The Why of CiES

For pilots and aircraft owners of general aviation aircraft, it’s been a historical challenge to measure fuel level in the air.  Every time a pilot scans their fuel gauges, they want to assess the state of fuel remaining in the aircraft.   To give a pilot  better decision making tools in flight, functional fuel gauges are a minimum requirement.  For this reason the FAA mandated operational fuel gauges for all flight operations.  This capability is critically true if you want to utilize the maximum safe range of your aircraft.

The main problem pilots face is misleading information provided by traditional fuel quantity instrumentation. Even if a pilot knows the fuel gauges to be erratic, they still can lead to bad decision making.  Today, their best option is measuring fuel before flight.  This measurement is  typically made with a wooden stick or glass pipette.  Pilots use this starting known fuel level  and keep track of consumption in flight, but of course, they still run out of fuel.  One key factor missing in this method is knowing exactly among the multiple tanks on the aircraft, just where is the fuel located.    Let's be frank using a stick in a modern aircraft illustrates that we have given up on ever making the fuel gauge work. 

With a bulk of the general aviation aircraft aging beyond 40 yrs, the problem is only get worse over time.

If only there was a better way to measure fuel quantity in the air, then pilots could make better decisions regarding extending flights, balancing tanks or making an extra fuel stop.  This capability would lead to less fuel starvation or exhaustion events and better piece of mind.  With 400,000 general aviation aircraft flying, there is a clear opportunity to meaningfully impact safety on the breadth of worlds general aviation pilots.

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 " 

The "Zero Fuel" Myth - You know, Fuel Gauges only Need to be Accurate when Empty

You don't really need to know what happened after this true Accident Narrative - It is evident from the beginning.

Picture Draw Jerel Draw,  jereldye.com

Prior to the incident, I received an instructional ride and completed my C-172 checkout. I then flew with a passenger and solo, three flights, for a total of 5.3 hours in the bird.

In all three of those flights.

• I observed erroneous fuel quantity indications,
• Intermittent cycling of the fuel gauges to zero.
• LH Fuel Low Level Warning light coming on intermittently. 

An [instructor] told me this condition was well  known, typical for this aircraft and not uncommon for general aviation aircraft.

I discussed the erroneous fuel quantity indications with the Chief Pilot, and asked
him if I should write them up. 

He said no, that the indications were within the spec, which requires only that they
read accurately when empty.

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The statement that fuel gauges only read accurately when empty is repeated so many times in the aviation dialog.

 You would almost have to believe it is true.

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Actually far from it.

• It is a comment you hear repeated by many pilots, the magazines & AOPA / FAA Safety Briefs.  

• It is not uncommon to have bad fuel gauges in aviation, it is frighteningly almost the rule.  

What is true: 

• Fuel gauges are "Required" aircraft instruments for powered aircraft.

• They are required to be functional by design and in operation on the aircraft   -  Specifically:

• Read fuel level from FULL to EMPTY.  
• EMPTY needs to be calibrated at "Zero Usable Fuel"
• The Zero Usable Fuel is the fuel level,  where in the worst condition - fuel cannot be drawn from the tank.

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Designing, Maintaining or Flying an aircraft with bad or in-operative fuel gauges is illegal.  

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Why is it surprising that so many GA pilots run out of fuel.

I think the answer is obvious.

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