Fuel Gauges
I'matightbastard
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It continues to be an absolute scandal that after all these years the majority of mainstream light aircraft still have poor fuel indication systems.
Well, if you're picking up the aircraft from the pump and you've seen the refueller's signature in the book it might seem somewhat untrusting to climb up and look inside the tank whilst the guy's watching you
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I read an interesting accident report once.....The refueling guy refueled the aircraft (C172 or something) and left the fuel caps off EXPECTING the pilot to check the fuel. The pilot and his mate wandered out to the aircraft, and decided not to bother going flying, so they left again. Next day, after the aircraft had been sat on the ground over night in the rain with the fuel caps off, another pilot came out to go flying. It was a cold freezing morning, and the pilot saw the caps were off and assumed the aircraft had just been refueled. He drained some fuel and everything looked dandy so off they went. 30 minutes or so into the flight, the engine failed and they crashed. Apparently the tanks got a load of water in, which then froze and so didn't show up when the tanks were drained. During the flight the water melted and stopped the engine.
I also read another report along the same lines. Pilot saw aircraft being refueled, didn't check the fuel. Fuel guy left caps off for pilot to check....except he didn't. Took off, fuel sucked out, engine stop.....you get the drift.
On the subject of accurate fuel guages, most new aircraft have accurate fuel guages, and most panel mounted GPS's have a facility where you can enter your calculated duration / range and it'll keep a running tally on how much fuel you've got left.....All calculated of course, but better than nothing.
I'm paranoid about fuel, for reasons best not discussed in public
EA
I also read another report along the same lines. Pilot saw aircraft being refueled, didn't check the fuel. Fuel guy left caps off for pilot to check....except he didn't. Took off, fuel sucked out, engine stop.....you get the drift.
On the subject of accurate fuel guages, most new aircraft have accurate fuel guages, and most panel mounted GPS's have a facility where you can enter your calculated duration / range and it'll keep a running tally on how much fuel you've got left.....All calculated of course, but better than nothing.
I'm paranoid about fuel, for reasons best not discussed in public
EA
Why do it if it's not fun?
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The tanks... have a sight glass right there in the cockpit, so you know exactly how much fuel you have
A sight guage can't lie to you, but it can certainly mislead you if you don't know how to read it.
FFF
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Englishal
I have sen the same problem with filler caps on, where the rubber seals had perished. This is common in flying school planes, particularly PA38s. I once drained out about a pint of water (!!) after a night of heavy rain.
Re the fuel totaliser, one needs a flowmeter, e.g. a Shadin, coupled to the GPS. The GPS gets an RS232 data stream from the flowmeter, giving the flow rate and the remaining fuel, and it projects the reserve at the flight planned destination. It's a nice feature, though not essential to flight safety because I always fly with at least 2hrs reserve. I suppose it would be handy after a series of emergency weather diversions...
I don't think a GPS can do this alone (without a flowmeter) - certainly it would not be accurate because it won't know the flow rate.
I have sen the same problem with filler caps on, where the rubber seals had perished. This is common in flying school planes, particularly PA38s. I once drained out about a pint of water (!!) after a night of heavy rain.
Re the fuel totaliser, one needs a flowmeter, e.g. a Shadin, coupled to the GPS. The GPS gets an RS232 data stream from the flowmeter, giving the flow rate and the remaining fuel, and it projects the reserve at the flight planned destination. It's a nice feature, though not essential to flight safety because I always fly with at least 2hrs reserve. I suppose it would be handy after a series of emergency weather diversions...
I don't think a GPS can do this alone (without a flowmeter) - certainly it would not be accurate because it won't know the flow rate.
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Englishal, I accept that new aircraft are better but the vast majority of light aircraft being used now are most certainly not new. Can there surely not be a postmod available to refit these aircraft ?
You also mention GPS which is I suppose is something, it is however totally dependent on what you type in and it can only calculate from what you have told it. Aircraft with 2 or 3 FMS's have still run out of fuel eg Gimini Glider, Hapag Airbus etc.
You also mention GPS which is I suppose is something, it is however totally dependent on what you type in and it can only calculate from what you have told it. Aircraft with 2 or 3 FMS's have still run out of fuel eg Gimini Glider, Hapag Airbus etc.
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Deano,
For the PA28-140, 180 and Arrow II;
Full Tank - 25USG
Tab - 17USG
Base of the Outer Tank Wall - 10USG
Unuseable - 1USG per tank (this can be less in pre 1973 models so check the book!!)
Don't think anyone will bother going anywhere with less than 9USG useable!!!......or if one does, it won't be very far !!
The only thing I really use the gauges for is to detect a leak!! and even then the chances are that if it is a big leak, the tank will buckle and freeze the gauge!!
Regards,
DFC
For the PA28-140, 180 and Arrow II;
Full Tank - 25USG
Tab - 17USG
Base of the Outer Tank Wall - 10USG
Unuseable - 1USG per tank (this can be less in pre 1973 models so check the book!!)
Don't think anyone will bother going anywhere with less than 9USG useable!!!......or if one does, it won't be very far !!
The only thing I really use the gauges for is to detect a leak!! and even then the chances are that if it is a big leak, the tank will buckle and freeze the gauge!!
Regards,
DFC
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it is however totally dependent on what you type in
No substitute for a proper fuel guage, though it can draw your attention to a possible low fuel state or remaining range. Ideally it would have a flow sensor on the fuel so it knows really how much you've used...
EA
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A sight guage can't lie to you, but it can certainly mislead you if you don't know how to read it
If the gauge is of the flexible pipe design and the pipe takes a relatively tortuous route from the tank, then trapped air bubbles can form giving a false reading. This is particularly applicable to aerobatic aircraft such as the Pitts. I am aware of at least one engine stoppage resulting from the pilot believing he had more fuel than he actually had for exactly this reason.
Last edited by TheAerosCo; 4th Dec 2003 at 22:34.
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I always like to check the caps and drains after being fuelled, and it seems sensible to check how much you get fuelled with after a flight, so you can get a rough fuel burn.
Example: the twin I fly burns about 18 gal / hour in general training, and at 65 % power. That means about 2.5 hours are in the mains, and 3 hours in the aux tanks.
Typically the left main gauge indicates 1/4 full when it is really at 3/4s. The right main indicates correctly. I'd be pretty unhappy with this if I was on a long flight and switching back to a low-looking main with a descent and approach to shoot.
Example: the twin I fly burns about 18 gal / hour in general training, and at 65 % power. That means about 2.5 hours are in the mains, and 3 hours in the aux tanks.
Typically the left main gauge indicates 1/4 full when it is really at 3/4s. The right main indicates correctly. I'd be pretty unhappy with this if I was on a long flight and switching back to a low-looking main with a descent and approach to shoot.
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The pilot should always be the last one to check and fasten the fuel caps even after refuelling, then he has only himself to blame if they come off in flight.
I once ran a fuel tank dry on a TB10, took a few moments to realise what was going on.
Having been distracted by an aircraft being towed and needing to get past me at the hold forgot to change to the higher tank for dep.! One hour into flight the engine started to stop.
i may have noticed the lack of fuel in that tank if the fuel gauges at worked. They always read 1/4 full.
I knew the fuel gauges were faulty and they are built as one unit with i think from memory oil press./temp gauges. The unit was going to cost £1000 to replace back in 1992.
So as a club we just put up with it.
A disaster waiting to happen.
We would'nt put up with a us airspeed indicator so why to be put up with crappy fuel gauge systems. I've known Cessna fuel gauges show full when empty and virca versa. This usually happens when the refueller accidentlty pressurises the tank by not releasing the nozzle handle quick enough because not paying attention to the fact the fuel is reaching the top of the tank.
All the cars i have driven have always had very reliable fuel gauge systems. But there again most of those aren't 25 yrs old.
I once ran a fuel tank dry on a TB10, took a few moments to realise what was going on.
Having been distracted by an aircraft being towed and needing to get past me at the hold forgot to change to the higher tank for dep.! One hour into flight the engine started to stop.
i may have noticed the lack of fuel in that tank if the fuel gauges at worked. They always read 1/4 full.
I knew the fuel gauges were faulty and they are built as one unit with i think from memory oil press./temp gauges. The unit was going to cost £1000 to replace back in 1992.
So as a club we just put up with it.
A disaster waiting to happen.
We would'nt put up with a us airspeed indicator so why to be put up with crappy fuel gauge systems. I've known Cessna fuel gauges show full when empty and virca versa. This usually happens when the refueller accidentlty pressurises the tank by not releasing the nozzle handle quick enough because not paying attention to the fact the fuel is reaching the top of the tank.
All the cars i have driven have always had very reliable fuel gauge systems. But there again most of those aren't 25 yrs old.
I've got a rotating bezel driven by a float in the Auster, ie completely mechanical. It's the original 1946 gauage as far as I know. On the ground it underreads by 3 gallons and in straight & level flight it underreads by 2 gallons. I've verified this by putting a known quantity of fuel in it. At least it errs on the safe side! It's nearly as accurate as the wire on a stick that is fitted to the J3 / L4 Cub.
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Imust admit to never really taking fuel gauges seriously (on a 152), I've always flown with at least 1/2 tanks and generally fly for one hour. What amazes me is a few clubs don't seem to have any fuel record on their tech logs. When I learnt to fly the t/l was annotated when tanks filled making fuel calculations easier. Also I wonder howm many of these cut down broom handles I see are calibrated in any way?
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Sliding member
What amazes me is a few clubs don't seem to have any fuel record on their tech logs
That sort of record is worth less than the paper it is written on. Always do a physical check, and if one is not possible (because due to W&B you "have" to fly with the fuel level below where it is visible) then take on enough fuel at the pump such that even if the tank was empty to start with you could complete the planned flight with reserve. Might need to re-calc W&B though.
The recent well publicised incident (G-OMAR) involving an unsuccessful CAA prosecution shows these records are completely and utterly worthless. Relying on them does appear to be legal though!! Perhaps because airliners do it routinely (but they have good equipment) and the CAA could hardly admit openly that most light planes have useless gauges...
I have seen two cases of "3.5hrs" in the logs and empty tanks, and that was on PA28s. No idea how often it happened on Cessnas; I trained on them but never checked them (if going solo, always went to pumps and got a gollocking from the CFI occassionally...)
What amazes me is a few clubs don't seem to have any fuel record on their tech logs
That sort of record is worth less than the paper it is written on. Always do a physical check, and if one is not possible (because due to W&B you "have" to fly with the fuel level below where it is visible) then take on enough fuel at the pump such that even if the tank was empty to start with you could complete the planned flight with reserve. Might need to re-calc W&B though.
The recent well publicised incident (G-OMAR) involving an unsuccessful CAA prosecution shows these records are completely and utterly worthless. Relying on them does appear to be legal though!! Perhaps because airliners do it routinely (but they have good equipment) and the CAA could hardly admit openly that most light planes have useless gauges...
I have seen two cases of "3.5hrs" in the logs and empty tanks, and that was on PA28s. No idea how often it happened on Cessnas; I trained on them but never checked them (if going solo, always went to pumps and got a gollocking from the CFI occassionally...)
