What was found
APPLIED A/C POWER AND CHECKED APU CB'S. CONFIRMED FAULT REPORTED BY CREW. CB "FIRE DETECTION APU 2601" TRIPPED AND UNABLE TO RESET IT. CYAN CAS " APU FIRE DETECTOR FAIL" WAS ALSO POSTED. UPON INVESTIGATION FOUND WIRE W197D20-4 (28VDC - SINGLE WIRE) DAMAGED. HARNESS W62455 WAS TOUCHING AND ARCING ON THE APU CASING DUE TO INCORRECT ORIENTATION OF THE CONNECTOR. INSULATION OF W18A20-4 WAS ALSO FOUND SLIGHTLY DAMAGED, BUT NO CONDUCTOR VISIBLE. DAMAGE TO BOTH WIRES WAS OBSERVED WITHIN 1 INCH OF CONNECTOR 054S1P1. NO OTHER WIRE DAMAGED FOUND. CARRIED OUT CONTINUITY CHECK BETWEEN CONNECTOR 054S1P1 PIN D & DC MPT #12 CONNECTOR 033A12P1B PIN 2 (DAMAGED WIRE) I/A/W GVIII-G700 WDM 26-13 REV 2, FOUND SATISFACTORY.