If a high percentage of aircraft accidents...

Timbeck2

Timbeck2

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Timbeck2
...involve fuel starvation, and the only accuracy requirement of a fuel gauge is when it is empty, why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?

I'm not talking about your FADEC stuff, I'm talking about the average Joe flying his Cessna 172 or Cherokee 140 around.
 
I didn't like all of the tenets of Six Sigma, when I was a Data Analyst, but one stuck with me: Gather baseline data before developing a plan.
So, for my benefit: What percentage of GA incidents are caused by fuel starvation?
TIA.
 
by accurate, you mean something beyond indicating usable quantity?

(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable fuel in each tank during flight. An indicator calibrated in appropriate units and clearly marked to indicate those units must be used.
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Timbeck2 said:
...involve fuel starvation, and the only accuracy requirement of a fuel gauge is when it is empty, why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?

I'm not talking about your FADEC stuff, I'm talking about the average Joe flying his Cessna 172 or Cherokee 140 around.
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Because the FAA doesn't want pilots to be safer. I've tried a number of times to install a capacitance system on my Comanche and get stonewalled every time.
 
Timbeck2 said:
If a high percentage of aircraft accidents...involve fuel starvation...
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Bzzzt. Your assumption is wrong. Less than 1% of Cessna 172 accidents involve fuel starvation. Other types are higher, but still less than 5% or so.

Or did you mean "Fuel Exhaustion"? The percentage is higher, but not what I would consider a "High Percentage" (less than 6% for Cessna 172s).

Ron Wanttaja
 
I read somewhere that the "only required to be accurate when empty" was not true.
 
The law requires, as quoted above, that the pilot have a means to determine the quantity of useable fuel in each tank during flight. A dead gauge is indeed accurate when the tank is empty (actually, the law requires the gauge to read empty at the unusable fuel level, not totally empty) but the rest of the requirement obviously requires the gauge to be working and giving a reasonable indication of fuel level.

§91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.
(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.

(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.


§23.1337 Powerplant instruments installation.
(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable 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 remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

§23.959 Unusable fuel supply.
(a) The unusable fuel supply for each tank must be established as not less than that quantity at which the first evidence of malfunctioning occurs under the most adverse fuel feed condition occurring under each intended operation and flight maneuver involving that tank. Fuel system component failures need not be considered.

(b) The effect on the usable fuel quantity as a result of a failure of any pump shall be determined.

 
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Dan Thomas said:
The law requires, as quoted above, that the pilot have a means to determine the quantity of useable fuel in each tank during flight. A dead gauge is indeed accurate when the tank is empty (actually, the law requires the gauge to read empty at the unusable fuel level, not totally empty) but the rest of the requirement obviously requires the gauge to be working and giving a reasonable indication of fuel level.

§91.205 Powered civil aircraft with standard category U.S. airworthiness certificates: Instrument and equipment requirements.
(a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.

(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.


§23.1337 Powerplant instruments installation.
(b) Fuel quantity indication. There must be a means to indicate to the flightcrew members the quantity of usable 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 remaining in the tank is equal to the unusable fuel supply determined under §23.959(a);

§23.959 Unusable fuel supply.
(a) The unusable fuel supply for each tank must be established as not less than that quantity at which the first evidence of malfunctioning occurs under the most adverse fuel feed condition occurring under each intended operation and flight maneuver involving that tank. Fuel system component failures need not be considered.

(b) The effect on the usable fuel quantity as a result of a failure of any pump shall be determined.
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This is the right answer, despite people constantly repeating the totally wrong "only accurate at empty" nonsense. A lack of reading comprehension skills leads to that result.
 
Timbeck2 said:
...why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?

I'm not talking about your FADEC stuff, I'm talking about the average Joe flying his Cessna 172 or Cherokee 140 around.
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Wouldn't a fuel totalizer like the JPI FS-450 or Garmin G1000 fit that bill?
 
Timbeck2 said:
...involve fuel starvation, and the only accuracy requirement of a fuel gauge is when it is empty, why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?

I'm not talking about your FADEC stuff, I'm talking about the average Joe flying his Cessna 172 or Cherokee 140 around.
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That's not the problem. It's all about poor planning and stretching the limits of the airplane.
 
[QUOTE="Timbeck2, post: 2103237, member: 26872why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?QUOTE]

Now that's a question that has been asked and discussed for decades. Yup.
 
The design of fuel tanks makes them difficult to gauge accurately. Wing tanks, especially, tend to be rather flat and/or oddly shaped to fit whatever part of the wing they're in. The fuel moves around in there a lot and the sender float is all over the place. Dihedral adds another dimension to the problem. Large airplanes deal with it by using capacitive gauges, with several strategically-placed senders that are summed to give a good, steady, accurate indication as the fuel moves around. Some light airplanes use capacitance gauges, too, but with one sender that has most of the disadvantages of the old variable-resistance senders most of us have.

A good multi-point capacitive system would add considerably to the cost of the airplane. Nobody wants that. Retrofitting such a system would be enormously expensive, which is why we don't see such STCs.

My Jodel has a direct-reading mechanical gauge that I built for it. Deadly accurate. But that fuselage-mounted tank is relatively deep in relation to its width and length and the float is in the center, where the variation due to sloshing is minimal. Wing tanks can't match that.
 
asicer said:
Wouldn't a fuel totalizer like the JPI FS-450 or Garmin G1000 fit that bill?
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Totalizers don't report fuel leaks. Only a direct-reading tank gauge can alert the pilot to unanticipated loss of fuel overboard.
 
I've been flying most of my life.
The only planes I've ever seen with consistently accurate fuel gauges were those with sight gauges like those in the old Pa-11/12/18 Cubs, etc.
One of the Cessnas I'm currently flying works fine to 3/4 full then the gauge sits there until minutes before the engine stops running. I know how much fuel burns off in what amount of time at a particular altitude and throttle setting, and never fly it "outside the box" and never for more than 3 hours.
Some planes are less accurate than that one. :)
 
bradg33 said:
This is the right answer, despite people constantly repeating the totally wrong "only accurate at empty" nonsense. A lack of reading comprehension skills leads to that result.
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The law can say what it says, but in my experience I wouldn't trust most basic fuel gauges at all....
 
ircphoenix - I use the Wing Monkey - He crawls out of the baggage area and opens the door climbs out on the wing and sticks the tanks
if the fuel quantity is not to plan - he gets back into the aircraft beats me with a stick - grabs a parachute and leaves.

Capacitance is not the answer for Avgas and GA - ask Piper on the new Digital Mirage and Matrix system

There are new fuel quantity designs - and they predominate in new delivered aircraft. Over 75% of new delivered aircraft have fuel quantity systems that are not resistive or capacitive.

Seriously - this is the official interpretation from the FAA Small Aircraft Directorate and the Seattle Aircraft Certification Office - for fuel gauges in GA Aircraft

To achieve a FAA compliant Fuel Quantity indication in the cockpit as required by Part 91 and 135 operating rules.

The fuel gauge is to read from full to empty for each tank,

· Where EMPTY is the FAA flight test determined and Type Certificate Data Sheet, or aircraft Maintenance Manual published aircraft “zero usable fuel quantity" Indentified as C in the fuel tank level illustration below.

· Where FULL is the published maximum fuel level indicated on the TCDS and fuel tank placard. Identified as D in the fuel tank level illustration below.

A FAA compliant fuel quantity system is to accurately read remaining Usable Fuel quantity per the aircraft FAA Approved Maintenance Manual requirements in any position between FULL and EMPTY values in level flight.

The FAA compliant display will drop consistently from FULL to EMPTY with the draining of the fuel tank in normal flight attitude in still air.


Calibration is achieved by the TSO instrumentation requirements or procedures listed in the FAA Approved Aircraft Maintenance Manual. Absent a listed procedure the following applies:

· The aircraft will be jacked and leveled.

· The aircraft will be emptied of fuel.

· Unusable fuel will be added to the tank.

· Confirm the cockpit display reads EMPTY and are within the tolerances established by the FAA Approved Aircraft Maintenance Manual if provided.

· Any numerical value on the cockpit display will be confirmed and checked by adding that value of fuel to the tank in addition to the unusable fuel.

· FULL fuel will be checked in a similar manner where the gauge will read Full.

For example:

If the gauge has markings at 5, 10, 15 gallons - that amount of fuel will be added and the cockpit display checked to ensure that gauge accuracy is maintained. (within the tolerances established by the FAA approved Aircraft Maintenance Manual).

REQUIREMENTS:

While the XXXX. fuel sender is FAA TSO C55a approved and has met a quality standard of 0.75% of tank capacity, that standard can only be met in the aircraft installation if and only if, the aircraft instrumentation, whether that instrumentation is TSO’d C55a or not, has the capability of accurately displaying at that level of sender accuracy.

A fuel quantity installation that meets the requirements of this manual must be able to effectively move between zero fuel and full providing an accurate representation of usable fuel in the cockpit.

Oscillations of fuel quantity ±4% of tank capacity in level flight, still air will require a replacement/refurbishment of the cockpit indication system to achieve an FAA compliant installation.

If the TCDS (Type Certificate Data Sheet) zero fuel level (EMPTY) cannot be indicated in the cockpit with the XXXX fuel sender(s) installed, the fuel quantity indication system is not compliant with the FAA Part 23 regulations and must be removed and the aircraft returned to its former configuration.

If the TCDS (Type Certificate Data Sheet) FULL usable fuel level cannot be indicated in the cockpit with the XXX fuel sender(s) installed, the fuel quantity indication system is not compliant with the FAA Part 23 regulations.

And must be removed and the aircraft returned to its former configuration.

A fuel quantity installation that meets the requirements of this manual must be able to effectively meet the numerical, warning or cardinal indications present on the cockpit display or requirements of the POH or Service Bulletin. Absent a Aircraft Maintenance Manual tolerance indication, cockpit indicated values found in the POH and on the cockpit indication itself will fall within +1% and -3% of full tank capacity.

A low fuel annunciated warning may be incorporated that meets the requirements of the aircraft POH or FAR mandated operational requirements.
 

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Aircraft fuel tanks are not difficult to measure. Aircraft fuel tanks are difficult to measure with tractor senders intended for 20 gallon fuel tanks.

Full is an Accurate value and so is 1/2 and so is 15. Full is a published accurate value found on your fuel tank placard and in your POH.

Broken appears to have wide berth with fuel level.
 
I don't even trust the fuel gauge in my car. I'll be damned if I'll trust one in an aircraft. The most accurate gauge involves a dipstick, a watch, and a couple of brain cells.
 
Yes and using that method - the accident statistic we are talking about stays remarkably fixed.

Therefore - I don't trust that time honored method as it hasn't proven itself to be fool proof.

I'll stick with the Wing Monkey
 
Scott Philiben said:
Yes and using that method - the accident statistic we are talking about stays remarkably fixed.

Therefore - I don't trust that time honored method as it hasn't proven itself to be fool proof.

I'll stick with the Wing Monkey
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My interpretation of the statistics was that the problem isn't the method. But, rather the failure to consistently and correctly apply it. Wing Monkeys are pretty nifty. But, inflation is double whammy on the banana and fuel budgets.
 
Airplanes have lousy fuel gauges because pilots are cheap bastards. The senders go bad after awhile and need to be replaced. Sadly it is hugely expensive for a nominal gain in safety.
 
wilkersk said:
I don't even trust the fuel gauge in my car. I'll be damned if I'll trust one in an aircraft. The most accurate gauge involves a dipstick, a watch, and a couple of brain cells.
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How's that work for you if there's a leak/loose cap/etc? That 13gph you plan for can end up being 7gpm.
 
Like I have said many times, fuel and engines are overrated.

37373d62d49213be955d4b4543e844e1.jpg
 
Timbeck2 said:
...involve fuel starvation, and the only accuracy requirement of a fuel gauge is when it is empty, why can't someone develop a better fuel gauge to tell pilots exactly how much fuel they have left?

I'm not talking about your FADEC stuff, I'm talking about the average Joe flying his Cessna 172 or Cherokee 140 around.
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I flew as an average joe but was constantly reminded during training to always fill the tanks before flying and use a wooden dip stik to check the tanks before take off. I always, always was present during fueling and in ninety percent of the time refueled it myself. Most of running out of GaS seems to be carelessness or lousy planning . My instructor and several fbos always reminded pilots that fuel gauges were not to be trusted. So I didnt. Easy.
 
I stick my fuel before every flight and I don't trust a fuel gauge either. My point is that not only are they to be not trusted, almost every one of them that I've seen isn't even close to being accurate. That is the point of this thread. I hate to use an old quote here but; we can put a man on the moon but we can't develop a fuel gauge that is accurate at any time.
 
Shepherd said:
I've been flying most of my life.
The only planes I've ever seen with consistently accurate fuel gauges were those with sight gauges like those in the old Pa-11/12/18 Cubs, etc.
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I love that about the J5 I am currently flying it has an 18 gallon wing tank that feeds a 7 gallon header tank and both have sight gauges. You look out the window and you can see if you have gas in the wing tank once that is empty and it is in the header you know you have an hour plus reserves. I still always check just to make sure the float isn't stuck of something.

Most planes can fly on not a lot of gas longer than I care to sit in one spot or my bladder can go anyway.
 
IMHO, the best way to "know" how much fuel you have on-board is a combination of visually checking the fuel before flight, having well-maintained fuel gauges that at least generally "work" (the ones in my 50 year old Viking work reasonably well) and equipping your airplane with a well-calibrated fuel totalizer. In that scenario, you know how much fuel you had to start, you know how much you've burned, and you've got a reasonably accurate fuel gauge that can act as a "check" against the other two. A massive in-flight fuel leak isn't something I worry too much about; if the tank's leaking, it'll be leaking on the ground. As far as forgetting a fuel cap, well, I try hard not to be a dumbass :)
 
The only airplane I've ever seen with accurate fuel gauges was my old Cherokee, though those were starting to get wonky when I unloaded it. Quite a luxury, actually. Time and fuel burn have still and ever been all I trust.
 
RotorDude said:
Using a rope. But to be honest, I also drive to the airport (too long a bike ride).
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Being towed behind something with an engine and fuel, or a ground launch system? ;)
 
In Australia - the ATSB found that in 100% of GA fuel related accidents the aircraft had a bad fuel gauges. The Aussies instituted Rule 100.5 requiring periodic calibration of fuel instrumentation.

I like the pronouncement of useless, or that fuel gauges provide limited safety benefit. The last statement is opinion. There is no factual information to support that statement

Operational Fuel gauges are required equipment - So the regulation intended for safety is to have a work around for one instrument

That sounds like a Minimum Equipment List procedure is the MEL approved and how long can you use the MEL

Speaking of a Cherokee - here is the Piper Calibration limits for the fuel gauge in the Maintenance manual. Apparently the factory was looking for accurate.

So the FAA mandates working fuel gauges and the manufacturer wants accurate fuel gauges and that accuracy to be maintained throughout the life of the aircraft. The third leg of the stool seems to be a bit iffy.
 

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bradg33 said:
This is the right answer, despite people constantly repeating the totally wrong "only accurate at empty" nonsense. A lack of reading comprehension skills leads to that result.
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youze guyz disagreeing with me can't read write.

wilkersk said:
I don't even trust the fuel gauge in my car. I'll be damned if I'll trust one in an aircraft. The most accurate gauge involves a dipstick, a watch, and a couple of brain cells.
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Don't call yourself a dipstick. You're doing the right thing.
 
EdFred said:
Being towed behind something with an engine and fuel, or a ground launch system? ;)
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Either one uses fuel and and engine, of course. But so does the vehicle that gets me to the airport. The point being that once launched, no fuel or engines are needed. And I can assure you that the exhilaration of flying solo cross country from A to B on thermals only (which I did last week for the first time) is unmatched by anything. :)
 
[QUOTE=".

My Jodel has a direct-reading mechanical gauge that I built for it. Deadly accurate. But that fuselage-mounted tank is relatively deep in relation to its width and length and the float is in the center, where the variation due to sloshing is minimal. Wing tanks can't match that.[/QUOTE]
The early Jodels that I flew just had a float with a wire protruding through the filler cap, simple and effective. used the same in my hombuilt Turbulent,
 
If a high percentage of aircraft accidents... involve fuel starvation, why do so many catch fire right after the crash?
 
Timbeck2 said:
I stick my fuel before every flight and I don't trust a fuel gauge either. My point is that not only are they to be not trusted, almost every one of them that I've seen isn't even close to being accurate. That is the point of this thread. I hate to use an old quote here but; we can put a man on the moon but we can't develop a fuel gauge that is accurate at any time.
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Well the man on the moon is often used to wonder about a lot of things but important to remember, many poor souls failed to make the moon due to bad planning or equipment failure. In my case , fear prompted much of my careful fuel planning but even then I screwed up and could have easily killed myself and another person! Real dumb! landed at ocean city maryland in the early eightys, in a sundowner, filled it before I left home, went to teterboro, dropped off one, went back to ocean city, where the gas tank was surrounded by plowed Iceland snow. Afraid of a prop strike I dropped the person off, low on gas and flew 15 min to home base. Landed at dark, put plane away. It used the limit to refuel it. I could easily have run out. Just blind luck! Never did it again.
!
Timbeck2 said:
I stick my fuel before every flight and I don't trust a fuel gauge either. My point is that not only are they to be not trusted, almost every one of them that I've seen isn't even close to being accurate. That is the point of this thread. I hate to use an old quote here but; we can put a man on the moon but we can't develop a fuel gauge that is accurate at any time.
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