Fuel Sensor

[Bandit 153]

Is there any way a 1974 337G with long range tanks can have only two sensors in each wing instead of three?

[Pete Somers]

No, you need all the sensors to make up the complete system. Calibration of the system is based on 3 sensors and the capacitance signal conditioner is a 3 sensor system.

Cheers
Pete

[Roger]

I don't know the differences in the various models and tank configs, but my 80-H has 3 tanks in each wing (75 gal per side) all connected with upper and lower hoses, no main/aux setting like in my previous 70-E. Much easier system, no chance of overflowing the mains by burning down the aux, no vapor lock from the aux without a pump, etc..

Anyway, there is a sensor in the top of each outboard tank, and one in the top of each inboard tank next to the wing root. These 2 sensors send their analog data to a box overhead in the cockpit, and it calculates or combines (somehow) the appropriate average signal, and sends it to the fuel guage.

No 3 sensors for the 3 tanks.

[Bandit 153]

Thanks for your replys. There are indeed two sensors for the three tanks in each wing in the Pennycap fuel sensor system. What I now need to know is how to determine if I am having a sensor problem or a controller problem.
The gages both come up to at least a zero reading and then fluctuate slightly between zero and 5 gallons. There is approximately 25 gallons in each wing.
The continuity on all the wiring checks good.
I have a couple of AP's helping on this however we do not know how to check the sensors without opening up the wings and tanks and removing them.
Anyone have any experience with troubleshooting the contoller and/or the sensors in the Pennycap system?

[Pete Somers]

You need a capacitance test set that plugs into the plugs on the signal conditioners in the roof and you will be able to check the capacitance of the sensors against the service manual. Cessna did a test set complete with all the leads and connectors for all the Cessna range, Bendix also did one. It is the only way you can troubleshoot the capacitance fuel system and calibrate it.

Cheers
Pete