Cessna 206 - CiES Bladder Tank Fuel Senders

CiES Magnetic Field Fuel Senders for Cessna 206

We continue to add configurations to the CiES Fuel Sender Aircraft list. 

Today we completed the physical elements of the Cessna 206 Bladder Senders

In the picture you will see the new machined and red  anodized senders bracketed by the senders our customer  removed for the aircraft. 

This set of senders is for the Cessna 206 bladder tank fuel system.  The old sender on the right is a FAA PMA replacement and the one on the left is the factory Leigh Sender that this Cessna 206 Left the factory with.

As our sender design simplifies the mechanics of the float sensor  This is due to the increased travel range that our magnetic field senders allow. 

This simplified design may also be applicable to Cessna 182 and 172 Bladder tanks 

We have a set of 182 Fuel Senders from a bladder tank coming our way to confirm our belief.    

Beech Bonanza Fuel Level Senders

Beech Bonanza Fuel Level 

CiES is rapidly expanding the number of aircraft that can utilize our Fuel Level Sender technology.   Today we delivered the first set of Beech Bonanza / Debonair fuel level senders.   

This set replaces the Beech original equipment Leigh senders still found in the aircraft.   The old senders had long ago given up on providing accurate fuel level. 

These new fuel level sender utilize non contact, wear free magnetic field technology to locate the float in the tank.  The technology found in CiES Senders is similar to that in your cell phone for it's compass operation.  But instead of pointing North in the compass example, the sensor in the CiES Sender points to the float and to an accuracy less than a 1/4 of a degree.  It does this accurately and repeatably.  You trust your compass to always point North - you'll trust this sender to always tell you how much fuel is in the tank.

The old rusty senders depicted in the pictures utilized continuous wearing potentiometers typically found in legacy General Aviation fuel tanks.  

Potentiometer senders have an in aircraft life of approx. 10 to 12 years before replacement or rebuild.  

You should'nt fly with fuel level senders that are 30 to 40 years past their functional life, Now you don't have to 

Beechcraft Bonanza Fuel Level Senders

We just completed our first set of Beechcraft Bonanza Fuel Level Senders


These magnetic field senders are for Tip tanks produced by a popular Beechcraft modification facility.

We are starting to branch out into multiple applications in the aviation field with our magnetic field fuel level senders, from turboprop, helicopter or piston aircraft. 

Our technology allows for a nearly plug and play solution for legacy resistive fuel level sender installations.

What started as a Cirrus Aircraft only application for fuel level sensing is slowly starting to spread across the aviation field.  With over 10,000 senders produced to date,  CiES is "The Word" in aviation fuel level sensing.

Ask us about your application? 

Cardinal Flyers Organization Digest - Sun & Fun

FROM THE Cardinal Flyers Organization DIGEST 

JP Instruments, the engine monitor folks, shared that they continue to work with CIES, a friend of CFO's, who have introduced a superior design fuel level transmitter.

JPI EDM 930

The JPI930 certified engine instrument replacement already works with the CIES transmitter in native mode, frequency domain.

JPI EDM 900

The JPI900 certified engine instrument replacement works with the CIES transmitter in voltage or current mode.

CiES Inc 177 Fuel Senders 

Several Cardinal owners have already ordered the CIES transmitters to improve repeatability and accuracy of their fuel level measurements, while reducing installation cost and fuss, and hopefully achieving longer term reliability.

www.jpinstruments.com

www.ciescorp.net

Cessna Cardinal 177 & 177 RG Fuel Level Sensor

Well we produced another configuration of our fuel level sender for a very popular Cessna Aircraft model with a rabid and enthusiastic following.

---- Yes the Cessna Cardinal 177 ----

We had sought out common aviation fuel level sensors to copy into our format and we had a few mixed results, for example owners of Cessna 177's would send in the sensors per our request,  but the part numbers of the units supplied only matched up to another model Cessna Aircraft and did not match any of the Cessna Fuel Level drawings we have on hand.  

Finally, last year we got what we were looking for - Senders from an aircraft that matched the P/N for the aircraft. 

Note:  When you get involved in this small segment of aviation - It becomes very clear why fuel level in aviation has a very low reputation.

A Cardinal Aircraft owner tells a better story: 

Anyway, I saw the mention of CiES on one of the Cardinal Flyers Digests and gave them a call.  I spoke with Scott Philiben, who said that they could build them for me, and it would interface correctly with the JPI.  JPI confirmed this.  This was last FEB 2014 when I initially purchased the JPI, based on that answer.  

I had to wait till July 1 to start install, both due to the cold weather here, and because that was my annual date  (I also wanted to install an Oilamatic Pre-oiler and an Alpha Systems AOA Gauge).  

What Scott didn't tell me initially, was that I was to be the guinea pig for them getting a TSO sender for Cardinals as this minor variation needed to be sent to the FAA and approved - they had predicted an October delivery.

Scott & company finally came thru with fully TSO'd senders in late Nov, but I then encountered the passing of my Mom, which has led to further down time - anyway, FINALLY got the senders installed last Saturday.

CiES Above - Competitor Below

I was quite impressed on the substantial difference internally between CiES senders and the Electronics International ones.  The electronics in CiES look great, and based on the digital freq meter I have, they work VERY smoothly. I am also impressed with the machining on the fuel senders.

For JPI's part, their wire harness to the wing has three wires - +5V, Ground, and Signal. The JPI diagram says NOT to connect the +5V for CiES, but what they didnt say, and I didnt know until early Nov (when I mentioned that to Scott at CiES) is that the CiES units need +12V!! Turned out not to be an issue - the JPI harness has a "Y" connection in the harness shortly after the harness leaves the JPI box enroute to the wings - I unpinned the +5 wire that comes from the JPI and capped it off, and instead ran a +12 supply from one of the Circuit Breakers (dont remember which at the moment) into the same pin spot. (There is NO interface box as there is with some other senders. Not sure if my JPI is any different internally - JPI could answer though.) Works great (again, on my digital freq meter out at the sender)

One thing I particularly like about the CiES is that the float arm wire is 3x as thick as the one from Cessna, BUT the CiES float arm easily disconnects from the sender, making installation MUCH MUCH MUCH easier. I placed a long tie wrap on the fuel sender arm (in case I dropped the float/arm combination into the tank while working the sender into position) and then after the sender was connected and small cotter pin inserted, the tie wrap was removed. The senders come with a new rubber gasket, and there is no chance of leakage in the middle (like Cessna supplied Rochester, Stewart Warner, or Leigh senders) as there is no pass-thru screw terminal.  CiES uses a 3-pin connector with a twist lock shield. VERY easy to plug in.

At first, Scott and his engineers were concerned about MIN/MAX settings, but they had an epiphany one night and realized that all measurements are relative. They were worried about setting hard "stops" these are the little metal tabs on Cessna original equipment fuel senders that limit the float arm travel.   Turns out the CIES senders have the capability to move thru-out an almost 180 degree range from straight down to straight up.  The original equipment Cessna fuel sender contained a 60 degree potentiometer which limited the angle range allowed by these senders.   The calibration in the JPI is what establishes the fuel level limits and the physical limits of the fuel tank are the physical limits of the sender.

Scott Philiben's phone number is 541-408-1095 - they are in Oregon, so there is a 3hr time difference for me. His email is scott.philiben@ciescorp.com I still have the prototype sender/float combination that we used for testing and verification that this new simpler configuration would not hit any internal ribs/structure. Can't see internally, but externally it looks exactly like the ones with the TSO labels on them!

Update - Installed and calibrated - first impressions are good 

Video of the Cirrus SR22 Retrofit

Post by CirrusPilot.

New Advertisement - Cirrus SR22 Retrofit

Parody on a Recent AOA Advertisement

Fuel Gauge INOP for initial CFI Check Ride

A Posting from Pilot Instructor Forum 

Hi all,

I am taking my initial CFI check ride this weekend. I went out to fly the airplane (C-R182) from the right seat to practice some maneuvers before the check ride. But, I realized the left fuel gauge is indicating zero no matter how much fuel is in the tank.

It sounds to me like the issue is somewhat controversial. I've heard "fuel guages only need to be accurate when the tank is are empty" and I've also heard that per 14 CFR 91.205 (b) 9 the airplane needs to be equipped with an operable "Fuel gauge indicating the quantity of fuel in each tank".

I tend to agree that the fuel gauge needs to be operable, but there's no time to get the fuel gauge repaired before the check ride. Any advice?

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Yes, per §91.205 a fuel guage for each fuel tank is required for day / night VFR and IFR flight is required to be operational.
You could argue as others did that it only has to “correct” when on empty and I would agree but it has to read something. The other way of looking at it is that the fuel guage has to read something other than empty when their is fuel in the fuel tank.
If your airplane has an approved MEL, it might be allowed to be inoperative provided you verify the amount of fuel in the tank, but for your initial CFI test do not take a chance of busting because of an unairworthy aircraft.

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Remember the Tomato Flames acronym.  F is for fuel gauge.  You must have a functioning fuel gauge.  The acid test is safety.  Do you feel safe flying an airplane with an inop fuel gauge.  I would tend to want to get a ferry permit to get it to a repair facility, or better yet, get it fixed where it sits if you can.  There are too many fuel exhaustion accidents (preventable) per year to take a chance like this.  I know this sounds a little over-reaching, but as a CFI, you are the prime example to the flying public.  To show your willingness to take a chance on an inop fuel gauge sends a dangerous example to your potential students that the Pilot Examiner or FAA Safety Inspector should flunk you for.  Get it fixed then take your exam.

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“I tend to agree that the fuel gauge needs to be operable, but there’s no time to get the fuel gauge repaired before the check ride. Any advice? ”Seems like a no-brainer to me.  You have an unairworthy airplane you’ve been training in and you’re contemplating taking a checkride in it?  for a CFI? BTW, Part 23 says the fuel gauge must be *calibrated* to read 0 when there is no usable fuel in the tank.  Being calibrated to read 0 doesn’t mean that this is the only indication that needs to be accurate.  All scales must be calibrated at a certain weight, and the error increases the further away from that weight that you get.  Even so, the error is usually required to be within a certain range.  Part 23 doesn’t publish that range, but likely there is one.  Someone I know has requested an LOI on the topic from the FAA’s General Counsel’s Office, but it won’t be available until October.

Note: That letter was not published by the FAA General Counsel 
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In reading the above responses a couple of thoughts come to mind.  While by regulation the fuel indicators must function, relying on them for anything other then an indication of possible fuel present is more dangerous then not having a guage at all.  Our flight school had 36 aircraft and there wasn’t a guage in any of them that was even close to accurate.   Many times a student pilot or CFI would request fuel for a plane by reading the guages (without comfirming visually) only to find the tanks topped off.   And conversely, taking off with what they thought were full tanks only to land an hour later with one tank dry.The comment:” There are too many fuel exhaustion accidents (preventable) per year to take a chance like this.  I know this sounds a little over-reaching, but as a CFI, you are the prime example to the flying public.  To show your willingness to take a chance on an inop fuel gauge sends a dangerous example”

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While I wholly agree with the assertions that physically checking and monitoring the fuel quantity using known values is the best practice, the reg is very clear about what is required to be working at all times.  If you fly with a fuel indicator broken (which it clearly is), then you are essentially shooting yourself in the foot.  Yeah, you might get away with it, but then again, you might not.Also, in regard to MEL’s, 91.213 is very specific that any equipment required to be in operation by regulation (such as 91.205) by default can’t be included among the inoperative equipment in an MEL.

Flying with an Inoperative Fuel Gauge - Legal or Not?

A Forum Dialogue about Fuel Gauges in Aircraft

I'm not sure where to post this so I guess I'll just post it here.

So today while pre-flighting my club's 172. I flipped on the master switch to check the fuel gauges. The right fuel gauge, indicated correctly. While the left fuel gauge however, was pegged on empty, even though there was full fuel in the left tank.   I know that fuel gauges should only be accurate when they are empty,  however under 91.205 it states that an operative fuel gauge(s) indicating the quantity of fuel in each tank has to work for a VFR day flight.

I asked the mechanic and he frowned upon me and gave me a lecture on how "fuel gauges should only read zero when empty blah blah," and that I could still fly the airplane.

Wearily I went and asked of one of the CFI's in the FBO and he told me If there is fuel in the tank and the gauge indicates zero or empty then its just an inaccurate gauge. If however, there is no fuel in the tank and the gauge indicates fuel, then that is an inoperative guage.

My question is, I am legal to fly? And what are you thoughts on this? I really dont want to be nit-picky about regulations on the airplane that I fly but, that is my name going into that logbook and I just didn't want to risk it.
Thanks!

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"You wrote this, so it should answer your question.  A further question could be: What is so critical about flying the particular mission you're seeking to (a pleasure flight), that would require you to go against the above? Especially if something were to happen on that flight that attracted Fed attention, related or even unrelated to the inop gauge? Would the club back you then?"

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"Tell the club to fix their stuff. There's no excuse for that kind of Mx laziness, and allowing it or making excuses for it with the "kick the can down the road" mentality they seemingly have, only perpetuates the problem."

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I'd say no, till it is either fixed or deactivated in accordance with the MMEL.The whole "it only has to be accurate at zero" argument to me is moot, It is currently at zero AND it is not accurate.   A broken clock is right twice a day.

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Dip your tanks and use those numbers in your calculations. Flt time x Rate of fuel burn = Gallons of fuel needed then add in your fuel reserves. I don't rely on what a fuel gauge in a 172 says.

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Personally, I wouldn't fly it. I certainly don't want to nitpick a plane apart, but the thing is, the fuel gauge isn't doing anything *at all*!

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I'd fly a plane that had a gauge reading "some fuel" when there was, indeed, some fuel in the tanks, and reading "empty" when it's empty.

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But having a gauge sitting on "empty" 100% of the time isn't acceptable, in my opinion. What's the point in even having the gauge then? Might as well just draw a picture of a gauge on the panel with magic marker, because it would be just as useful.

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Ultimately, I'd pull the "would you rent this plane to a fed?" question on them. If they wouldn't be willing to show it to a FSDO inspector, they need to fix it.

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Notice where the "zero" comes from. It is a guideline for when the fuel gauge must read zero. This is to keep manufacturers from using zero "total" fuel when calibrating the gauge instead of "usable". Other than that there is no mention of gauge "accuracy" in the reg

Also.
Notice the word "operable" in the Part 91 reg?Is the gauge in an "operable" condition if it is always reading zero? No.

Is the gauge in an "operable" condition when reading inaccurately? No.

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I've talked to the maintenance officer for the club and he said he will check it out tomorrow. But I'll definately crank her over and taxi her next time if it ever happens again. Thanks! For all your guys input, it really helps a lot. I knew it wasn't legal,

But yet for some strange reason the mechanics and CFI's at the FBO had a million ways to explain and get around it.

Aircraft Fuel Mismanagement Cause and Effect

Aircraft Fuel Mismanagement - Cause and Effect

This is what we know about aircraft fuel instrumentation 

• "Maybe they’re also more in the habit of keeping an eye on the clock in flight, even sneaking the occasional glance at those notoriously inaccurate fuel gauges."  
• "Airplanes are legendary for having inaccurate fuel quantity gauges"
• "These devices are notoriously inaccurate, showing empty when there are gallons left in the tank and showing full for the first 1/2 hour."
• "Aircraft fuel gauges can be notoriously inaccurate."
• "Without a means of measuring fuel flow, you must rely on the aircraft fuel gauges or total time of flight. Aircraft fuel gauges are notoriously inaccurate (they are only required by the FAA to read accurately when displaying empty)." 
• "Aircraft fuel gauges have a well-deserved reputation for being unreliable and the FARs only require that fuel gauges read correctly when they are empty!"
• "Second, as others have said aircraft fuel gauges have historically been poorly designed and grossly inaccurate. Many will indicate something significantly different in a climb vs a descent and there are some airplanes with fuel gauges that are designed to read full until a substantial amount of fuel has been consumed."
• "Don’t bet your life on your fuel gauges, visually check the fuel level by “dipping” all tanks. Some aircraft models have notoriously unreliable fuel gauges."
• "All light aircraft gauges are notoriously, infamously and reliably, unreliable."
• "FAA safety guidance information states that fuel gauges are subject to malfunctions and errors, and certification regulations only require that a fuel gauge read “zero” during level flight when the quantity of fuel remaining in the tank is equal to the unusable fuel supply. Therefore, fuel gauges should not be depended upon for checking the fuel quantity in a tank"
• "Sounds great in theory, but I have not yet seen an accurate Cessna fuel gauge, Ever. A fairly expensive AD would be the only thing that would ever change that."
• "Unfortunately, fuel quantity gauges in aircraft are often inaccurate at quantities above zero. While this does not mean that they can be ignored, it does justify the use of another tool to provide a more accurate total picture of the fuel quantity."

... and on and on and on and on and on.

This is who takes the blame.

• "The pilot's inadequate preflight preparation, which resulted in fuel exhaustion, and subsequent loss of engine power during cruise flight."

• "The pilot's inadequate in-flight planning/decision which resulted in fuel exhaustion. A contributing factor in the accident was the pilot's inadequate preflight planning/preparation to ensure an adequate fuel supply was available for the intended flight."
• "The pilot's inadequate preflight planning which led to fuel exhaustion and subsequent loss of engine power."
• "A loss of engine power due to fuel exhaustion during approach, inadequate preflight planning/preparation by the certified flight instructor (CFI)."
• "The pilot's inadequate preflight inspection, which failed to determine the fuel supply in each fuel tank, and his mismanagement of the fuel supply, which resulted in fuel starvation."
• "A loss of engine power due to the pilot's inadequate preflight planning which resulted in fuel exhaustion."
• "The pilot's inadequate preflight planning and his failure to verify fuel consumption during flight that resulted in fuel exhaustion and subsequent collision with obstacles and the ground."
• "The pilot's departure with insufficient fuel for the planned flight, and his improper in-flight fuel management, which resulted in a total loss of power in both engines due to fuel starvation."
• "The pilot's inadequate preflight planning and failure to verify the amount of fuel onboard the airplane prior to departure, which resulted in loss of engine power due to fuel exhaustion."
• "The pilot's inadequate preflight preparation and failure to verify the fuel supply, which resulted in fuel exhaustion and subsequent loss of engine power."
• "The pilots improper preflight planning and preparation which resulted in a loss of engine power due to fuel exhaustion."
• "The pilot's failure to refuel, resulting in fuel exhaustion and a subsequent loss of engine power."
• "The pilot's inadequate preflight and mismanagement of the fuel supply, which resulted in fuel exhaustion."
• "The pilot's inadequate preflight planning of fuel required for the flight that resulted in fuel exhaustion and the subsequent loss of engine power."
• "A total loss of engine power due to fuel exhaustion as a result of the pilot's inadequate preflight fuel planning."
• "A total loss of engine power during a go-around due to fuel exhaustion as a result of the pilot's inadequate preflight planning."
• "The inadequate preflight inspection by both pilots, resulting in a loss of engine power due to fuel exhaustion."
• "A total loss of engine power due to fuel exhaustion as a result of the pilot's inadequate preflight planning."
• "Improper planning/decision by the pilot, which resulted in fuel exhaustion due to an inadequate supply of fuel."
• "A loss of engine power during approach due to fuel exhaustion as a result of the pilot's fuel mismanagement."
• "A total loss of engine power due to fuel exhaustion as a result of the pilot's inadequate preflight fuel planning."

... and on and on and on and on and on.

I am suggesting the aviation community take a closer look at the causes and effects of Fuel Exhaustion and Fuel Starvation events. 

Fuel Exhaustion - Are We Set Up To Fail

Our expectations are so low for aircraft fuel level gauging systems, They are hardly ever relied on.

In fact when we educate new pilots this is typically what is said.

• The first one is taken from the AIM

FUEL REMAINING—A phrase used by either pilots or controllers when relating to the fuel remaining on board until actual fuel exhaustion. When transmitting such information in response to either a controller question or pilot initiated cautionary advisory to air traffic control, pilots will state the APPROXIMATE NUMBER OF MINUTES the flight can continue with the fuel remaining.

All reserve fuel SHOULD BE INCLUDED in the time stated, as should an allowance for established fuel gauge system error.

• The second one from the Irish Aviation Authority

Aircraft fuel gauges can be notoriously inaccurate so it more reliable to “dip” the tanks to establish how much fuel is onboard. However, make sure that your dipstick is calibrated to suit your aircraft type, the aircraft is parked on level ground and the fuel level has been allowed to stabilise before you dip.

• The final one from AOPA  Flight Training Magazine

Use the clock - not the fuel quantity indicators on the panel - as your fuel gauge. In other words, plan and track your fuel consumption based on endurance, not range. Unlike range, endurance is not at the mercy of winds. Besides, those fuel gauge indicators probably won't be very accurate except when they read empty - a setting you should never see. 

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In fact the pilot mantra given to prevent Fuel Starvation and Exhaustion is  "PREFLIGHT, PREFLIGHT, PREFLIGHT  

So what do we normally look for in a PREFLIGHT inspection - tires, brakes, oil level, security of the flight controls, condition of the prop, security of the fuel caps.   Basically all the stuff you can't check in flight.

The implication here is - you have only one chance per flight to check your fuel level - & that one chance is at your PREFLIGHT inspection.  - If you avoid that critical step, you are flying on borrowed time buddy.

Here is the rub  - you are supposed to be able to monitor your fuel level throughout your time in the air.

Another Pilot Mantra could just as easily be be "INFLIGHT, INFLIGHT, INFLIGHT.  That INFLIGHT scenario would be the pilot comparing anticipated fuel level, to actual indicated fuel level.  This would be the pilot vigilance stuff, you know the cross checks of fuel remaining from the calculations to what is onboard.  

Fuel Gauges are required instruments and found on all powered aircraft - So yes the FAA actually expected them to work.  ---  I bet you are surprised.

You are, by design, supposed to be able to see how much fuel you have at any time while you are in the air.   It is the law, it really is, and it really is a good idea.

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In 1974 (yes that long ago) the NTSB initiated a study on Fuel Starvation,  in this study,  they found that there were some aircraft that rarely had a fuel starvation event,  and they also found some aircraft that were prone to the issue - Most aircraft as you might guess were average in this regard.

SO what this study pointed out, it didn't really come right out and say it,  but it was pretty clear that fuel exhaustion wasn't just a pilot thing  - 

If it were, pilots being human - some good, some bad & most of them average would equally suffer fuel starvation in any aircraft.  It would not matter which aircraft you flew.

An average pilot in an average aircraft might have a fuel starvation event - but not really that likely.

An average pilot might never experience a fuel starvation in "X" model aircraft, but that same pilot might be assured of a high probability of fuel starvation if he flew "Y" model aircraft 

As General Aviation is slow to change - some of those aircraft are still in production.  In fact some of those aircraft in the study are still flying.

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So what did the Aircraft Manufacturers recommend in the 1974 Report:

• Two manufacturers recommended a separate Low Fuel warning system. 

• One manufacturer recommended that a more accurate and reliable fuel level system be developed. 

• One manufacturer believed that a "one tank system" would be beneficial.

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So what did the NTSB recommend in the 1974 Report:

• Specification for a low fuel level warning that would operate independently of the existing fuel gauging system.

• Specification for a more accurate type fuel quantity gauging system. 

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That was 40 years ago - so 

Where Are We Now! 

I am guessing from the picture,  that we are still on the road to find a solution.

PA28 Hits the Road - Out of Fuel

Out of Fuel, Pilot Lands on Highway

Flying Magazine

By Stephen Pope / Published: Jul 16, 2013

Related Tags: Pilots, Adventures & More, News

Courtesy of WSOC

Enlarge Photo

A North Carolina pilot late last night successfully landed his single-engine Piper Cherokee between cars on Highway 321 a few miles short of Hickory Regional Airport after running out of fuel.

The pilot, Eric Klein, told a reporter for WSOC that when he ran out of fuel he was too low to make the airport and so he decided to set his airplane down on the northbound lanes of the highway, using the lights from the cars as a guide.

“I was coming back from Clarksburg, West Virginia, and should have had three hours of fuel left in the plane,” Klein told the news station. “I had excessive fuel burn for some reason and only had two hours and 10 minutes, and ran out of fuel about five miles short of the Hickory Airport.”

Klein managed to land his airplane without hitting anything, bringing it safely to a stop on the road in Granite Falls, North Carolina, at about 11 p.m.

No NTSB Action 

Aircraft Fuel Totalizers - A Self Fuel Filling Prophesy

One of the more difficult things to measure is liquid fuel on a moving vehicle.  

This is true of aircraft, boats and heavy equipment.  

By it's very nature, liquid fuel refuses to stay still.

So to address these issues with fuel level sending technology,  we have turned to fuel flow instruments and fuel totalizers.  

These instruments measure the fuel flow to the engine and remove that fuel volume from an owner/operator entered starting fuel value.  They can give you a  knots per gallon indication. 

This can be done by several methods - we can count injection pulses and duration or we can get a sensor to measure fuel on the way to the engine,  and in injected engines fuel on the way back to the tank.   There are several sensor types that will perform this function

Some of our cars do the same thing - only they reset when we fill the tank or in other words when the fuel level reaches full.

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Many owners will swear by the fuel totalizer and it's uncanny accuracy.

I filled the tank and then burned 35 gallons of fuel.   When I refilled - I put 35 gallons back into the tank.  

Sounds good - and a justification for the expense of having this equipment installed - However an aircraft tank filled in the same manner and in the same location - the fuel totalizer is a self - fuel filling device.

• I will never run out of fuel with this equipment installed.

• I don't need fuel gauges 

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So what does the FAA say about fuel totalizers 

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.  

Taken from  FAA AC 23-17C

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The only issue with the FAA message above is that it was written for aircraft engineers, certifying new aircraft or modifications -  

It really should be shared with the pilot and aviation maintenance community.   

Why not?

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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

Vulcanair - Partenavia P.68 Fuel Level

Vulcanair - Partenavia P68 Fuel Level Sensor 

We delivered the first digital fuel level units for Vulcanair P68 formerly the Partenavia.   This is the first factory installation of our digital fuel level system for a European manufacturer.

It is exciting to realize the potential of our fuel level patent on a worldwide basis.

While our business with Cirrus Aircraft involves pilot owners from around the world.  These pilots and operators are praising the new level of accuracy we have brought to their aircraft and fleets.

Working with manufacturers directly as we have done with Vulcanair brings a whole new family of professional owner operators to realize the benefits we can provide for fuel level indication for this family of aircraft.

While we are continuing a focus on supporting the aviation market,  we are working with several manufacturers in the automotive and marine industries to introduce our patented technology into these platforms.

We will be excited to announce several new customers and developments in the near future.