Update to CiES fuel gauges - worth it?

Guest Discussion
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folks,
I am on the brink of becoming a cirrus owner (sr20 g2). here in the 11th hour of confirming purchase contract, I have a lingering question regarding the fuel gauges. as a very new pilot, it seems trust in the gauges is an item/uncertainty that I might not want to bother with (be distracted by) when flying any appreciable cross country. before I get started learning this new plane, would it be best to get the CiES update and remove those distractions of clear indications from each tank and reconfirmation of remaining range etc ?

very much appreciated
talix59

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They are nice, no doubt. I considered them, but my analog gauges work well and I often calibrate the totalizer numbers on the MFD when I top off fuel and they are always spot on so I personally didn’t see value in them.

I know others have less reliable readings from their standard setup and have gone with the upgrade.

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I agree - my analog gauges are quite accurate as well. In fact, my Cirrus analog gauges are much better than my previous aircraft including two models of Cessna and one Piper. I still don’t completely trust them and always cross-check with a physical “fuel stik” and the totalizer. Normally, all three methods are within 1-2 gallons of each other.

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Tom,
My plane is a SR20-G3 with Perspective - I had LOTS of drama with my factory fuel gauges - so when CIES became available, I was an early adopter. I feel that and the Berringer brakes are the two BEST upgrades I have done - next - SureFly mag replacement is on my list now that it is approved for my plane.
-J-

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Fuel gauges are never going to be accurate by principle. I think the CiES statement that the floats were never the problem but the sensors is pretty bold marketing. There is still mechanics involed, things get stuck, etc. The only reliable fuel indicator is looking into the tank. I would keep that in mind. No matter how accurate a sensor is, you will still need to visually check. Maybe it’s even better not to fall for a false sense of safety. And never think that this is a replacement for fuel planning and management in flight. Just my 5 cent…

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Bring new to ownership I would set that upgrade aside for a while……you’ll be spending lots of $$$ on all kinds of things til you get your plane de-squawked .

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From my experience, it won’t take away the distraction. I’d leave the gauges you have and get used to the plane. An engine monitor with fuel totalizer is the best for long range flying. You can see pretty accurately how much time in the air you have left.

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It depends on mission, personal cash flow, and how you look at risk mitigation.
There are three well established ways to in theory how much fuel you have when you are in the air.

  1. Gauges
  2. Fuel totalizer (assumes accurate starting point)
  3. Time (assumes accurate starting point and constant flight conditions)

For the second and third, you attempt to get sticks to measure the quantity in the wings, but the really only truly accurate known point is when the tanks are full. Therefore if you plan to fly with partial tanks to recover useful load to carry passengers you need to include some wiggle room or buffer to address the possible in-accurate starting point.

The other issue that the second and third do not address is a fuel leak before the fuel flow sensor. There are multiple documented cases of this issue in other aircraft, it tends to be older planes. And when you consider now that many Cirrus are roughly twenty years old, this becomes a greater concern.

Personally, I address both concerns by reducing the effective utility of the plane. I carry extra fuel, I know that the existing gauges on our G1 are kinda wonky (for lack of a better word) but good enough that I can see if I will need to land early.

I normally fly about 13.5 GPH in cruise, with 81 gallons that gives me 6 hour range. I normally plan for four hours at most, and start looking to land by 4.5 and will be on the ground by 5 hours. If the gauges match expectation, however a couple times they showed lower than expected, so I landed after 4 hours; when the destination was only 30 minutes farther.

Can I squeeze every last drop of fuel from the tanks and be comfortable? Not with the older sensors we have. However, personally I would use this only two or three flights a year. Therefore, I currently prefer to make an two or three stops a year (which my wife likes the extra bio breaks) versus spending the X thousands.

Tim

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all,

excellent feedback and very much appreciated. seem like the COPA is just as advertised - what a community. hoping to seal the deal and get my own experience started and be a permanent member.

thank you very much

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If your fuel gauges are accurate, stick with them. If they are off or need replacement the CIES are a great upgrade. They still are subject to getting stuck etc and shouldn’t be relied on as :100: accurate. Always visually check and compare with totalizer. For me it’s useful for peace of mind when I need to depart less than tabs. I consider it a highly recommended upgrade.

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Well - I am amazed at the legacy of marketing Edward Simmonds put forward in the late 40s regarding float senders. Edward was for lack of a better term, a wartime optimizer. Edward was sent to the US at the outbreak of WW2 to find innovations in the USA that could help the war effort in Europe. One of those innovations was the Elastic Stop Nut or Nylock This new company partially owned by Mr. Simmonds, contained his initials should not be missed and ESNA went on to capture the market and partially eliminate the tedious and time-consuming wire tying of fasteners in wartime. Edward’s next venture was to use an American capacitive process measurement system and apply this to aircraft. He hired a good Polish engineer to work on the program and came up with a new way to measure fuel in aircraft - using picofarads.

Edward was a marketing genius - his Simmonds Electroprecision ads depicting that floats won’t work in aircraft live on 70+ years after their introduction. I can’t think of another advertising campaign that has that long of legs. It is, however - Marketing and not factual. His ads depict a situation where neither his system nor the one he is replacing will work (Aircraft in a steep dive) he just fails to tell you that small factual bit of information.

So floats aside from 70-year-old legacy marketing - Cirrus has been using CiES senders since 2012. 1.) Cirrus does not stock CiES replacement senders for the existing aircraft fleet. 2.) The CiES Mean Time to Failure in the SR22T is over 90,000 hours or 9 Cirrus aircraft lifetimes. 3.) CiES has supplied over 90,000 fuel senders to the GA legacy fleet. So we can support bold marketing statements with factual information in fact we would be foolish to publish frosting in this litigious environment without the cake to support it.

Capacitive systems deteriorate over time and are subject to corrosion and contamination issues and are extremely sensitive to wiring issues. No capacitive system available for any aircraft has a guarantee of mean time to failure over 10,000 hrs. Capacitive systems require wiring in the fuel tank as the aircraft fuel is an integral electrical component in the system (See FAA Fuel Safety and Lightning Requirements) The no moving parts is an attribute, one that was hyped by Mr. Simmonds, but in my experience, it may be the systems only attribute. Measuring small electrical differences in an aircraft is challenging and is the reason for the dual redundancy of these systems in Transport aircraft. Imagine having a redundant fuel quantity system in GA.

Steel automotive senders in aluminum aircraft are/were the issue, as dissimilar metals in the presence of the water in fuel is the obvious failure point, not the fact that the float pivots. Aircraft float systems from the 1950s made from either Brass or aluminum still work and we have a storeroom full to illustrate this. Cessna 195, DC4, DHC-2

So yes - Floats are not the issue in fuel measurement as buoyancy works. Genius level marketing that floats do not work lives on in the collective aviation conscience. Poor design choices by a majority of GA manufacturers in the 1960’s, 1970’s and 1980’s reinforced that opinion.

The major safety takeaway is that no Cirrus outfitted with CiES senders has had a fuel starvation or exhaustion incident or accident related to fuel indication … to date (Knock on wood). This is now a 10-year-old statement and somewhere north of 20,000 Cirrus fuel senders.

So to some - workarounds (Time, totalizers, and visual inspection) are the key element to fuel safety as that is what most of us were taught. However, these workarounds used by themselves cannot make the same safety statement, as pilots suffer fuel related incidents and accidents at a similar historic rate without change over the last 10 years (Nall report as the reference)

So in this industry - independent data-supported marketing is crucial and definitely not bold.

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I love my CIES gauges but they won’t replace conservative fuel planning. If you don’t have a problem with the gauges work on conservative fuel planning first. Just my 2 cents

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I find it funny how how much emotion gets thrown in to these fuel gauge threads from both sides of the argument.

Probably the best advice so far.

For me, my original gauges were crap. Left gauge checked out at 35 gal and then would drop directly to 10 as levels in the tank dropped. I put in Cies gauges and they work great. They match the totalizer within a couple gallons which is nice redundancy.

Yes, Alexis, I know I can use a fuel stick, I have one.:grinning:

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I did not like the factory gauges on my G3 SR22T. You couldn’t read the gauges accurately…they were so small. It was hard for me to tell the difference between 10 gallons in a wing (fine) and 6-7 gallons, which is not fine.

I put in the Cies gauges, and was immediately happier with the more accurate and easier to read gauges.

My only complaint is that, while they were accurate above about 35 gallons (each tank) and accurate below 20, there was a dead zone in the middle where they indicated lower than the actual FOB.

Someone here on COPA (Jim B.?) told me that G3s need some additional hardware to get accurate mid-range fuel sending. I elected not to spend that money.

My priority was accurately knowing the FOB when it was less than 20 gallons, and CIES delivered that.

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David: Actually longer arms in the outbd sender solves that issue. I will have to check with Jim B as he might change all 4 arms, but that is the magic of Jim B and his analytical hands-on approach.

When we initially did this with Cirrus, we (plural) specified a tight tolerance for handoff, using the wing 3D model to establish float arm lengths. As a corollary, there was a need to show minimal change to the FAA, one intrinsically safe sender… Magnetically coupled resistance… for another… direct magnetic direction reading. It turned out that the G3 Wing Model and production G3 Wings are not exact representations in that there are assembly variances. So in some aircraft, a handoff is present where one sender stops on the bottom of the travel stop and the other is still pinned to the top. In some aircraft there is nothing.

We saw this in the retrofits for G3 and in a few production aircraft. Cirrus tightened tolerances on the wing build for the G5 model as well as installing the senders prior to the final wing skin bond. This also eliminated the potential for sealant on the float when installed in the aircraft wing.

Cirrus still specifies the arm length for the production senders which are identical for the retrofit. CiES has 600 models of aircraft on their STC , so we have other arms in stock and the assemblies are made to allow arms and floats to be easily replaced. We have a CNC Rod bender so arms are relatively easy to fabricate.

In the G2 retrofit, we expanded the travel arc and lengthened the arms slightly to allow measurement overlap.

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I would wait until you have owned the plane for a while, more than likely you will be spending money in other areas until you get the plane the way you want it.

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Reliable fuel pump gauges were real high on my priority list BEFORE I bought as well. However, after a very short amount of time flying with them, you learn to use the gauge itself as a backup indicator, never fully trusting it. The fuel totalizer is most important, but tells you nothing about fuel imbalance. You should go entirely on time. 7 months into ownership and my gauges are shaking out to be much more accurate than I anticipated. You’re going to find lots of little, nitpicky things you can spend your money on. Don’t replace for replacement’s sake!

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……Lasers……

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S,

We generally change the outboard arms. The sender sweep pre fill with fuel while monitoring outputs shows when a problem will occur.

Tabs area is the most inaccurate area on all Cirrus.

R

J

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My stock gauge were trash. Left tank read about 15-20 gallons LOW.

Better that 15-20 gallons HIGH but still not useful, and also quite distressing. Had to rely on the fuel totalizer, but in the very rare event of a leak that would not be helpful.

CiES is a very reassuring upgrade. In my case it is basically a necessity.