What was found
ACFT WAS UNDERGOING AN ANNUAL INSPECTION. DURING THE COMPRESSOR WASH/RINSE CYCLE THE CABIN WAS INSTANTLY FLOODED WITH SMOKE AFTER ACTUATING THE STARTING SYSTEM. AFTER FURTHER INVESTIGATION THE POWER WIRE (P46A00) WAS FOUND UNSECURE AT RT PWR JB, PN 974.03.38.143, SN 478, T4 CONNECTION. THE POWER WIRE ATTACHMENT HARDWARE NUT AT T4 WAS FOUND INSTALLED TO ONLY 3 THREADS WHICH ALLOWED THE POWER WIRE, P46A00, TO SHIFT ALONG THE T4 STUD ASSEMBLY CAUSING SEVERE ARCHING AND OVERHEATING. THE LOOSE CONNECTION CAUSED THE T4 GROMMET AND POWER WIRE PROTECTIVE BOOT TO MOMENTARILY IGNITE. THE LOGS SHOWED NO PREVIOUS MAINTENANCE IN THIS AREA.