They will work with an older gauge - they are not FAA STC approved for an older gauge but it does work.
We demonstrated this to the FAA and they were not in favor of supporting analog gauging - as you read you will realize why they made this choice
This was a project the Cardinal Club started - Yes we now can interface to an old cessna gauge - if it is in good shape and has been modified to accept an external voltage regulator
The vintage Stinson gauge should be much better - but it will also have to be in good condition - we will need one to pattern the output as well as a tank profile
I wanted to share our progress on the CiES fuel sender calibration project.
I have been working with Scott Philiben and his lead engineer, Rick, on getting their 21st Century senders to work with our 50 year-old gauges.
Like many of you, I have not made the jump to a new panel and do not have space for a standalone fuel quantity display.
I really wanted a stopgap measure to help my fuel indication until I go glass.
I installed the senders over the weekend and will help write a tech page on that job.
The Reader’s Digest version is it took about 8 hours in total to do the installation.
About half of that was time spent running an additional wire to each wing, as I really wanted the power to the senders to be derived from the factory fuel sensing circuit.
I must say the new senders are an impressive piece of hardware/software and not to be taken for granted.
Scott and Rick came over for a calibration session and we spent about 5 hours collecting data points and perfecting the map for the fuel levels.
In the process, we ironed out several problems. The first hurdle is that the OEM gauges are not precise. IMO, I likely have some of the best functioning OEM gauges in our fleet, but they still leave much to be desired.
For example, it required 5.5 volts to drive the needle from empty to the ½ mark, but only took 5 volts to move the needle from “full” to ½. This ½ volt discrepancy was mostly in the middle of the gauge scale, but it took some compromise to keep the needle where we wanted it.
The other fatal flaw in the original Cessna design is that the gauge has no internal voltage regulation whatsoever.
This means the accuracy is totally dependent on buss voltage.
As we all know, buss voltage can vary quite bit from one plane to the next. A half-volt difference is as much as a ¼ tank of error. Not acceptable! So… we added a 10 volt regulator to the b+ side of the gauges to give them a rock solid reference. Then it was a matter of trial and error collecting data on the gauge. With some effort, I’d say the results are pleasing.
The second half of the project was to collect the data on the tank. We captured the frequency output of the new senders at empty, 1/8, ¼, 3/8, ½, 5/8, ¾, full and over-full.
(My tanks hold 28 gallons each due to the Monarch caps.) Due to the sender placement and the dihedral of the wing, the float doesn’t start to move until 2 gallons are in the tank. So… “empty” is actually 2 gallons instead of 1/2. On the other end of the spectrum, we calibrated “full” as 25 gallons. Anything over 25 the needle will move to the right of full. (For 60 gallon
Cardinals, the tank is just longer, so the calibrations should hold true.) For instance, “half” a tank is still the same height of fuel in the tank.
All in all, I think we have very good results and I am eager to try it all out real world. Now that the data is collected, mapped and saved, CiES should be able to deliver analogue senders for us that work great! And, since they retain the frequency drive output, the jump to a digital display down the road is just switching the wire.
I hope this investment helps Scott and his team as well as our club. I know several of you are eager to get your hands on this kit and now it’s here! I will report more results in the coming weeks.
1946 Stinson 108-1, Franklin 165, at one time NX8306K
Posted : 08/11/2018 3:01 pm