Cessna Pennycap Press Release - Flying Magazine May 1968

Cessna Pennycap

Copyright Flying Magazine May 1968

Curiosity got the best of us the other day, and somebody wondered if there was a similar example to a disruptive fuel level technology in General Aviation aircraft.   I indicated that there was a different system and it enjoyed a brief and limited success.  This system came out in the late 1960's and was featured on Cessna aircraft.

I went for a magazine search for press releases, curious to see what virtues would be given to a better fuel quantity system.

This system was produced by Consolidated Airborne Systems - which still operates out of a garage location in New York state.

The headline for the article was entitled 

GAS GAUGES THAT TELL THE TRUTH 

"General aviation airplanes - those engineering marvels, this distillations of technical wisdom and aeronautical magic incarnate - use fuel measuring devices of the same arrangement that plumbed fuel quantity in automobiles since the Model A  float tipped rods that electrically drive instrument panel needles to positions approximating the volume of fuel left.  Many such devices are off by as much as 25 percent" Copyright Flying Magazine May 1968

Many mechanics swore at these systems, many are swearing at them still.  The never lived up to the billing as corrosion on these low cost systems quickly robbed them of any accuracy advantage.  If you remember - Penny was to indicate "low cost" and cap was to indicate "Capacitive"  i.e. Pennycap system by its marketing title was a low cost capacitive fuel system.

"For not much more than the cost of an annual, then you'll be able to have a fuel gauging system of honest go/no-go quality.  Can you hold in the soup for 45 minutes at your alternate, or should you declare an emergency and tell them to get you down?  Can you afford to try and get out of that mountain strip with half full tanks and your present baggage load, or are your tanks more like three-quarters full?  It can make a difference." Copyright Flying Magazine May 1968

What is old is now new again - as 48 years later for the price of an annual you can have a CiES fuel gauging system of honest go/no-go quality. 

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

The Three Fundamental Truths About Aircraft Fuel Level

We have a unique perspective to aircraft fuel level,  in that CiES works daily on these systems.  We see the good, the bad and the downright ugly.

What we have observed and are sharing here is what CiES has determined to be the

Three Fundamental Truths about Aircraft Fuel Level Systems. 

Here they are:

If the technology of fuel level measurement can find the surface of the fuel reliably. 

• Floats that actually float or are allowed to float.
• A set capacitance based on fuel level in a tube (ignoring temperature & other fuel dielectric effects).
• Ultrasonics tend to get messed up with foaming fuel. 

If the basic sensor system can output a lot of data related to fuel level. 

• A capacitance fuel level system can output a theoretically infinite number of data points - but realistically in an actual fuel level device -  potentially 10,000 to 30,000 data points 
• Our Magnetic Field Technology has 10,000 to 12,000 data points.
• A legacy potentiometer system that provides maybe 50 or 60 data points (wiper and trace size controlling the data point size) 

If your fuel level display system can capture the complexities of a fuel tank curve  

• a non linearly marked fuel gauge or an Multi Function Display with a calibration feature

Then if these three criteria are met - you will have an excellent aircraft fuel level system - meet a few of them and your fuel level system will be functional. 

As we know the world isn’t perfect -  

To make a old aircraft fuel level system work well -  You need to make a unique potentiometer, carefully assemble it to reduce internal friction, maintain wiper contact and hope it all holds together and doesn’t corrode.  

Now combine the above with a non linear and an easy to calibrate gauge.  This is fussy work at best.

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Here is  our real world challenge  - 

• Say for example you have a simple fuel gauge marked with the same distance from Empty to 1/2 tank, & from 1/2 tank to full 
• We are all very familiar how long it takes to go from Full to 1/2 Tank and that it takes a fraction of the time to go from 1/2 Tank to Empty.
• The above is a fundamental universal truth. 
• Therefore because CiES can  - we load a tank table with a characteristic curve onto internal memory on the sender.
• Log, Sine, 3rd order, 4th order, 5th order, Non Linear - You name it - We can do it - challenge us.
• Of course we need the tank function and a simple gauge to get it right.
• Unlike a potentiometer - we don’t have to cram all that onto a circuit card by physically making the small steps with variably positioned traces, or onto a carefully delineated gauge.
• We have 10,000 reliable data points with our sensor technology - we just do it in software - easy peasy. 

Just don’t tell me that fuel gauges only have to be accurate at empty - we get all apoleptic.

Cessna - New Technology Non-Contact Fuel Level Sender

CiES Inc, Cessna Fuel Level Sender 

We are in the process of serial manufacture of a Cessna Fuel Level Sensor.  

Cessna Fuel Level Sender 

This fuel level sensor utilizes our patented magnetic field technology and carries FAA TSO Approval.  

Note:  TSO Approval is FAA component approval and not FAA installation approval.

We set out in 2010 to change the dialogue about fuel level indication in aircraft & we accomplished this by building an aerospace specific fuel sender design.  

Fuel Level Sender Exploded View

This new fuel sender design, while resembling older technology potentiometer fuel level senders, centers around a robust patented non contact sensor technology.  

The only common part between our fuel level sender and old technology is the float.  You can see the CiES attention to detail we are internationally known for.

Our goal was to design a fuel level system that had the potential of replacing many legacy aircraft fuel senders in the field.  Our initial fuel sender production was utilized almost exclusively by OEM aircraft manufacturers and to meet OEM requirements they utilized a robust proprietary digital output.  Unfortunately this output was only suitable for Garmin G1000, JPI 930 & Aerospace Logic displays and instrumentation.   We have produced over 7,500 non contact fuel level senders in this configuration and the results have been exceptional.

Our recently issued TSO allows us to reach and support a broader range of cockpit fuel indication interfaces and as a correlation allow CiES to spread it's wings so to speak.   This new sender design allows the CiES fuel level sender to output a variable voltage or resistive load giving us a nearly universal capability to support legacy aircraft.

As such, we are actively working on CiES fuel level solutions for many popular aircraft. 

Contact us and see if we have a solution for your aircraft.

Learn more on the CIES Inc Website

Cessna - Friggin Lasers in Their Fuel Tank

Hidden Costs Behind the High Cost of Aviation 

I had started to re-energize our 2015 marketing effort  and wrote a few blog posts about delivering magnetic field fuel senders to,  new to us,  European Aircraft and Helicopter customers.  We seem to be popular over there,  we may owe many thanks to Flieger editor Thomas Borchert  

To check on our progress on our google search listing placement,  I ran across a G1000 Cessna Fuel Sender for Sale on Ebay  and thought I'd share it.

This is a Meggitt TDR (Time Domain Reflectometry) Fuel Level Sensor for a Cessna Single Engine.

• Used Ebay Price is $1,800 each
• New Price from large Cessna Parts Jobber is $3,100
• Cessna List Price is $3,864.  

The Meggitt Fuel Level Sensors do look well made and come with a nice calibration sheet for your Cessna 172, 182 or 206.

Replacement Cost for 2 of these sensors on a Cessna would be $7K to $8K a Kit -  Installed cost would be well over $10,000 - This for a retrofit fuel level system on a Cessna 172 for heavens sake.  It is painfully obvious why there isn't a retrofit STC available.

Maybe some in aviation are correct,  airplanes are getting to be very expensive  - part prices contributing greatly.  But with a bit of creativity, it doesn't have to be.   

The caveat is,  that our Fuel Level Sensors met all the FAA TSO requirements that the TDR fuel sensor has met - and we do it for far less money.  I was told early on,  Engineering is not building the best without regard to cost, it is providing best performance at a price that is attractive to your consumer and the FAA.   

While I have heard that our FAA TSO fuel level sensors are expensive compared to legacy commercial grade resistance fuel senders, i.e. the kind of sensor they used to put in aircraft of the past.   I agree to a point on the expensive part arguement, but I truly feel CiES hit the target.  We provide improved aviation technology and performance at a competitive price. 

This Meggitt TDR sensor is not a well known change to the venerable Cessna Single Engine Lineup,  you would be hard pressed to know this was in your wing unless you queried the Cessna Illustrated Parts Catalogue.   There is no mention of this system any Cessna Marketing literature.   You'd think that a $8,000 fuel level system would be worthy of editorial or marketing content  - I guess it isn't.

Almost overnight the world of aviation fuel level changed and somehow nobody bothered to notice.

The TDR system works by shining laser light down a glass rod and measuring returns, so next time you come in contact with a G1000 Cessna owner - Let them know they have "friggin" lasers in their fuel tanks. I am going to bet they'll be surprised.

Magnetic Field Fuel Level Senders - Resistance Output

 Another Day And Another New Fuel Level Sender Configuration @ CiES 

While we discussed the Universal Output Sender in a previous blog post, it's much better to talk about an actual fuel level sender we are sending off to it's intended OEM manufacturer.   

This new configuration will output an equivalent resistance to be read by a gauge or the aircraft MFD.   While it appears on the surface to be easy it is actually the result of a 3 year effort to provide an output suitable for the aviation environment.   

Our senders are natively frequency output based, and this output has proven to work very well in our OEM and retrofit applications for Cirrus Aircraft,  but what we needed to do was convert that frequency to either a voltage or resistance output.

So we manipulate this native output to provide a variable voltage or a variable resistance.  

This unit for a new customer contains everything we wanted to provide;

• Frequency Output Fuel Level
• Slave Sender Input
• Resistance Output Fuel Level
• Fuel Temperature 

It is the culmination of making a Fuel Sensor that is compatible with most platforms out on aircraft & helicopter platforms in the field.

Cessna Cardinal 177 Fuel Sender Design Process

Can we offer a Retrofit CiES Fuel Sender for your aircraft. 

What are the steps we need to take: 

New Cessna 177 Cardinal Fuel Level Sensors 

• Obtain a a set of old fuel level sensors from the aircraft we are considering.  If the part numbers for the senders match the aircraft they are on, we are good to go.

• Ideally this aircraft should have a strong user base with an owner base that demonstrates their willingness to embrace new technology with their pocketbook.

• Discuss the compatibility with commonly installed MFD components or instruments.  CiES  Fuel Level Senders now has the capability of driving even old analog gauges in the aircraft (Universal Fuel Level)..

• Our market is the pilot / customer that is more concerned with fuel level issues and wants the required fuel level instrument in the panel to have the  capability of multiple point calibration.

Old Cessna 177 Stewart Warner and Leigh Fuel Sensors 

• Evaluate the existing sensor design -  For example the bends in these sensor arms are either to assist in installation and removal of the fuel sensor or to clear aircraft structure in the fuel tank.

• As our sensor design allows for an easily detachable arm - these bends might not be necessary and simplify the design greatly.

• We then proceed to manufacture a prototype sensor with our best guess for geometry.

Cessna 177 Cardinal Fuel Tank - Internal Shot

• Check the sensor in the aircraft fuel tank.  As you can see in the illustration - in this case the simple arm design works better in the tank and sweeps a better fuel volume being closes to the Spar and maximum chord point.

• At this point we qualify the design with drawings and procedures for the completed unit so that we can send these files to the FAA to have this configuration added to our TSO.

Fuel Tank with Prototype Sensor Installed 

• Once we have approved drawings we can can produce the required sender with a TSO Tag attached.

• The fuel tank is then drained, the aircraft leveled and braced only then is the zero fuel amount added.  There should be movement of the sender to be able to record an accurate zero fuel level, this is an absolute requirement.

• Fuel is then added to the tank incrementally and accurately to obtain data points for calibration.  We direct the installer to take special caution to insure tabs fuel value is accurately recorded by the fuel display.

• Equally the installer needs to insure full fuel level per the POH is also accurately displayed.   

Note:  All aircraft fuel tanks are built with expansion volume - Full fuel per the POH may or may not be to the neck on the filler plate.  This is very important as the aircraft will probably be fueled in the future on a ramp -

Varying fuel tank angles caused by imbalanced fuel filling - filling one side before the other

or 

The angle of the ramp typically created to drain water from the ramp surface.

Both of the above have an effect on apparent aircraft fuel level from simple visual observation.  

• A confirmation of entered fuel level and actual fuel level when the aircraft is in stable cruise flight may allow the pilot to correct for an erroneous starting fuel level value. 

• The final result is a happy customer with a new fuel sender design that has hundreds of data points to describe the fuel tank contents on their new MFD display or instrument.

Note:  While this seems to be an involved procedure - accurate fuel display on an aircraft requires this level of detail otherwise you might not get the information you need.

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 

A Universal Aircraft Fuel Sender

A UNIVERSAL FUEL SENDER

When we started manufacturing fuel level senders,  we had a specific customer in mind.   

In order to maximize our customers benefit for this technology, we made this sender nearly exclusive for that customers application. 

We received quite few inquiries for this fuel sender and most of them related to will it interface to our existing system.  

Sadly because we had tailored the sender to a particular aircraft and avionics interface,  we had to turn good business away.  

So step forward 3 years nearly to the day,  we had an opportunity to reinvent the fuel sender product and add new features:

First:   We have utilized a unique circuitry design to create a universal output:
                         - We can supply:  Resistance
                                                      Voltage
                                                      Frequency 

Second:  We can supply a  Fuel Temperature Output.  This feature is helpful for Jet A applications  where Pounds Fuel is the unit of measure.

Third:  We have supplied a pigtail to allow installation in tight spaces and flexibility in the Fuel Sender connection. 

We are trying to remove any barrier for you to have a more reliable technology for fuel level in your aircraft.

Contact Us for more information.

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.

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

CiES Inc Update

If we reflect on the past year we have accomplished quite a bit

• Secured a OEM contract on the most produced General Aviation Aircraft  - Cirrus SR20 & SR22.

• Obtained a TSO for producing this fuel level sender applicable to all aircraft.

• Received retrofit approval to install our TSO sender on all legacy Cirrus Aircraft. 

• Designed an LPG (propane) level sensor with iPhone/iPad interface

• Initiated OEM installation on the Gippsland GA-10 Turboprop, Discovery 201 & Vulcanair P68 Aircraft series.
  
  

• Achieved aircraft industry recognition for our accomplishments

What is now happening behind the scenes is truly impressive 

• Engaged in engineering design with several manufacturers for installation of our fuel level sensors on their aircraft platforms.

• Working three new aircraft platforms 

• Involved in several STC retrofit applications 

• Finalizing the boat level sensor to display at a major customer

• Engineering new aircraft systems and interfaces using our technology

• Planning for exposure in non aviation markets 

So we have been quite busy and very active - and look forward to next opportunity to demonstrate our capabilities

Aviation Fuel Level

Traditional Aircraft Fuel Sender 

Why don't my fuel gauges work?

Let us cover a few basics  

• Aviation industry has utilized level senders from other applications
• Aviation is not the largest market or the most financially rewarding for a dedicated fuel level sensing solution.

• Aircraft fuel tanks are larger than those for most other applications. 
• An aircraft carries more fuel.

• An aircraft has three degrees of motion freedom 
• The liquid fuel is free to move about.

There are other factors.

• Why not design a new system 
• Fuel Level Intellectual Property is hotly contested territory (a patent minefield) 
• A new aviation design must avoid other patents 
• The market share is small
• The perceived liability - Top 5 aircraft incident issue

• Fuel Level in Aircraft needs to be "Intrisically Safe".
• Explosion Proof 
• Limited Spark or Heat Energy in the fuel tank. 
• Non - Contact "The best solution" for Intrinsic safety is the hottest IP in Fuel Level
• Required for multi fuel and hybrid vehicles
• Required for vehicles with long term fuel storage - i.e. Boats
• Required in LNG / LPG

------------------------------------------------------------------------------------------------------------Fuel sending works in my car.

• Automotive fuel tanks are smaller
• What would be adequate for a resolving 16 gallons of fuel has difficulty with 3 times the volume.   
• If you have a boat - this is also an issue as you are well aware
• The variable resistor technology used in automotive applications doesn't scale well
• The variable resistor cards used,  allow 60 degrees of travel  - a good resistive card for aircraft or boats would require minimum. 180 degrees or more.

• Relatively stable fluid motion 
• The automotive sensor is exposed to some fluid motion but overall less. 
• Aircraft fuel can remain quite stable - however turbulence will creates concentrated fluid motion.
• This motion wears the resistive trace - so inadequate resolution of the variable resistor is now faced with increased wear.  From bad to worse.

• The basic requirements 
• Standard aircraft fuel gauges are calibrated only for the full and empty position.
• Caveat - new automotive systems are calibrated to the tank - great improvement
• Caveat - new aircraft MFD's allow tank calibration - Aerospace Logic, JPI, Garmin

• Almost daily use  
• The automotive sensor is continually washed with new solvent at every filling and fuel fills are more frequent. 
• Aircraft fuel can remain in the tank for long periods - it is designed to do so - however impurity buildup on the variable resistor are common at a fraction of usage time of the automotive application.
•  it is quite common to have your aircraft senders ultrasonically cleaned

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Propane Level Gauge

New requirements for intrinsic safety for all aviation fuel level systems 

• The general aircraft industry found that they could utilize a commercial off the shelf, patented float sending unit from the propane industry
• This met the new safety requirements and directly replace a float level legacy system.

• A Non- Contact solution - the resistance card was removed from the tank environment.
• Shock inputs from turbulent air can however de-couple the matched magnetic drive and the the gauge will take a set but in-accurate reading or drift back to the correct reading.
• Suffice to say - Propane Tanks were not meant to fly

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Aircraft Capacitive Sender Ad - 1948

Alternatives  - 

Capacitive Senders -

Conceived in the Late 1940's this aircraft fuel sending system set about to address the two most common issues presented above - fluid motion and resolution of the larger fuel quantity.   

These are the most widely used in aircraft above 12,500 lb 

Capacitive Sensor Benefits 

• Immunity from fluid motion 
• Greater resolution of the large fuel volume 
• Shapable to the fluid volume - tailored to the tank volume.

Capacitive Sensor Issues

• Difficult to Prove Intrinsic Safety
• The definition of the sensor is to utilize two metallic or conductive elements in the tank 
• The intrinsic safety requirement must be met with increasing the complexity of the system.
• It is a spark in the capacitive sensor that initiated the explosion in TWA 800 fuel tank. 

• Moisture Rejection
• An aircraft fuel tank breathes on ascending and descending - moisture in the air is constantly brought in contact with the fuel.  Sealing the tank is not an option.
• As the capacitive utilizes the fuel contents as an integral element of the level reading - this variable is very difficult to manage.

• What's in the tank - matters a great deal 
• Fuel must be:
• uniform 
• moisture-free
• stable and uniform temperature
• contaminant free
•  to give a consistent and accurate fuel level indication 

When you review the system above - the capacitive sender solved several issues with fuel level indication, however it brought a few of it's own limitations along for the ride.

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Ideal Aircraft Solution Characteristics

• Non Contact - New FAA Requirement
• Intrinsically Safe - 
• The alternative is proven safe electronics in the fuel
• Immune to fuel contamination

• Unaffected by Fluid motion 
• No wear items related to fuel level reporting

• High Resolution 
• Address the larger quantity of fuel in aviation systems.

• Simplicity 
• The best aviation solutions eschew complexity where a simple system provides equivalent benefit.

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CIES Inc AMR Fuel Level 

Float Based Level Sensing - Retrofits or directly replaces most units in the field

• Non Contact 
• No - Safety Issues 
• No - Fluid Contamination
• No - No moisture or fuel quality issues

• Immune to Fluid motion
• No wear of fuel level reporting system

• Resolution 
• Digital output
• More fuel level information 
• Integrity of the level signal
• Interfaces to modern avionic solutions
• Ability to output fuel temperature - Lbs fuel. 

• Simplicity




• No complexity required
• On the platforms we have been applied - exceed it's requirements

CIES Inc AMR  A sensor that was designed for and patented with the aviation industry in mind, but suitable for all high value applications.

Customer Feedback - Cirrus Retrofit

Folks I just picked up the plane this evening from Advanced Aviation in Lancaster PA.

Joel Glover and his team did an outstanding job installing the new CIES digital fuel sensors despite a steep learning curve on this first ever install.

The next one (an SR 20 was already in the shop) should go a lot faster as the first is always the hardest.

I had a chance to run the system through its paces on the short hop from KNLS to KMMU this evening.  I must say my first impression is WOW !  A huge improvement.

I love having the fuel flow quantity on the MFD now, but the icing on the cake is the redundancy with the new digital fuel guage that replaces the former analog version.

Really cool looking, but more important is the functionality.  I really like how you can flip between fuel quantity and the fuel burn graph, really helpful for fuel balance. 

The CIES team even made sure it dims with the instrument dimmer.

I will get some more time this weekend (during the daylight) to run it through its paces, but 

I would HIGHLY recommend this a must have upgrade to your Cirrus.

Get in line now and place your orders, I am convinced you will not regret it.

If you want to eliminate all your fuel level issues, this is the only way to go.

Like you I highly recommend Advanced Aviation in Lancaster PA as the place to get it done.  Joel and his team are the defacto experts now for this upgrade.