What was found
F/A REPORTED PAX AT OVERWING EMERGENCY ESCAPE HATCH SEATS 20BA, EXPERIENCED NOISE & VIBRATIONS COMING FROM THE FLOOR AREA. LASTED FOR 15 MINS & ABRUPTLY STOPPED. FLT CREW MISINTERPRETED REPORT LOCATION AS AROUND THE LT ENG AREA. PERFORMED EXTERIOR GVI OF LT ENG COWLS AS A PRECAUTION, NO DEFECTS FOUND. FLT CREW DID NOT SHUT DOWN LT PACK & NO STATUS OR FAULT MESSAGES WERE NOTED DURING FLIGHT. OPENED LT & RT PACK BAY DOORS, OPENED LT MLG DOOR. RAN APU & BOTH PACKS WHILE CYCLING ON & OFF TO TRY AND DUPLICATE REPORTED CONDITION. NO DEFECTS NOTED IN PACK BAYS OR MLG WELL AREAS. PERFORMED A GVI ON TOP OF RT WING TO BODY FAIRING & OVER WING ESCAPE EXIT. NO SCREWS MISSING, BULB SEALS INTACT. LT WING ESCAPE HATCH HAS NO DEFECTS ON OUTSIDE. WORKED IAW AMM 57-05-03-212-819, AMM 56-21-01-210-802-C1, AMM 52-05-03-212-809, AMM 53-05-03-212-875. PERFORMED OVERWING STEP HATCH HINGE PIN & DOOR INSP IAW AMM 05-51-38 AIRFRAME VIBRATION CONDITIONAL INSP. FOUND LT OVERWING ESCAPE HATCH HINGE PIN MIGRATED HALF OUT AFTER REMOVING LT OVERWING DOOR. IAW AMM 52-21-01, PUSHED HINGE PIN IN & STAKED IT SECURE. STILL REQURES ARMING OFF THE OFF WING ESCAPE SYSTEM IAW AMM 25-65-00. FIRST STEP F.