Abstract: A fault protective device (48) for limiting the maximum current and voltage applicable to electronic components and wiring (26, 30) located in the fuel tank (10) of an aircraft. Particularly, a fuel gauging system circuit (18) extends from a generator (20) located outside the tank to at least one probe (14) located in the tank and from the probe to instrumentation (24) outside the tank. The device is electrically coupled to the circuit at the tank wall (28) and includes a voltage clamp (50) and series inductor-capacitor resonant circuit (46), so that the resonant circuit provides a low series impedance when applied with a signal at the operating frequency of the input signal applied by the generator but provides a high series impedance when experiencing a signal of a different frequency indicative of a system fault.