Because Owning And Flying Your Beechcraft Can Be Done Safely AND For Less Money!
  Beechcraft Fuel Sensor Mysteries Revealed




The above picture is the typical Beechcraft fuel level sensor removed from the wing. Most Bonanza/Baron aircraft are configured with an OUTER level sensor that deals with about the first half of the tank and then an INNER sensor that deals with the second or bottom half of the tank level.






Here is what you will see when you open the sensor up. It is nothing more than a wire wound resistor, like a rheostat that is used to change the resistance in the circuit. The fuel gauges are essentially voltmeters measuring the drop in voltage caused by the change in resistance as the sensor moves up and down on the wire wound resistor element.



The problem creeps in when this wire wound resistor develops corrosion or a break in the wiring. Many owners have found good results in restoring accurate gauge readings by disassembling their sensors and giving them a good cleaning with fine sandpaper and/or contact cleaner solvent.


There is no seal on the sensor housing, it functions immersed in the tank. Since the resistor is

grounded, the resistance to ground is reduced by the slider.  There is always a constant path to ground so there is NO arcing.


There is play in the shaft to bushing interface. Air containing dust and normal pollutants enters the tank through the vents as fuel is displaced. These contaminants over the decades are believed to cause the corrosion and coating of the wire wound resistor that results in erratic or no readings at all from that particular sensor.


The fuel gauge system wiring varied greatly over the years depending on SN. So please research the wiring diagram from your shop manual for your particular serial number.


Do you have fuel gauge "modules" with adjusting pots on the back of them? Suspect problems there? Check with Beech Talker Hyland Lyle to rent or buy his "tester" for your gauges. His tester instructions and contact info are HERE


Hyland's tester is used on:


F33A E772 & up


V35B D10120 & up


A36TC EA1-EA272


F33C CJ149 & up


A36 E1111-E2110


B36TC EA273-EA319 EA321-EA388


See Birks Aviation for detailed info on the in cockpit fuel gauge "modules" and their replacement modules.



Pictures courtesy of Beechcraft owner, David T.


See a few great sources of fuel gauge repairs and overhauls HERE


web statistics