I must say I'm confused here, and open to being corrected. But my understanding was that capacitative probes work by having a capacitor comprised of coaxial plates - a tubular outer plate and a solid inner plate with an air gap. The capacitance of the probe is proportional to the co-incident area of the plates and the dielectric constant of the air between them.
When you put this probe into a fluid it essentially becomes two capacitors in parallel - one with an air dielectric and the other with a fluid dielectric. So the capacitance changes such that it is the coincident area of the plates which are immersed in fluid times the fluid dielectric constant plus the coincident area of the plates above the fluid times the air dielectric constant.
As such the probes themselves only ever measure fuel *level* in the tanks, and any conversion to gallons/litres/lbs/kgs/pickle-bottles or WHY is achieved with calibration curves in the metering system. This would suggest that if the tanks were filled with warm fuel such that the gauges showed half-full, at the end of a cold night the gauges would indicate a lesser figure for the same amount of fuel UNLESS the fuel metering system included a temperature/density correction system of some sort.
Is my understanding wrong?
PDR