What was found
FA'S REPORTED BANG IN CLIMB ON L1 DOOR WITH LOSS OF LIGHTS IN CABIN. SECOND BANG WAS AT FL300 WITH NO LOSS OF LIGHTS. CLARIFICATION: ON TAKE OFF DURING GEAR RETRACTION LIGHTS IN CABIN FLASHED ONCE FOLLOWED WITH BANG ON L1 DOOR. A MINUTE LATER SECOND BANG. 3RD BANG HAPPENED IN CRUISE AT FL300. NO PRESSUIZATION PROBLEMS NOTED. REMOVED FROM SERVICE. PRESSURIZED A/C REF E175 AMM 21-21-00-720-802-A. NO ABNORMAL LEAKS OR NOISES NOTED. PERFORMED PAX CABIN LIGHTS OPS TEST IAW E175 AMM 33-21-00-710-801-A. OPS TEST GOOD. RETURNED TO SERVICE.