What was found
STRONG FUEL ODOR DETECTED IN CABIN. LOWER FUEL NOZZLE AT 6 O'CLOCK POSITION MISSING BOLT. THREADED INSERT IS STRIPPED CANNOT SECURE BOLT. RAN APU AND FOUND FUEL LEAK AT FUEL HEATER AFT CHECK VALVE UNION AREA. DIFFICULT TO SEE IF LEAK IS DUE TO SEALS OR UNIONS. APU NEEDS TO BE DROPPED TO REPLACE CHECK VALVE AND APPROPRIATE SEALS. MAY NEED TO CHANGE HEATER AS PRECAUTIONARY. REMOVED APU AND ROUTED TO SHOP FOR REPAIR AND TEST CELL RUN. REPLACED APU AND FUEL HEATER CHECK VALVE AND SEALS. OPS AND LEAKS CHECKS GOOD.