A B737-700 WAS DISPATCHED IN NON-COMPLIANCE WITH THE ENG FAN COWL SECURED WITH ONLY ONE OF THREE LATCHES. COWLING DEPARTED ACFT ON LNDG.

Narrative

ON THE NIGHT OF WED JUNE 2004; I WAS ASSIGNED AN OVERNIGHT CHECK; HMU GASKET INSPECTION; CHIP DETECTORS ON #2 ENG AND A GPS MEL IN WHICH I PROCEEDED TO COMPLETE ALL OF MY ENG CHECK; CHIP DETECTOR INSPECTION AND HMU GASKET INSPECTIONS. I BEGAN AND COMPLETED #2 ENG HMU GASKET AND PROCEEDED TO COMPLETE #1 ENG HMU INSPECTION. UPON COMPLETION OF INSPECTION; I WAS INFORMED BY A RAMP PERSONNEL THAT MY ACFT IN PARTICULAR NEEDED TO BE REPOSITIONED IMMEDIATELY DUE TO AN ACFT SWAP. AFTER THE ACFT SWAP; I FORGOT ABOUT THE ENG LATCHES BECAUSE I HAD AN MEL ON GPS AND A STORM WAS BREWING AND I WAS UNDER THE IMPRESSION I HAD AN ANTENNA TO CHANGE. THE LIGHTNING HORN WAS GOING OFF; SO I BEGAN WORKING ON MY GPS MEL. WITH LIGHTNING PRESENT AND THE DISTRACTION OF THE SUDDEN ACFT REPOSITION; I JUST PLAIN FORGOT ABOUT THE LATCHES. HAD IT NOT BEEN FOR THESE DISTRACTIONS; I WOULD HAVE COMPLETED MY JOB ON THE ENGINES WITHOUT HESITATION. SUPPLEMENTAL INFO FROM ACN 621604: ON TOUCHDOWN AND THRUST REVERSER DEPLOYMENT; BOTH ENG COWLINGS ON #1 ENG SEPARATED FROM THE ACFT. THE COWLINGS WENT UP AND OVER THE WING WITH SUBSEQUENT DAMAGE TO THE L FUSELAGE; UPPER WING AND HORIZONTAL STABILIZER. ACFT HAD A NEW AIRWORTHINESS RELEASE WHEN WE STARTED IN ZZZ1 WHICH PROBABLY ENTAILED SOME INSPECTION OR SERVICING OF THAT ENG AND CAN ONLY SURMISE THAT THE COWLING LATCHES WERE NOT SECURELY FASTENED. THESE LATCHES ARE DIRECTLY UNDER THE ENG AND WOULD NOT BE EASILY NOTICED UNLESS YOU GOT ON YOUR KNEES TO INSPECT. CALLBACK CONVERSATION WITH RPTR ACN 621779 REVEALED THE FOLLOWING INFO: THE RPTR STATED WHILE WORKING ON THE AIRPLANE A THUNDERSTORM WAS APPROACHING ACCOMPANIED WITH LIGHTNING AND THE LIGHTNING WARNING HORN WAS SOUNDING. THE RPTR SAID AT THIS TIME THE RPTR WAS ADVISED OF A PLANE CHANGE AND IMMEDIATE MOVE WAS MADE TO THE GATE; OVERLOOKING THE ENG FAN COWL LATCHES. THE RPTR STATED WITH THE LATCHES NOT SECURED HE IS NOT CERTAIN IF ANYTHING HANGS BELOW THE COWLING INDICATING AN UNLATCHED CONDITION. CALLBACK CONVERSATION WITH RPTR ACN 621604 REVEALED THE FOLLOWING INFO: THE RPTR STATED IT WAS NOTED IN FLT OF A HIGHER FUEL BURN FROM THE ENG AND A SLIGHT VIBRATION THAT DID NOT INDICATE ON THE ENG VIBRATION INDICATOR. THE RPTR SAID WHEN THE AIRPLANE LANDED AND WENT INTO REVERSE; THE FAN COWL DEPARTED THE ACFT; INCURRING SERIOUS DAMAGE TO THE FUSELAGE AND HORIZONTAL STABILIZER. THE RPTR STATED THERE WAS NO ABNORMAL SOUND NOTED AND WERE ONLY ADVISED ON TAXI IN BY THE TWR THAT SOMETHING WAS LEFT ON THE RWY. CALLBACK CONVERSATION WITH RPTR ACN 621795 REVEALED THE FOLLOWING INFO: THE RPTR STATED THE WALK AROUND PREFLT INSPECTION WAS CONDUCTED BY THE BOOK AND NOTHING APPEARED WRONG WITH THE L ENG COWLING. THE RPTR SAID THE LATCHES ARE HIDDEN ON THE BOTTOM OF THE COWLING AND NOTHING LOOKED ABNORMAL. THE RPTR STATED THE CREW NOTED INFLT THE HIGHER FUEL BURN FROM THE ENG AND A NOTICEABLE LIGHT VIBRATION. THE RPTR WAS UNSURE WHAT POS THE LATCHES ASSUME WHEN NOT LATCHED.