If a high percentage of aircraft accidents...

[wanttaja]

I would like to see better fuel gauges, but they still won't prevent fuel exhaustion. That's my point. There are far too many examples of guys pushing on when they could have stopped for fuel but didn't, and they knew they were low on fuel.

Concur with Dan, here. I've read ~4,000 accident reports in my analyses, and there were few "surprise" fuel exhaustion cases. Almost all of them knew they were low on fuel. Saddest were those who passed an airport because the next one had cheaper fuel....

Having a definitive, by-God meter that says you will be a glider in 6.3 minutes only makes a difference if the pilot is willing to believe it...and it's completely accurate, down the point where it anticipates the pilot's changes in throttle. Otherwise, some pilots will STILL exhibit the same unwarranted optimism they do now...

My airplane has an antiquated, corroded and non (well, BARELY) functional required fuel quantity instrumentation (steel wire floating on a cork in my line of sight). I just make sure there's always gas in the tank. Came close to running out once, and it WASN'T the fault of the gauge. 14 gallons into a 16 gallon tank, forsooth.

Ron "knees still a bit weak" Wanttaja

 

[Scott Philiben]

Dan: Well, float base rheostats are for the most part gone from new aircraft production. I know, it is news to most people.
New floats by the way are either closed cell foam - NBR or Epoxy with Microballoons - They are very difficult to fuel soak - we have tried
Most new fuel quantity systems are digital.

I read the NTSB reports as well so I can fore see what somebody might do wrong and work a method to prevent occurrence.

My point and yours as well is that if an instrument is in the aircraft, it is there for a purpose
and it should be functional. So functional gets a very wide berth with fuel level gauging in aircraft. There is a huge contrast in that what we would expect from a
Tachometer vs the fuel gauge - neither has an accuracy standard posted in the FARS (some have accuracy standards in the MM)
but no-one would say that the Tachometer should only be accurate at zero, as it makes no sense for aircraft instrumentation.

Instrumentation should work the same in the aircraft as on a flight simulator - the geeks that design software get it - as you point out some pilots ..... don't

We build fuel quantity systems for both Cirrus and Textron - for AVGAS and Jet A

The fuel gauge is there to provide adequate warning of a lowering fuel state, reaching a lower fuel level than planned enroute or most importantly it is required to be there to tell you that you are out of fuel options and should declare a fuel emergency. A low fuel warning light has been part of Cessna since the re-start and has statistically prevented accidents in aircraft produced since the re-start (FAA Publication) Modern systems warn of fuel imbalance and some are utilized to select tanks automatically.

I appreciate the position of training - but 37% of fuel starvation events occur in cruise flight, which is a "I don't really have a clue how much fuel I started with" proposition combined with the 44% professional pilot statistic - yes new pilots make mistakes - but this appears to be a bold pilot mistake

I don't really care how dumbstruck the pilot is by this fact - but for the good of all aviation - all pilots should find a runway to land on if only to save fields and roads for cars and cows.

 

[Dan Thomas]

My point and yours as well is that if an instrument is in the aircraft, it is there for a purpose
and it should be functional. So functional gets a very wide berth with fuel level gauging in aircraft. There is a huge contrast in that what we would expect from a
Tachometer vs the fuel gauge - neither has an accuracy standard posted in the FARS (some have accuracy standards in the MM)
but no-one would say that the Tachometer should only be accurate at zero, as it makes no sense for aircraft instrumentation.



I appreciate the position of training - but 37% of fuel starvation events occur in cruise flight, which is a "I don't really have a clue how much fuel I started with" proposition combined with the 44% professional pilot statistic - yes new pilots make mistakes - but this appears to be a bold pilot mistake

I don't really care how dumbstruck the pilot is by this fact - but for the good of all aviation - all pilots should find a runway to land on if only to save fields and roads for cars and cows.

In Canada we have a legal limit to tachometer accuracy. +/-4%, measured in the middle of the cruise RPM range. I don't know why the FARs don't have an equivalent. Magnetic drag type tachs usually start to under-read as the magnet ages and weakens, and presents the possibility of sustained propeller overspeed, a dangerous condition since the centripetal forces on the prop increase by the square of increase in RPM. The law applies to those old mag-drag tachs, and I encourage owners to switch to digital tachs that don't suffer that inaccuracy, nor do they need a flexible tach cable that eventually gets sticky and makes the tach needle wobble. The STC'd digital tachs cost no more than a new OEM tach with the correct (and required) green/yellow arcs and redline applied.

It's easy to figure the 37 PPL vs. 44% CPL fuel-starvation difference. A PPL is more likely to fill the tanks far beyond the need for the proposed flight, just like he did as a student. He feels safer that way. The CPL is trying to maximize payload and takes the calculated fuel plus reserve, and if he's IFR he has to have fuel to the alternate, too. FOr most flights, that's less than full tanks, and sometimes unforeseen circumstances eat into his reserves to the point that he's down to dry tanks. He feels pressure to complete the flight and so doesn;t turn back when he should have, or didn't land enroute for fuel. The professional is under WAY more pressure than the recreational flyer, and so some types of accidents are more common in the commercial world.

Conversely, the PPL is often the guy who will continue VFR into IMC without IFR training, and in spite of all the fancy intruments in front of him, all telling him the truth, he loses control and crashes because he can't make sense of the information. That's a training problem, partly, but more of an attitude problem; he knew better than to poke into the scud but did it anyway. The same attitude in the guy that takes off without dipping his tanks or doing any other preflight stuff.

And I know that fuel floats are epoxy foams or whatever now instead of hollow brass shells soldered together. I see those floats on new senders. Carburetor floats have also switched from soldered brass shells to polymer floats, and those floats have sometimes come apart in the carb and caused engine failures. That makes some folks distrustful of plastic stuff, even though epoxy is better, and will stay better, than brass. But not everything is epoxy. Here's an SB on those floats: http://www.kellyaerospace.com/service_pdf/SL_029_brass_float_s.pdf

Some GA airplanes have annunciators to indicate things like low vacuum or low fuel and so on. The trouble is the fuel sloshing around in turbulence and making the float dive far enough to make the light flash, alarming the pilot unduly. I have spent time chasing that sort of thing and because there's no damping circuitry to average out the fluctuations and arrive at the correct indication, those spurious flashes will continue and sooner or later the pilot starts ignoring the light altogether.

 

[Sundancer]

POA is certainly a forum for folks who want to prevent the "other guy" from making a dumb mistake. . .there isn't a problem here to solve - pilots aren't turning powered planes into gliders because the fuel gauges are sketchy. . .

 

[wanttaja]

Maybe Wanttaja could tell us what percentage of various models are still in service. It would be interesting to know how many Cessna 172s, of all those built, are still flying.

No one can tell you how many are flying. But a comparison with the Deregistered list might be able to give us some bit of insight.

Using my January 2016 copy of the FAA registration database, I determined how many of certain aircraft types were on the registry. I then compared it to the number of the same type of aircraft were listed in the Deregistration table, and NOT listed as "Exported". Then the number of active aircraft is divided by the sum of active and deregistered to produce the "% Active" value.

Aircraft__________Active____Dereg___% Active
Diamond DA-40_____747______14_____98.1%
Cirrus____________4536_____141_____96.9%
Diamond DA-20_____362______52_____87.4%
Cessna 182_______14408____3683_____79.6%
Piper PA-28-181____2423_____719_____77.1%
Piper PA-18________3890____1186_____76.6%
Beech Bonanza_____10686____3365_____76% (Models 33, 35, or 36)
Cessna 172________22329_____7918_____73.8%
Piper J-3___________4620_____2488_____64.9%
Cessna 210_________4109_____2394_____63.1%
Cessna 150_________9825_____6979_____58.4%
Cessna 152_________2236_____2322_____49%

(Is there an easy way to build tables on POA?)

As once might expect, the more-recent models have a greater percentage of aircraft on the active registry. As a reminder, note that being on the "Active Registry" doesn't mean the plane is flying. Just that the owner is renewing his registration every three years.

What was surprising was the number of examples of each type of aircraft that were exported:

Diamond DA-40_____99
Cirrus____________1155
Diamond DA-20_____339
Cessna 182________3199
Piper PA-28-181 ____651
Piper PA-18_________583
Beech Bonanza_____952
Cessna 172_________6400
Piper J-3___________307
Cessna 210_________1991
Cessna 150_________1805
Cessna 152_________1704

Ron Wanttaja

 

[Kritchlow]

I read here about people bragging they can beat airliners on a trip. When they break down their times there's virtually zero time spent on flight planning. In theory, with good planning, gauges wouldn't even be needed. Of course they are required and are a useful tool, but I think too many guys want to rely on them instead of planning.

Many people here laugh at the airlines because all the planning is handed to the crew. That said, every fuel burn/remaining at every checkpoint is posted. Even if the gauges and flows take a dump after takeoff, we know proper planning has been done.

 

[wanttaja]

Actually, IIRC, the fatality rate for fuel exhaustion accidents is kinda low. All they have to do is land, the same thing they do after every flight. It's just no longer at the pilot's discretion.....

Some random aircraft types that I had analysis data for:

(First number is the percentage of all accidents that were fatal, the second is the percentage of Fuel Exhaustion accidents that were fatal)

Piper Cherokee 140,161,180, and 181: Overall 19.4% vs. 12.0%
Cessna 172: 13.1% vs. 5.6%
Cessna 210: 23.2% vs. 6.1%
All homebuilts: 25.4% vs. 13.9%.

Cirrus results were interesting: it was 32.2% vs. 25.0%, but there were only four fuel-exhaustion accidents in my database. Good chance it's due to superior fuel management aids.

Ron Wanttaja

 

[asicer]

Cirrus results were interesting: it was 32.2% vs. 25.0%, but there were only four fuel-exhaustion accidents in my database. Good chance it's due to superior fuel management aids.

Do you have any DA20/DA40 data? Off the top of my head, that's the only other part 23 piston single designed in the same era as Cirrus.

 

[wanttaja]

Do you have any DA20/DA40 data? Off the top of my head, that's the only other part 23 piston single designed in the same era as Cirrus.

Haven't looked at them in any detail yet. Ran a search on DA40s, got 28 accidents with 9 fatalities for 32% fatality rate. Skimmed the Narratives, no apparent fuel exhaustion or starvation cases. Relatively low number of samples, though...I usually want to see at least 50 accidents before starting to draw conclusions.

Ron Wanttaja

 

[Kritchlow]

Okay, tons of nice numbers.

Any chance of a summary conclusion??

 

[wanttaja]

Okay, tons of nice numbers.

Any chance of a summary conclusion??

1. It varies by aircraft type, but on the whole, Fuel Exhaustion accounts for less that 10% of General Aviation accidents. The single most-common type, the Cessna 172, sees, on the average, just six fuel-exhaustion accidents per year.

2. Fuel Exhaustion accidents tend to not be fatal, with the fatality rate due to Fuel Exhaustion for some types being almost half those of their overall fatality rate.

3. Modern fuel management systems appear to help... the Cirrus' Fuel Exhaustion rate is about 1/3rd that the Cessna 172 (though pilots involved in Cirrus accidents have, roughly, 500 hours' more experience).

My own conclusions:

1. I do not agree with the reference to Fuel Exhaustion being the cause of a "High Percentage of Aircraft Accidents".
2. I am of the opinion that mandating improved fuel-management systems for existing GA aircraft would not be cost-effective, due to the complexity of the STC process vs. the actual numbers of accidents that might be prevented.

(Edit: Left "not" out of the sentence....)

3. The two main types of implementers would be A) Safety-conscious pilots who would be less-likely to have a fuel-exhaustion accident anyway, and 2) Pilots who will use the system to shave margins tighter. Hence, making such systems available for optional installation would be of limited value.
4. Ensuring such systems are present in new-production aircraft seems a worthy goal.

Ron Wanttaja

 

[Dan Thomas]

Thanks for the research, Ron. Very interesting.

The larger numbers of deregistered 150s, 152s and 172s is at least partly due to their popularity as trainers. They get banged up more often and accumulate hours at a rapid rate. I have encountered 172s with more than 20,000 hours on them. Hardly worth rebuilding such airplanes, with just about everything worn out and cracks developing everywhere.

Exports to Canada will be a significant portion of overall exports. We have a tenth of the US population, with a roughly equal percentage of pilots, and airplanes are regularly imported when our dollar is strong, and they tend to go back to the US when it's weak (like it is now). The rising costs of import and export might be slowing that somewhat.

 

[Scott Philiben]

POA is certainly a forum for folks who want to prevent the "other guy" from making a dumb mistake. . .there isn't a problem here to solve - pilots aren't turning powered planes into gliders because the fuel gauges are sketchy. . .

Interesting Comment -

So if I get this right your expressed and admittedly common logic is:

• Fuel gauges are sketchy in GA aircraft.
• Non functional REQUIRED gauges meant to warn a pilot of a condition will not work to warn a pilot of the condition.

The logic above suggests that you have not flown an aircraft with functional fuel gauges
Because on the face of it - It doesn't make sense. That would be a very sad state of affairs.

Do fuel gauges and low fuel warnings in cars, warn of the potential for fuel starvation - I believe that is a YES
- I asked a random group of people (non pilots) outside the office and they said YES

Maybe we should post a random survey

I happen to have friends with cars that use sticks as fuel gauges - 1950's MG's and VW (Picture below)
They report that they adhere to a set odometer reading and suffer occasional fuel starvation.
Yes I know the differences - but a 30hp VW in modern traffic is as close to an aircraft operational parameter as you are going to get
So fuel gauges we can agree are an assistance to drivers in automobiles.



Do other aircraft gauges warn of conditions we should as pilots be aware of - I believe that is a YES
Do other gauges prevent operation outside of required parameters - I believe that is a NO
Do pilots ignore gauges and operate outside parameters of safe flight - YES I think we can all agree on that

There are two things we need for powered flight:

• Airspeed - Rely on indication (Trust but verify)
• Fuel (????)

I believe relying on a fuel stick is anachronistic - and has more to do with a ritual, than safe practice, as you can't stick the tank in flight.
It is the relative equivalent of looking at the prop visual rotational characteristics on the ground - and using them in flight. If Tachometers in aircraft were sketchy - that is what we would have to do. We would create a work-around. Similar to what we do with fuel quantity.

What is interesting is that there is data to say that the common logic is wrong.

As for the Canadian reference - I am seriously thinking on that, there is a measure of boldness as I stated

As for measuring fuel - If we can remove static from radios (Digital Communication) and spurious satellite signals (Digital GPS)
Sloshing fuel is not really an issue - actually unless you have some pretty severe turbulence - the fuel is quite stable in an aircraft tank
I have 100's of Garmin data plots to show that

 

[Scott Philiben]

Haven't looked at them in any detail yet. Ran a search on DA40s, got 28 accidents with 9 fatalities for 32% fatality rate. Skimmed the Narratives, no apparent fuel exhaustion or starvation cases. Relatively low number of samples, though...I usually want to see at least 50 accidents before starting to draw conclusions.

Ron Wanttaja

the DA-40 numbers will be interesting as they have utilized a capacitive system that, when new, I have been told, provides good fuel level indication

 

[Sundancer]

Interesting Comment -

So if I get this right your expressed and admittedly common logic is:

• Fuel gauges are sketchy in GA aircraft.
• Non functional REQUIRED gauges meant to warn a pilot of a condition will not work to warn a pilot of the condition.

The logic above suggests that you have not flown an aircraft with functional fuel gauges
Because on the face of it - It doesn't make sense. That would be a very sad state of affairs.

Do fuel gauges and low fuel warnings in cars, warn of the potential for fuel starvation - I believe that is a YES
- I asked a random group of people (non pilots) outside the office and they said YES

Maybe we should post a random survey

I happen to have friends with cars that use sticks as fuel gauges - 1950's MG's and VW (Picture below)
They report that they adhere to a set odometer reading and suffer occasional fuel starvation.
Yes I know the differences - but a 30hp VW in modern traffic is as close to an aircraft operational parameter as you are going to get
So fuel gauges we can agree are an assistance to drivers in automobiles.

View attachment 47154

Do other aircraft gauges warn of conditions we should as pilots be aware of - I believe that is a YES
Do other gauges prevent operation outside of required parameters - I believe that is a NO
Do pilots ignore gauges and operate outside parameters of safe flight - YES I think we can all agree on that

There are two things we need for powered flight:

• Airspeed - Rely on indication (Trust but verify)
• Fuel (????)

I believe relying on a fuel stick is anachronistic - and has more to do with a ritual, than safe practice, as you can't stick the tank in flight.
It is the relative equivalent of looking at the prop visual rotational characteristics on the ground - and using them in flight. If Tachometers in aircraft were sketchy - that is what we would have to do. We would create a work-around. Similar to what we do with fuel quantity.

What is interesting is that there is data to say that the common logic is wrong.

As for the Canadian reference - I am seriously thinking on that, there is a measure of boldness as I stated

As for measuring fuel - If we can remove static from radios (Digital Communication) and spurious satellite signals (Digital GPS)
Sloshing fuel is not really an issue - actually unless you have some pretty severe turbulence - the fuel is quite stable in an aircraft tank
I have 100's of Garmin data plots to show that

You drew a lot of conclusions from me saying it's just not a problem. My airplane doesn't warn me of worn brakes pads, popped flap track rivets, or failing hoses, either. I sort of expect to catch that stuff at preflight, 100 hour, or annual.

We have a JPI Fuel Scan; I dip the tanks, input the total, and the JPI measures the fuel flow, talks to the GPS, computes required, used, remaining, etc. I accept the risk of fat fingering the starting quantity, or a leak in the system upstream of the fuel flow measuring point.

But before the JPI, I dipped the tanks, too. And estimated burn rate based on power settings, plus a safety factor. I don't think I'd modify that behaviour with the addition of hyper-accurate fuel gauges, honestly. The value added isn't there, to my reasoning, not enough for the added complexity, cost, etc. For a simple airplane, you'll have a very good idea of the endurance; subtract an hour, be on the ground then.

I admit the JPI allows us to fly closer to the reserve limit - we've found it to be spot on, often less than a gallon off. You could argue the JPI meets your super-accurate fuel gauge requirement. But, it's not cheap, requires maintenance, and if it went away, it really wouldn't affect my flying in a substantial way. I can't say I've really used the factory fuel gauges in flight for any real meningful decision making. Not because they're broke (they aren't), but because I have better sources (the clock, knowing the power settings, and how much I started with.

 

[Scott Philiben]

As a manufacturer proposed exactly what you are saying - What does super accurate mean to you (Within 5, 2, 1, 0.5 gallons)

FAA Advisory Circular 23.17 (underlines are mine)

2. BACKGROUND

1. Recently there has been a trend toward replacing fuel pressure indicators and analog reading fuel flowmeters with digital fuel flowmeters/fuel totalizers. Developments in microprocessor technology have resulted in digital fuel flow computer systems that are economical, accurate, and that provide data for improved fuel management. These digital fuel flow computer systems also have features for displaying total fuel consumed, total fuel remaining, and time remaining. The accuracy of these readings is dependent on the initial fuel supply entered into the fuel computer. The precise digital readings that are displayed to the nearest tenth of a gallon could give a pilot a false sense of accuracy and security, especially the readings for total fuel remaining and time remaining.
   

Digital fuel flowmeters are not a required powerplant instrument except for turbine engine airplanes with an Amendment 23-43 certification basis. They are optional equipment and should not be considered replacements for fuel quantity or fuel pressure indicators. Different interpretations of the regulations have caused conflict and lack of national standardization on installation of fuel pressure indicators and fuel flowmeters/fuel totalizers in small airplanes that have continuous-flow, fuel-injection systems in reciprocating engines. Inquiries from members of the aviation community and manufacturers have indicated a need for information on approval and installation of digital fuel flowmeters/fuel totalizers. The location of the fuel flow transducer in the fuel system is critical for measuring the total fuel flow consumed by the engine and maintaining engine performance. Each type of installation has an impact on the operation of the fuel system and needs to be evaluated and approved.

(2) Digital fuel flow computer systems have a fuel flow transducer that directly measures the fuel being fed to the engine. The fuel flow transducer may be a small paddle wheel, an impeller, or spring-loaded movable vanes. Digital displays with a fuel computer also allow these instruments to display total fuel consumed, total fuel remaining, and time remaining at the present fuel flow rate for fuel management. Overall accuracy for fuel remaining and time remaining readings depends on the transducer processing unit and display. The largest possible error is the initial fuel supply, which is entered by the pilot at the start of each flight. Errors in the initial fuel supply may be caused by an uneven ramp, unusual loading, volume changes of the fuel because of temperature variations, malfunctions in the fuel system such as leaks, siphoning actions, collapsed bladders, and other factors. So, total fuel remaining should be verified with the fuel quantity indicator. According to § 23.1337(b)(1), fuel quantity indicators are required to be calibrated to read "zero" during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply. Therefore, fuel quantity indicators should be used as the primary fuel-remaining instruments. Fuel quantity indicators that are inaccurate should be periodically calibrated, repaired, or replaced, as necessary, to ensure reliable readings.
​

There you go - that is the official FAA wording on the subject.

Back to the point about work arounds
If Tachometers were sketchy - we would all put non-approved visual tachometers in the aircraft and say we were good to go
we might even wax on about their accuracy.



"My airplane doesn't warn me of worn brakes pads, popped flap track rivets, or failing hoses, either."

I will have to review my TOMATO FLAMES memory aid - but that is my point - trivialization of a required instrument of flight.

Given the nature of aircraft landing gear compliance, moment arm of the fuel CG in relation to the gear, uneven ramp, variances in fuel delivery indication tolerances, and fuel loading practices - being within a gallon is a pretty big deal. I fueled aircraft as a kid - I prided myself on putting in exactly what the pilot asked for and I was good at it, I could be within less than a gallon if you challenged me.

Unless it is a Piper Cherokee - that was a take it or leave it proposition

 

[denverpilot]

What was surprising was the number of examples of each type of aircraft that were exported:

Diamond DA-40_____99
Cirrus____________1155
Diamond DA-20_____339
Cessna 182________3199
Piper PA-28-181 ____651
Piper PA-18_________583
Beech Bonanza_____952
Cessna 172_________6400
Piper J-3___________307
Cessna 210_________1991
Cessna 150_________1805
Cessna 152_________1704

Ron Wanttaja

A friend's kid sold his 150 to someone who was going to crate it up and ship it to Australia a few years ago. Got a better price than any offers he had on it here. Basically they bought it nearly sight-unseen for his asking price. All he had to do was fly it to California for the buyer.

 

[Dan Thomas]

Interesting Comment -

So if I get this right your expressed and admittedly common logic is:

• Fuel gauges are sketchy in GA aircraft.
• Non functional REQUIRED gauges meant to warn a pilot of a condition will not work to warn a pilot of the condition.

The logic above suggests that you have not flown an aircraft with functional fuel gauges
Because on the face of it - It doesn't make sense. That would be a very sad state of affairs.



Do pilots ignore gauges and operate outside parameters of safe flight - YES I think we can all agree on that


I believe relying on a fuel stick is anachronistic - and has more to do with a ritual, than safe practice, as you can't stick the tank in flight.

What is interesting is that there is data to say that the common logic is wrong.

As for measuring fuel - If we can remove static from radios (Digital Communication) and spurious satellite signals (Digital GPS)
Sloshing fuel is not really an issue - actually unless you have some pretty severe turbulence - the fuel is quite stable in an aircraft tank
I have 100's of Garmin data plots to show that

Now you're putting words into our mouths, telling us that we say we fly with dead fuel gauges. Way back in post #9 I pasted the FARs that said this:

§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);

Therefore, any pilot who flies an airplane with a dead fuel gauge is in contravention of the FARs, the same as breaking any other regulation. We're not in the habit of doing that. That's why we were discussing repairing fuel gauges. There are some pilots who operate outside the law, of course, and some of them die. That's what most laws are for. Protection. Getting them to buy new digital fuel gauges won't change their behavior.

Those that dont dip their tanks are placing way too much faith in gauges of any sort. Even airliners have mechanical, visual methods of checking the actual fuel level on board.

Garmin's fuel indications are computerized readouts and averaging out a sloshing fuel reading is easy. Older, analog systems don't do that. And fuel DOES slosh around in flight; any pilot who has flown mechanical gauges knows that. Are you a pilot?

 

[Sundancer]

As a manufacturer proposed exactly what you are saying - What does super accurate mean to you (Within 5, 2, 1, 0.5 gallons)

FAA Advisory Circular 23.17

​

There you go - that is the official FAA wording on the subject.

You need to pick a more credible source. . .certainly something better than "someone may make a boo-boo and mislead themselves". The FAA publishes some good stuff. And some nonsense, too.

I think we're just talking past each other - for my purposes, the accuracy of fuel gauges isn't important; in my simple fixed gear airplane, with two easy to confirm tanks, and a clock, I'm good. Because the FAA requires fuel gauges isn't compelling enough to expend a lot of resources on making them particularly more accurate. It is important to seperate the trivial from the essential, something the Feds are notoriously poor at doing. I'd miss the oil temp and pressure indications a heck of a lot more, for example. I'm real fond of the altimeter, too. I just don't see an issue here. . .

But, just my opinion, I could be wrong. . .

 

[asicer]

Do fuel gauges and low fuel warnings in cars, warn of the potential for fuel starvation - I believe that is a YES

I guess you don't believe in the theory of risk compensation?

 

[Scott Philiben]

There is an element of risk compensation - the $100 dollar burger pilot who only flies solo and with full tanks may never need fuel gauges unless the fuel cap loses an o-ring or a isn't secured properly.
but because that is a possibility the NTSB record indicates some burger pilots run out of fuel.

All aircraft instrumentation should be functional - and required instrumentation should operate like it does on a flight simulator. Yes Dan we agree.

Analog gauges have damping built in - it takes a period of time for a magnetic field to grow or shrink or for a bi-metallic to warm up or cool - Garmin didn't invent stable instrumentation. While new digital instrumentation is nice - analog can be made to function correctly.

This by the way is not a functional fuel gauge.

This is the maintenance manual for a Piper PA-28, This provides an indication of how accurate the fuel gauge should be.
I have more references other than the FAA on what constitutes a fuctional fuel gauge



Interesting that there are manufacturer published standards for fuel gauge accuracy. This is a maintenance action for an analog device in the tank and in the cockpit.

-------------------------------------------------------------------------
Airliners have drip-sticks - Yes very true

If the redundant fuel quantity system fails in one wing on a commercial aircraft - the aircraft may dispatch with the use of drip sticks
Both wing redundant systems cannot have failed, basically 2 out of 4 systems have now failed for the drip sticks to be utilized.

The use of dipsticks is a FAA Approved Minimum Equipment List for temporary operation only. It is not a standard procedure for Part 121 operation.

A GA pilot relying on a stick as a fuel gauge to dispatch on a VFR or IFR flight.

That pilot is utilizing an un-approved FAA MEL procedure of his or her own making. While I hear that FAA FSDO personnel report this to be OK - by regulation it is not.

Remember that the GIMLI glider relied on drip sticks for dispatch as all 4 fuel quantity systems had failed - curiously dripsticks marked in Liters