Don’t Blame your Fuel Gauge

"According to the Joseph T. Nall report (produced by AOPA’s Air Safety Institute), 89 accidents occurred in 2010 as a result of fuel exhaustion; 11 of them fatal. And despite a decline in fuel management accidents through 2008, more recently those numbers have been reversing, accounting for eight percent of all accidents in 2010.
According to the Nall report, inadequate flight planning — failure to determine the amount of fuel required for the flight or the amount actually on board, or to verify the rate of fuel consumption en route — accounted for the largest share (48 percent)."

This was reported below in the FAA Safety Team Briefing in October 2013 and is indented in italics:

FAASafety

Briefing - Fuel Monitoring 

October 2013

The General Aviation Joint Steering Committee

Safety Enhancement Topic of the Month

Don’t Be “Fuel-ish”

While fuel exhaustion continues to be a a top ten issue for General Aviation safety - It gets very little insight or a real root cause analysis to the factors involved.  To most in the aviation field this is a simple pilot problem with a very simple answer, But there is a hidden truth lying in the commonly held belief below:  

"One of the more head-scratching aspects of fuel management accidents is simply how easy they are to prevent, as well as recognize well before they happen.Blaming a bad fuel gauge doesn’t cut it. To help prevent getting into this situation, here are some tips:"

Note:  A fuel gauge is required equipment on all powered GA aircraft and it is supposed to be accurate throughout the range from empty to the zero fuel level.  

The FAA Safety Team implies in the paragraph above that you could be flying your aircraft with a bad fuel gauge - I hope this isn't so.

§91.7   Civil aircraft airworthiness.
(a) No person may operate a civil aircraft unless it is in an airworthy condition.
(b) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for safe flight.  The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions occur.

§23.1305   Powerplant instruments.
The following are required powerplant instruments:
(a) For all airplanes. (1) A fuel quantity indicator for each fuel tank, installed in accordance with §23.1337(b).

§23.1301 (Systems and Equipment) Function and installation.
Each item of installed equipment must—(a) Be of a kind and design appropriate to its intended function.(b) Be labeled as to its identification,function, or operating limitations, orany applicable combination of these factors;(c) Be installed according to limitations specified for that equipment; and (d) Function properly when installed.

§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)

And this is where the hidden truth lies,  and this is where I believe the  FAA Safety Team author missed the point - It is a subtle but significant difference and it should read as follows:

Flying an aircraft with a bad fuel gauge doesn't cut it 

If we review  -  I believe the accident chain starts at this point.

• After visually checking the fuel in the aircraft,  the pilot then got into the aircraft   put power onto the aircraft and observed that the fuel gauges did not report accurately how much fuel was in the tank.  

Or 

• The pilot observed on filling the aircraft that the gauges indicated the aircraft had more or less fuel than that required to fill to tabs as an example.

STOP RIGHT THERE - Take your aircraft to the nearest service center and have your required aircraft equipment repaired or replaced to make your aircraft airworthy.  

Don't fly an aircraft with bad fuel gauges - it is that simple.

If you are flying an aircraft with bad fuel gauges - you should have a ferry permit.     

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When you look at it from this perspective - yes the solution to fuel exhaustion may be just as easy as the brief author suggests.  

Simply mandate that required fuel level reporting equipment function properly when installed on the aircraft.  

I understand fuel level reporting is not good in GA - That they don't work is the universal complaint.  

If that is true, then this problem lies with the FAA Administrator -

1.) Did the FAA Administrator allow an Aircraft Type Certificate to be issued that ignored fuel level reporting requirements of FAR 23.1301, FAR 23.1305 and FAR 23.1337.

2.) Does the FAA enforce the requirement that this equipment is to function     throughout the life of the aircraft as designed above.

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Why have we turned a blind eye to fuel level equipment & why are fuel reporting systems treated in a different manner than any other required equipment on the aircraft. 

Because if we re-write the FAA Safety Brief and replace fuel level with another piece of required equipment ..... Frankly, it just sounds silly.   

"One of the more head-scratching aspects of airspeed management accidents is simply how easy they are to prevent, as well as recognize well before they happen.Blaming a bad airspeed indicator doesn’t cut it. To help prevent getting into this situation, here are some tips:"

Required equipment is required for a reason - let's make it that way.

Flying Magazine - May 2013

Flying Magazine

Well we have been waiting for this -

Recognition in the press or an editorial resulting from a flight utilizing our fuel level sending technology.

When reading about all the very significant changes made for the new 2013 G5 Cirrus.  You will see the mention of accurate fuel level - not once but three times.

In this aircraft review there is an discussion about the fuel imbalance messages being determined by fuel level.

Not the Fuel Totalizer - the Fuel Level System 

If you pay close attention -  the differential they are talking about is an accurate reading of a level of fuel at 8,  10 gallons between the two wing tanks and then at 12 gallons. 

Yes -- our senders give levels of accuracy in the 46 gallon tank of less than  two gallons.

Again in the side bar - a mention of not just accurate - but highly accurate fuel level.

I

Imagine an editorial in General Aviation magazine - praising the quality of the fuel indication.

Not Fuel Totalizer -
The Fuel gauges

And finally in the specification banner another mention of the electronic fuel level sending units.

While we strive every day to change fuel level sending in aviation with better technology, quality assembly 

and attention to detail 

We are very proud that our efforts are being recognized 

Cirrus Aircraft Fuel Level Retrofit - Video

Cirrus Aircraft Fuel Level Retrofit 

We set out to change fuel level in Aviation.  We wanted to demonstrate that accurate and reliable information on fuel quantity could be accomplished in single engine and other aircraft.

The concept has literally taken off.  

We have proven they we can measure fuel in a highly dynamic environment and we can do so accurately.   


Click Here for Cirrus Inflight Video 

Measuring Fuel ... How Do you Measure Up?

I have been trying to track down this exact "Pilot Folklore" regarding fuel level in aircraft.
  
Specifically the widespread pilot belief that the FAA doesn't require for you to have working fuel gauges in your aircraft.

The gauges only need to tell you when you're empty.

Sure enough in a FAA Safety Bulletin in April 2002
The FAA said just that - the exact words as follows:

 As you can see, the regulations only require that the aircraft fuel gauge read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply determined under 14 CFR §23.959(a).  Therefore, the gauge cannot be depended upon for checking the fuel quantity in a tank. This is especially true of the smaller, less sophisticated general aviation aircraft. Visual or physical checking or both are the only safe means of determining the actual quantity of fuel onboard such aircraft. How do you measure fuel? Do you measure up?  H. Dean Chamberlain 

In fact,  as recently as February 2013, the FAA allowed this to be reprinted in a blog site... unbelievable.   Supporting a culture where it is acceptable for "Fuel Exhaustion" to be one of the TOP 5 GA Incidents, and according to the AOPA Nall Report the second highest cause of pilot death.

In most cases pilots will blame  pilot behavior and preflight.  All pilots will rally to the aviator cause, and like this FAA article, seek to change the an obviously errant pilot procedure.   .... Education is the tool to address this serious safety issue .  Despite the efforts, the number of fuel exhaustion incidents still remain high.
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So back to the fuel gauge ....  I have been through over 150 certification meetings in my life - 

But I have not yet brought in a new aircraft or new aircraft modification and told the Administrator that; 

I removed the fuel gauge and  replaced it with an idiot light letting the pilot know -

"That at this very moment you ran out of fuel"  

or propose an aural announcement like:

 "WARNING YOUR ENGINE WILL NOW STOP... PLEASE LOOK FOR A SAFE LANDING & HAVE A NICE DAY"

But according to the FAA author above - that is exactly what the administrator is looking for in an aircraft design  ....

...   REALLY,  What pilot or aviation professional believes this?


 So what do the FAR's (Federal Airworthiness Requirements) really say:

Title  14 Code of Federal Regulations (CFR) §23.1337(b), Powerplant instruments installation.

  It reads:

(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.

It says you have to have a fuel gauge and it needs to show you the amount of fuel in your tank in flight.  It says that in fairly clear language. 

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 14 CFR §23.959(a);

It says that the fuel gauge must have the capability to be be calibrated to read zero usable fuel.  This feature is an added part (In addition) to the requirement that it must  let you know how much fuel you had in total,  when the aircraft is in flight.

Does anyone believe that the FAA would have you put a fuel gauge in an aircraft and 
let that gauge

• Indicate any value fuel level other than zero.
• When you were at zero usable fuel it will read "ZERO"

According to this skewed interpretation of the regulation.

A binary gauge meets this folklore requirement   ... 

•  "SOME FUEL"

to be followed by a calibrated  

• "NO FUEL" 

Well the FAA actually expects something dramatically MORE Accurate 

in FAA TSO C55a -

- No more than 3% of full scale tank volume in the worst case -

Minimum Performance Standard for Fuel and Oil Quantity Indicating System Components, 

When you get in your aircraft and you look at your fuel gauges.

• Do they meet the real and intended FAA standard. 

or 

• Do they just give you folklore.

CiES Fuel Sender - In the News - March 2014 Aviation Consumer

In the March 2014 Issue of Aviation Consumer the CiES Cirrus Fuel System Retrofit is reviewed.

As we have talked about in previous blog posts - Cirrus G1 / G2 retrofits are a challenge.  The results and review were favorable and represent what can be obtained on the early series aircraft.   Later model Cirrus G3's can achieve nearly perfect results.

Please look to 

aviationconsumer.com

for more information and other informative articles

Indian Engineering Students Recognize the Significance of Magnetic Field Fuel Level Sensing

As I was doing presentation research a potential automotive client and I ran across an undergraduate paper in engineering that listed our technology as a system to utilize for fuel level measurement on engineering project cars - complete with a picture of our aviation sensor system.

I was encouraged  -  The next generation of engineers seem to easily embrace the difference and improvement  AMR sensing provides to fuel level.

Fuel Level Paper

Every day in the lab and every day aircraft owners see the benefits that accurate fuel level provides, and shake our heads at the level of accuracy we have become used to in our cars.

In preparing my meeting notes,  I made the realization that the current resistive technology has remained unchanged in our gas or diesel vehicles for 85 years.

It is probably the only system that a pioneering automotive engineer of the early 20th century would recognize and understand on a modern automobile


The carburetor left current production cars in 1990 and in light trucks in 1994.

It's time to throw the old potentiometer fuel level  to the curb.

Aircraft Fuel Gauge Accuracy

Fuel Sensor Accuracy 

The following quoted from reference 2.

This FAR Part 91.205 fuel-gauge requirement can be seen as a corollary of a more general and more fundamental point, namely the importance of taking a layered approach to safety.

For any important task, you want to have multiple independent ways of dealing with the task, so that each way can serve as a cross-check and a backup for the other(s).

For example, the right magneto is a backup for the left magneto.  Similarly, pilots are trained to never overemphasize or underemphasize any particular instrument, but rather to scan all the instruments, cross-check them, and use all available information to build an understanding of the overall situation.

When we apply this idea to fuel, it means you should have multiple independent sources of information about the fuel quantity. 

Good sources include:

• The preflight measurement in combination with an estimate of the fuel-burn rate and the elapsed time.

• A fuel totalizer or totalizer function on the MFD.

• The fuel level gauges and by corollary the fuel level sensors

No one source should be overemphasized at the expense of the others.

Remember that having two magnetos doesn’t just make the engine twice as reliable; it makes it thousands of times more reliable.

Using gauges as a backup to a visual preflight, flight planning and totalizer makes fuel exhaustion vastly more unlikely.

CiES Inc builds accurate and reliable fuel level sensors - 

References

1.

“Pilot-In-Command Decisionmaking” (Chapter 21 of See How It Flies) http://www.av8n.com/how/htm/decision.html

2.

"Aircraft Fuel Gauge Accuracy" http://www.av8n.com/fly/fuel-gauges.htm