VIAVI supports many rotary and fixed-wing aircraft platforms with an extensive library of aircraft specific interface cables and units. Combined with a VIAVI Fuel Quantity Test Set, the test solution provides complete functional testing and troubleshooting of the fuel quantity system.  • PSD 737-2 FQIS - This interface measures the capacitance of the individual probes and compensator or total tank capacitance and also tests densitometers.  • PSD 767-2 FQIS - This interface is a Honeywell FQIS at FQPU interface unit.