What was found
FOUL ODOR FOLLOWED BY HYD NR 2 ISOLATION LIGHT. RETURNED TO DEPARTURE. R & R PCB'S 413JE-421JE WITH SUPPLIED PARTS IAW AMM 24-00-00-910-801. PERFORMED ENGINE RUN UP AND FOUND NO FOUL ODOR AT THIS TIME. NO ISOL LIGHT AT THIS TIME. PARTS REPLACED: CIRCUIT BOARD, PN: FE422, SN: 18556, CIRCUIT BOARD, PN: FE422, SN: 6015.