What was found
CREW VERBALIZED ELECTRICAL ODOR IN THE CABIN FOLLOWED MUSK. APU ON, NO PAX ON BOARD. T/S ODOR IAW WC 0550-2002. PER GVI OF APU COMPARTMENT W/ BLACKLIGHT INSIDE INTAKE PLENUM. NO OIL VISIBLE W BLACK LIGHT INSIDE INTAKE PLENUM. PER STE 5 OF WC 0550-2002, PERF LEVEL B DECONTAMINATION OF THE ECS AS WELL AS DECONTAMINATION VARIANT - 10 OF THE BLEED AIR DUCTS.ERF DUCT BURN OUT FOR APPROX 50 MINS. PERF IDLE RUN W/ BLEED AND PACKS. NO ODOR DETECTED. FLT CREW ON BOARD AND VERIFIED OK FOR SVC. (LP: 9197370, AIRCRAFT WAS GROUNDED)