AOPA Pilot - May 2013

AOPA Pilot

The press is taking notice of the new digital fuel level senders in the new Cirrus aircraft.

In this case AOPA Pilot and Tom Horne

Here the new fuel level  senders are being discussed with the integration to the standard Cirrus Garmin Perspective Panel.

We agree that accurate fuel level makes it much easier to manage fuel and payload 

The dialogue we started a year and a half ago 

That accurate fuel level in aviation will allow for a higher level of integration, and relieve pilot workload

These innovations are reaching the light of day and in now in production

Tank level balancing and enriched warnings are now reality

Cirrus SR22 Fuel Level Retrofit

Feedback on the the CiES system....

While my aircraft (NA G3 #3813 Perspective) was at Leading Edge Aviation in Tampa for an annual, I had the CiES digital fuel system installed. The crew at LEA had recently received the benefit of Scott Philben's tutelage on the intricacies of this installation, and I was in line next for the retrofit. Two points of observation:

From This

1 - Fuel quantities are now precise and crisp. No longer do I tend to disbelieve fuel gauge indications because of erratic needles.

 Now there is no "negotiating" with myself of how much fuel I probably have. The installation includes calibration at 2 gallon intervals from "Zero Fuel" empty to full.  In my opinion, the replacement round gauge on the center panel is superior to the Perspective MFD indication.  Fuel quantity and balance is abundantly clear.

To This

2 - Choice of shop doing the work is very important. With the changes in wiring harnesses among all the iterations of Cirrus aircraft, there are a several unique and significant distinctions for each application. You need a knowledgable, detail-oriented, and thorough installer. I was fortunate to have one at Leading Edge Aviation.

Contact Steve Miller if you want this job done properly.




Finally, thank you Scott Philben for extending the OSH incentive, motivating me to get this system in my airplane. After seeing the results, I think the discount I received should more appropriately have been a premium paid to you. 

Flying Magazine - May 2013

Flying Magazine

Well we have been waiting for this -

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

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

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

Not the Fuel Totalizer - the Fuel Level System 

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

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

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

I

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

Not Fuel Totalizer -
The Fuel gauges

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

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

and attention to detail 

We are very proud that our efforts are being recognized 

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

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

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

Please look to 

aviationconsumer.com

for more information and other informative articles

A Tale of Two Aircraft or Adventures in Aviation Fuel Level

Opportunity

We had been supplying OEM Fuel Quantity Indication Systems to Cirrus Aircraft G3 and G5 aircraft for a year with great success and we had obtained a Supplemental Type Certificate to retrofit this system to legacy Cirrus G3 Aircraft.  As we had the STC for the Cirrus it was only a small change to include the G1 and G2 model aircraft into the mix.  Generally Cirrus Owners had indicated that the G1 / G2 aircraft had better fuel reporting than the G3 brethren,  however we knew that the technology used by these early fuel sensors would eventually fail and without an OEM business and obligation,  the prior vendor was free to raise pricing to support this limited production.   We smelled an opportunity.

So we jumped feet first in retrofitting early Cirrus Aircraft.   The first indication we had that something was amiss was from a retrofit owner, he reported that the system looked good, but no comment on the accuracy of fuel level information.  This report stood in stark contrast to our experience on the retrofitted G3 and new G5 aircraft where fuel level reporting was deemed to be a notable highlight.  We had another customer install - same result - Gee it looks great, but no comment on accuracy in reporting.   I had heard about issues with the original G1 / G2 fuel level, but I attributed them to the potentiometer technology used to report fuel level.

We still felt we had the best system out there and we sold one more G1/G2 kit.   This owner was not so blasé about the accuracy - he noted and documented where the system was showing inaccuracies over his fuel totalizer system.   We had his calibration data from the Cirrus Service Center and his report that he lost 5 gallons every time he switched tanks.   We were confused - our system seemed to be able to leap tall buildings and burn through steel - inaccuracy in reporting was not something we had seen in the several years it took to develop our fuel level sensor.

Discovery 

So we set up the test tank with his calibration data, and started to run tests - the system performed flawlessly for us - it reported the same volume going up or down as we had initially found with calibration.  So what gives -  We had notated that aircraft structure prevented the Inboard fuel sensor (there are two in each wing for this aircraft  Inbd and Outbd)  from reaching it's full travel - and we set this limit up with a plexiglass box and tried the recalibration again.  Same result - nearly flawless recording, however we did notice one thing - when we depressed the Inbd sensor slightly by 1/4 inch or so we saw a 5 gallon decrease in fuel volume.

The Smoking Gun

We delved a little further - the sensors are actually located in separate tanks - one inbd of the other - the inbd tank (Collector) being much smaller connect to the outbd tank (Main) with fuel lines.

So with fuel being drawn out of the inbd tank the level in that tank must go down 1/4 inch.   Well was this true in the aircraft - we had reports for our system and the prior vendors loosing 5 gallons when that wing tank was selected.  We knew that it was consistent - if you depress the outbd sensor - the change is progressively smaller and not uniform.  Depressing the inbd sensor  invariably gave a 5 gallon decrease each and every time,  as long as some amount of measurable fuel was present in the main tank.  We asked the question "Could this tank level be effected by fuel pump suction"   So we modeled the system confirmed it with a little computational fluid dynamics,  Sure enough  5 gallons

So why 5 gallons - remember these sensors are in separate tanks see right - but in combination they measure the total fuel volume.  When the inbd sensor goes down due to a level change locally in it's smaller tank volume - this amount is subtracted from the larger main tanks -  a quarter inch in a 3 gallon tank is peanuts - a 1/4 inch in a 40 gallon long tank is well - 5 gallons.   The logical reason the manufacturer used the collector tank for the inbd location of the sensor,  is that this location is the best place to measure zero fuel level or the level of fuel just above the unusable amount.

How Do We Fix It.  

As we started our work on replacing aircraft fuel sensors in the field - we noticed a lot of subtle bends in the float arms used to optimize the travel on the 60 degree arc potentiometer cards These potentiometer cards are used in legacy fuel quantity systems.  We started looking carefully at what this was doing for the sensor, and it was all about geometry or in other words   How do you get the most bang for your buck with 60 degrees of potentiometer travel and 60 discrete data points - one per degree.  As an example Beechcraft Bonanza goes from least accurate at a full tank to most accurate as the tank drains, this is actually true of a few Cessna Aircraft as well,  It's what tends to happen in a small town.   

So why is this true - well - Float sensors have a few limitations -
First and foremost the float has to float Second as the float swings through an arc it goes from most sensitive at about 45 degrees above horizontal -- to least sensitive
at horizontal --  back again to more sensitive again at 45 degrees below horizontal -

This is a typical Sine function for those who remember trignometry  - and this is especially true for float sensors, as increasing fuel is the measured as the sine of the angle the float makes with the measurement system.   So these subtle bends in legacy fuel senders were making use of this fact to optimize their reporting capability.

We what if we bent the arms in a similar manner - could we can get the same result,  a fuel level output biased to be more and less sensitive as required.   We had not crossed that idea, as our patented sensor system  had a 180 degree travel limitation and 1000's of arc data points.  The CiES fuel quantity system due to the ability to render small changes into a discrete output,  accuracy due to geometry was not needed.  Given that - could we utilize geometry for a similar but opposite benefit - could we make the inbd unit less sensitive at the top of the collector tank and mask the small change brought about by fuel being sucked into the engine.  Time to run a few numbers.  It worked on the spreadsheet  - worked being a relative term -  it is less sensitive to change at the top of the tank, so out of a 5 gallon change we were now at 3 gallons  - not quite good enough.  OK this logic seems to offer some potential - what if we made the main outbd tank sensor more sensitive, trying to capture a subtlety in level.    Well in this combination,  less sensitive collector and more sensitive main tank  got down to just under the magic 2 gallon change.

Testing

Initial CiES Installation 

Time to run a few tank tests -  Eureka - the results from the spreadsheet matched the test tank data.  Excellent - time to document the revised sensor and cut metal for TSO senders to replace the ones in the field.

The Graph at the right shows the before condition of the aircraft.  You can see that the aircraft is in climb as both sensors are below the totalizer.  On the G1/G2 aircraft the senders run for/aft  - this tends to accentuate the discrepancy as the senders are real excellent angle indicators.

Notice that the right tank is nearly identical - gauge and totalizer prior to the update.  However the left tank shows a combination of fuel level error caused by the fuel draw and induced by climb.   I suspect that the fuel flapper valve in the left collector tank is sticky or there is a constriction in the line.

Conclusion 

Well we are waiting for a cross country flight to get a real assesment - However preliminary flights and taxi tests demonstrated that the results did carry over to the aircraft.   But as in all things aviation - you really want to see how this performs in the field.

First Report - Owner has flown the aircraft down to 20 gallons a side -- the system is accurate  and it matches the fuel remaining on the owners dip stick.  The fuel level change is in the range of 1 gallon when the tank is selected. 

It looks like we have taken a problem and turned it into an opportunity to demonstrate our capability - that's really what we are all about.

Talk with us - let us know the problems you might be experiencing in fuel level reporting - whether you have an Aircraft, Boat, RV, Truck  -

We solve problems with fuel level  - 

Cirrus SR22 Avidyne G2 and 6 Pack Retrofit

We are installing the first Cirrus SR22 G2 (And G1) Retrofit sender at Professional Air In Bend, Oregon.

The new sender designs were patterned after the existing unit in the aircraft.

The new sensor utilizes our patented technology found in the latest generation Cirrus aircraft.  Additionally our sensor did not require the steady bracket seen in the upper left.

If you ever have to remove a sensor to replace a gasket for example.  The access panel will not have to be opened.

We expect to have the aircraft buttoned up early next week and ready for calibration.   

Working hard to rapidly grow our customer base.  

Overnight - The world of aviation fuel level measurement changed

Just like the classic instrument six pack.

Seemingly while you weren't looking  -   The days of simple capacitive and resistive fuel senders disappeared and were relegated to history. 

 You need only to look at the parts manuals for the latest Cirrus SR20, SR22 or Cessna 172, 182 & 206 single engine aircraft.     Take a real close look and  you will see terms like AMR and TDR  (Anisotropic Magneto Resistive & Time Domain Reflectometry).  And instead of a voltage or resistance output to be checked in the maintenance manual - you will see terms like CANBUS and Digital Frequency.  

So what changed ...... well quite a lot ...... the digital age hit fuel level.

• First ---- The FAA requires there to be working fuel gauges in aircraft.  

Fuel gauges that are accurate throughout the range.   Yes the FAA really wants accurate gauges in the aircraft not just at "Empty"

• The FAA in their regulations makes that clear -

• The pilot is required by Part 91.205 to have working fuel gauges
• The definition of working is:   Provide accurate fuel level through the  tank range.

• The aircraft manufacturer is required  by Parts 23.963, 23.1305, 23.1337, 23.1555 to provide working fuel gauges.

• These regulations very clearly indicate that the installed fuel gauges must give accurate fuel level through the whole tank range.
• Note:  Some of these requirements were recently revised.

• Second ----- The rate of fuel starvation events remained unchanged.
•  2 to 3 per week in the US 

For a long time,  excuses have been made for fuel level reporting systems in General Aviation aircraft.   

General aviation fuel gauges were (insert your own adjective) bad, pilots didn't trust them and pilots did not rely on the information they provided.   Plain and Simple 

Uncharacteristically,  the FAA turned a blind eye to the fuel level regulations they provided, tacitly acknowledging in their own documents and publications, that the state of the art was not up to the task.  

Pilots sought and effectively utilized "work arounds" - pilots relied on wristwatches only and aircraft manufacturers and avionic shops installed or incorporated fuel totalizer equipment in the aircraft.  

Iphone App showing fuel level 

Contrary to popular belief totalizers are not required equipment. but they will give pilots confidence in their fuel level.   They have proven to be accurate while in flight and provide a reliable cross check of the wristwatch fuel calculations  at any time.   You will find a fuel totalizer or range graph is on virtually every piece of modern avionic equipment.

Fuel leaking from an aircraft fuel pump

The posting on the web (pictured right) of illustrates succinctly the common complacency of having accurate gauges in the cockpit.   The particular pilot shows his "trusted" iPhone App illustrating a half tank - this app standing in stark contrast to the values depicted on the aircraft fuel gauge.

So why did the FAA really want working fuel gauges in the aircraft.  

Nothing but an actual working fuel gauge .... can tell you exactly what you actually have onboard the aircraft.   

Case in point --- Fuel leaks at a pump are one of the hazards a working gauge will detect.

You would believe that somewhere in the digital age and the era of MFD avionics, the simple fuel gauge would be relegated to the trash heap.   

However 

--- No Pilot Calculation -- 

--- No Totalizer ----

--- No Stop Watch ----

--- No Range Map ----

Only a working aircraft fuel gauge will let you know what you have in your tank and modern technology can give you that information .  

Welcome to the digital age in fuel level reporting 

   

Cirrus Retrofit Update

CIRRUS AIRCRAFT RETROFIT

Cirrus Fuel Level retrofits are now occurring throughout the world.

Wells Aircraft in Hutchinson Kansas was the latest 

Don, Scott and the rest of the team at Wells did an excellent job with the retrofit and took these pictures to show how well the system integrates to the Cirrus Aircraft 

Wells Aircraft Website


 This illustration shows the new CIES Fuel level
sensor on the Left and the replaced sensor on the Right.   Notice the increased area for fuel sealing on the new design, the smaller float and sealed Circular connector with gold plated pins.  The quality improvement is evident.

 Here is a close up of the Engine page on the MFD in the Cirrus Aircraft.  This gives you  the view of how the fuel level is depicted on the screen immediately adjacent to the Fuel Total




This illustration shows you confirmation of the fuel level remaining in the tanks as well as the fuel burned during the flight.  Given that you inputted the initial amount correctly they should match throughout the flight.



A closer view of the MFD depiction

This shows how well the new gauge integrates to the cockpit center console.  Notice that it gives you the same information as the Perspective MFD and also gives a numeric value for fuel.   If you exceed the manufacturers POH fuel imbalance the more full tank will turn yellow and flash to indicate the tank you should now select.  Simple

Another view of the Cockpit installation on the aircraft.  Notice even how well we matched the black anodizing on the instrument.   Attention to detail does not end at accurate representation of fuel level.

 Here we show the map view on the MFD with fuel level on the left side of the Perspective Screen

 A closer view of the fuel level displayed on the aircraft

Resistance is Futile

When you are talking about Fuel Level.  

When we designed our new digital fuel level sender we gave a lot  of thought on how to interface with older aircraft systems.

The question was:

Could we produce an resistance output to mimic an existing resistance fuel level reporting system.  

There would be a few clear benefits:

• We could interface with many more legacy aircraft 
• Incorporation of our system in aircraft already using resistance based sending would be easier.

However some of the issues of legacy aircraft were directly related to relaying resistance through the aircraft wiring as issues with resistance can provide false or error prone signals.   Resistance measurement on an aircraft was identified by us early on in the design process as not the most favorable method for accurate fuel measurement:

• Aircraft have long wiring runs
• There are multiple sensors and connections
• The connections needed to be ordered to produce a series for multiple sensors
• There were other connections in the aircraft - bad connections produced resistance 
• There were multitudes of different resistance values even for the same aircraft
• There were amplifiers in some aircraft to address the issues above
• The wire run was subject to aircraft vibration 
• The gauge quality and accuracy in legacy aircraft was - not ideal

The favorable aspect of resistive gauging was that it was easy for the average mechanic to diagnose.

• All they needed was an Ohmmeter.

• We had heard stories of Cessna 210 Centurion and Cessna Twin Aircraft with the dreaded Cessna breakout box to tune and diagnose the capacitive system.

So what we needed was a simple digital signal that could be read with the modern equivalent of a ohmmeter  - the Digital MultiMeter (DMM).  We can now get a digital frequency output of any connected sender.

We found that Digital Frequency gave us clarity for fuel level information over all the known wiring challenges - corroded contacts, poor splices and induced signals.  More importantly it gave us a good signal or nothing - induced errors did not conspire to give bad fuel level.

What seemed more natural is that the signal was similar to that used by the fuel flow transducer.  It seemed a natural  - and we could read the read and diagnose the signal on a DMM.

When we sat down after months of delivering a fuel level sending product that had zero issues and was easy to diagnose.  ---

We had come to  realized that we had found the best method for reporting fuel level on the aircraft and a communication standard for any application we applied our product to

General Aviation News - Press Release

Home → News → Aircraft → Accurate fuel gauges for aftermarket Cirrus

Accurate fuel gauges for aftermarket Cirrus

February 12, 2013 by Ben Sclair Leave a Comment

REDMOND, Ore. – Pilots are taught from an early age to not trust their fuel gauges. Cies Inc. wants to change that with its TSO’d fuel senders. The Digital Fuel Level System is now available as a retrofit on the Cirrus-line of aircraft (SR20, SR22, SR22TN and SR22T).

The system will measure fuel volume within 3% at all levels, within 1% when fuel volume is less than 50% and display the data on an Aerospace Logic or J.P. Instruments gauge.

“I love having the fuel flow quantity on the MFD like the new 2013 Cirrus Aircraft,” said David McGregor, Cirrus SR22 owner. “But the icing on the cake is the redundancy with the new Aerospace Logic fuel gauge that sits next to the fuel selector.”

Cies is working to expand the number of aircraft models, both certified and experiment, the Digital Fuel Level System will work with. The system costs $3,000 plus 16-18 hours of installation labor.

More information from Cies at 541-977-1043.

More news coming soon 

CIES Has New European Installation Centre

CiES Inc is proud to have RGV Aviation 
join our list of Installation Centers.  They are excited to be able to offer their Cirrus customers the new CiES  Fuel Level retrofit for SR22T, SR22TN, SR22 & SR20 Aircraft.

This modification brings legacy Cirrus Aircraft the benefit of the new factory Gen 5 digital fuel level sensor solution.  

RGV - A Cirrus Platinum Service Center -  Based at Gloucestershire Airport (EGBJ), is a family run Aircraft and Avionics maintenance business established in 1973.  As an established EASA Part 145, FAA Repair Station with EASA Subpart G and Irish Aviation Authority Subpart G approval, they have the ability and capability to support you and your aircraft, regardless of your requirements.

CiES  - A design and manufacturing business to incorporated to redefine the measurement of fuel.   CiES patented technology for measuring fuel is intrinsically safe - Non contact,  highly accurate and has proven itself reliable under the harshest conditions.   We brought accurate fuel level to aviation 

What can we do for you