the resistor and ground on the other end, so the voltage at the wiper indicates the amount of fuel in the tank.

Unfortunately, the float will remain at the top of the tank near the wing root until enough fuel has been used such that the level drops below the point where the float starts to show an indication other than full. Fortunately, the float is quite accurate at low fuel levels after the calibration procedure is done. Also, because the plane is a taildragger, it should be calibrated when the tail is elevated to simulate level flight,

It sounds to me like the calibration procedure either wasn't performed or the calibration was somehow erased from the G3X memory.

Page 8-33 of the G3X installation manual describes the calibration procedure. The manual may be downloaded (free) from Garmin at https://static.garmincdn.com/pumac/190-01115-01_0F.pdf
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by drseti »

I like your interpretation, Kaputt, and the FAA may possibly interpret the rule that way. One thing I would never do is ask FAA Legal branch for an official letter of interpretation. We might not like the answer!
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by HornedFrogGrant »

drseti wrote:Of course, that means that one reading zero all the time is airworthy!
And a broken clock is right twice a day. :lol:
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by drseti »

HornedFrogGrant wrote: And a broken clock is right twice a day. :lol:
Exactly!
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by 3Dreaming »

drseti wrote:If this is a certified aircraft, there's an FAR that requires the fuel gauge to be accurate at one setting only - zero! If the gauge doesn't read zero at empty, the plane isn't airworthy. (Of course, that means that one reading zero all the time is airworthy!)
It is my understanding that it must be accurate at both full and empty.
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by drseti »

FAR 91.205(b)(9) does specify that fuel gauges must indicate the quantity of fuel in each tank, but it also specifies that the regulation only applies to aircraft with a standard category airworthiness certificate. Since an SLSA, ELSA, or E-AB will have a special airworthiness certificate, I would conclude that this rule would not apply to such aircraft, and therefore all bets are off with regard to fuel gauge accuracy, or even if one is required.

Further supporting this interpretation, I've flown quite a few experimental aircraft that have no fuel gauges at all, merely uncalibrated sight tubes associated with each tank (which simply tell you if the tanks contain some fuel).
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
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kaputt16
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by kaputt16 »

drseti wrote:FAR 91.205(b)(9) does specify that fuel gauges must indicate the quantity of fuel in each tank, but it also specifies that the regulation only applies to aircraft with a standard category airworthiness certificate. Since an SLSA, ELSA, or E-AB will have a special airworthiness certificate, I would conclude that this rule would not apply to such aircraft, and therefore all bets are off with regard to fuel gauge accuracy, or even if one is required.

Further supporting this interpretation, I've flown quite a few experimental aircraft that have no fuel gauges at all, merely uncalibrated sight tubes associated with each tank (which simply tell you if the tanks contain some fuel).
That is something I did not think of, standard category vs S-LSA. In that case you may be right, the reg would not be applicable technically. Although you would hope a manufacturer and owner/operator would strive to meet as many of those regs as possible!

However, I opened up the POH and a fuel gauge is listed as part of the MEL for the aircraft. And I highly doubt the intent of that is one that is stuck at reading 10 gal a side! :D

Also thanks to the poster who shared the G3X info. It wouldn’t shock me if the calibration is off because it’s a tailwheel. I think I still plan to reach out to them about the issue, including mentioning the regs. Any tips on how to make it not seem like I’m threatening or attacking them?

Edit: wanted to add, great discussion here. I know this isn’t the most busy aviation forum on the internet, but I know I can get good in depth discussion here from some smart and passionate individuals. That’s why I asked here vs some of the other forums!
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by kaputt16 »

Not to run up my post count here, burn tge tricycle gear versions are the school all have accurate fuel readings, and the gauge and gal remaining burns down at the same rate as the fuel in the tank.
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by Scooper »

kaputt16 wrote:Not to run up my post count here, burn tge tricycle gear versions are the school all have accurate fuel readings, and the gauge and gal remaining burns down at the same rate as the fuel in the tank.
I don't think you have to be confrontational at all. Download the G3X installation manual, show the fuel gauge calibration procedure to the school honcho, and explain that it might be a simple fix to get the gauges showing accurate readings. Suggest that it's a flight safety issue; presumably he doesn't want his investment crashing because of fuel starvation.

If you don't mind telling, which make and model is the airplane? It would be interesting to see the amount of wing dihedral and the shape/location of the fuel tanks.

From the installation manual:

The G3X has two fuel calibration curves, the standard ‘in-flight’ or normal flight attitude calibration curve and an optional ‘on-ground’ or ground/taxi attitude calibration curve. The ground/taxi calibration curve can be used for aircraft that have a significantly different attitude when on the ground, such as tailwheel aircraft. If no calibration data is entered for the ground/taxi curve, the normal flight calibration curve will be used when the aircraft is in flight and on the ground. The calibration curve being used to display fuel quantity switches automatically and is determined by GPS groundspeed, indicated airspeed, and height above ground.
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by Warmi »

I with you on this - I keep reading that trusting fuel gauges is silly but to me this is not the only tool to evaluate my fuel situation so in that regard is still very useful. I do absolutely use my fuel gauge during flight as a quick way of evaluating how much I got left, while keeping in mind how much I put in originally and my overall flight time .
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by HornedFrogGrant »

Scooper wrote: I don't think you have to be confrontational at all. Download the G3X installation manual, show the fuel gauge calibration procedure to the school honcho, and explain that it might be a simple fix to get the gauges showing accurate readings. Suggest that it's a flight safety issue; presumably he doesn't want his investment crashing because of fuel starvation.
I agree 100%. A confrontational approach will get you nowhere, more often than not. I think Stan's suggestion is spot-on.
Warmi wrote:I with you on this - I keep reading that trusting fuel gauges is silly but to me this is not the only tool to evaluate my fuel situation so in that regard is still very useful. I do absolutely use my fuel gauge during flight as a quick way of evaluating how much I got left, while keeping in mind how much I put in originally and my overall flight time .
The aircraft I fly has GRT PFD and EIS, and find their fuel indication and fuel burn rate to be pretty accurate, when compared to the dipstick and mental calculation en-route method. The aircraft also has stand-alone fuel gauges, but they're far less accurate.
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Re: LSA rental has inoperable fuel gauge. How to deal with school to fix it?

Post by kaputt16 »

Appreciate all of the responses. For reference the aircraft is a Sling2.

I will reach out to the school management here soon with the G3X guide and see what they say!
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