What was found
CREW REPORTS: FLIGHT ATTENDANT REPORTED ABNORMAL SOUND FROM ENG 1 DURING START, CREW SHUTDOWN ENG, RESTART WITH SAME RESULTS, NO REPORT OF ANY ABNORMAL ENG PARAMETERS OR EICAS MESSAGES, ENGINE WAS RUN AT 50% N1 WITH ALL PARAMETERS NORMAL. ACCOMPLISH CHECKS WITH NO DEFECTS FOUND. T-S AND FOUND APU SURGE VLV BAD. REPLACED VALVE AND DID SEVERAL ENGINE STARTS, ALL NORMAL.