New Video - CiES Operation

Beech Customer Responses

Beech Customer Responses

I have the CiES frequency senders, with matching Aerospace Logic gauges.

Working with Aerospace Logic requires patience, but in the end, the result is really spectacular.

Yesterday, at 8500 AGL, I ran both R&L Auxiliary tanks down to 0.0 gals, at 47:35 on the clock, precisely as expected... A few seconds later... Fuel pressure begins to fall, immediately switched back to left main.  

Accuracy... It's a totally new experience. I have two fuel totalizers. One Shadin and one in my G4.  Maybe having accurate fuel gauges is overkill... But it's an overkill that I like. 

The only caveat is that my shop wasn't particularly efficient with the remove / reinstall / remove / final install / calibrate process.   I have ALOT of money tied up in this.   But I don't regret it, and I would do it again. 







For anyone who is considering CiES fuel senders these things are awesome. They are well worth the work to install. I ran all new shielded conductor up to the back of my JPI 930. Finally I have a reliable and consistent fuel measurement in my airplane. 

Wow, who would have thought accurate fuel level was possible.

If your airplane is down for an upgrade I would send your old fuel senders to CiES.   This will insure that the senders are appropriately set up the first time.   Beech in all their wisdom made numerous different senders inverting the bolt patterns on some etc. 

CiES senders can work by resistance, voltage or frequency. I would chose at a minimum voltage if you can, Frequency is even better.
Scott @ CiES knows his stuff.


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The cost to retrofit CiES senders to a pre-74 B55 is around $3200 (plus installation). That may seem "outrageous" but it's only about 50% more than what it costs to have the eight (2 per tank * 4 tanks) senders "overhauled" and my experience with overhauled senders is not very good. At best the overhauled senders will perform as good as when new for a few years which is to say they're accurate to within about +/- 5 gallons.

Properly calibrated the CiES senders appear to be within one gallon.  In a Bonanza with two 40 gallon tanks or a post 1973 Baron there are only four senders so that cost is cut in half.

 IIRC the last time I checked, new (1940s technology based) senders from Beech were around $1,600 each or over four times what CiES charges.

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+1 on the CiES/ Scott Philiben Phan club. There's no better customer service than that provided by Scott. anywhere.

I'm still VERY happy with my CiES senders. You know, when something "just works", you take it for granted.   I don't really give my CiES senders much thought. 

They're underappreciated little heros quietly doing their job. Perfectly. All the time.

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AIRCRAFT FUEL GAUGES THAT YOU CAN TRUST 

"With over 12,000 units now flying, CiES has taken over the OEM fuel level sending field.   Our combination of outstanding quality,  reliability, and accuracy has made CiES the standard and the runaway industry leader for fuel level indication on all aviation platforms, GA, Utility, Rotorcraft for both reciprocating and turbine engine applications " 

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. 

Beech Baron Digital Fuel Sender Retrofit Part 6

Beech Baron 58 Fuel Level Senders

CIES Baron 58 Fuel Quantity Senders

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We have some results back on the Baron 58 Senders.    There was a slight glitch as the middle left sender somehow got caught on the initial calibration.  But that was rectified easily   

The result was a fairly simple curve with no major discontinuities - Nice Job.

Even better we got a good result in the air.  

We got the middle float unstuck on the left side, it was helpful that with a frequency output graph that you could pinpoint the problem remotely like that.

After it was free, we mirrored the calibration numbers on the right side with the offset we had from the first reading and They  seem very accurate,  within a gallon of the totalizer on the JPI 960.

Tank calibration curve

We put lots of work on this aircraft... we did air conditioner, new engines, props, & avionics.    The owner has flown in it,  but we are still tweaking and breaking in the new engines for him.   

So a gallon or so off of the totalizer on a 150 gallon aircraft -  Not bad at all. 

Legacy Beechcraft Senders

All dimensions for these new senders  were captured from a legacy set of Beech Baron 58 Fuel Level senders.  As the CiES design constraints are different from the legacy senders - there are a few little tricks to getting the right geometry in the tank 

For this short flight fuel level is in green and fuel flow in blue.  You can see the effects of pitch change on fuel level on takeoff and landing. But you can also see the steady drop in fuel level over time.


This was our first multiple sender summing aircraft and we are very happy with the result. 

We were looking forward to this system in the aircraft as it represents a chance for us to utilize the capability of summing multiple senders to achieve a single digital fuel tank output.  

Every day we see that we can meet or exceed  the 0.75% most stringent TSO quality standard.  In the case of the Baron - that would be 0.66% accuracy for fuel quantity. 

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 

Reliability and Continuous Improvement - CiES

Non-Contact Fuel Level Measurement

Recently we ran across an article in the Cirrus Owners Magazine  - Cirrus Pilot 

The article talks about the Continuous Improvement Process that Cirrus Aircraft utilizes in its aircraft design and production to improve reliability.

This article it discusses the complete paradigm change CiES made to aircraft fuel level measurement and Cirrus Aircraft's customer satisfaction with our non-contact fuel measurement technology.

As the article states - CiES Brought a Whole New Approach to Aircraft Fuel Level.  

An approach that changed fuel level reliability, so significantly, that it is no longer necessary to question your aircraft fuel level indication.

Take Your Fuel Level Indication to Un-Charted Territory and  Embrace the Reliability of the CiES Non-Contact, Magnetic Field, Fuel Level Solution

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? 

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

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.

AeroviePilot iPad Application Demonstration

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

Customer Responses to the Retrofit Cirrus Aircraft Kit

WHAT ARE THE CUSTOMERS  SAYING

David McGregor

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. ... 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 gauge 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.
I would HIGHLY recommend this a must have upgrade to your Cirrus. Get in line now and place your orders.

Jeff Bessett

I just picked up MY aircraft, N874T SR20 - G3 Perspective with the new CiES fuel gauge STC - WOW. team at Advanced at Lancaster PA did the installation on my aircraft - and

Lancaster Avionics next door - did the avionics (Perspective) so it DOES show up on the Garmin Perspective system.

I only have 30 minutes flying with this, however, I believe this to be a game changer for anyone that has worried about the accuracy of the fuel gauges in their plane.

Tom Conroy

My partner, Gary Price and I just picked up our Cirrus from Leading Edge Aviation where they installed the new digital fuel gauges. I cannot tell you how nice it is to have a tool such as accurate fuel gauges. By using these gauges, we will be able to accurately assess whether there is a fuel leak in the system as well as accurately managing fuel supply. The gauges warn you ( by turning yellow) when there is a fuel imbalance in excess of that prescribed in the POH.

On the return trip, we wanted to see if we could land with equal fuel in each tank. About 20 minutes from our destination, we noticed a 6 to 7 gallon differential between tanks, so we switched tanks, and when we arrived at our hanger, there was less than a half

gallon differential. For some crazy reason, that made our evening...

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.