Narrative:

I performed as an first officer on an ATR42. The crew had completed a 'quick-turn.' I had performed a preflight inspection, and found no abnormalities. Later, approximately 5 mins prior to departure, a certified mechanic entered the cockpit and made an entry in the maintenance log. I was busy (clearance, etc), the captain checked the maintenance sign-off, and mentioned nothing to me. After takeoff, approximately 500 ft AGL, we heard and felt a 'thud' on the left side. We discussed possible bird strike and possible compressor stall. Neither a visual inspection by the captain (on left engine) nor cockpit instrument readings revealed any abnormalities. The flight continued normally. Halfway to destination (hou), our company contacted us, and requested we inspect the aircraft for missing panels. A mechanic at dfw had seen something fall off an ATR at our departure time. Now the captain could see torn metal on top of the left engine. (The panel door opened for oil checks is the left one, which is outboard on the left engine, and not visible from the cockpit.) I inquired about the maintenance entry just before departure, and learned it was a routine oil check, signed off as complete by the mechanic. The flight was completed without further irregularities. A passenger noted the unlatched engine cowling as she boarded, but elected not to bring attention to it, as she saw the mechanic around the aircraft. Once in houston, when we all saw the whole door was missing, she mentioned seeing it unlatched in dfw.

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Original NASA ASRS Text

Title: ACFT EQUIP PROB. IMPROPERLY SECURED COWLING CAME OFF INFLT. THE ACCESS COWLING WAS OPENED FOR OIL SVC JUST PRIOR TO FLT. PAX SAW THE UNLATCHED COWLING, BUT THOUGHT THE MECH WAS STILL WORKING ON IT.

Narrative: I PERFORMED AS AN FO ON AN ATR42. THE CREW HAD COMPLETED A 'QUICK-TURN.' I HAD PERFORMED A PREFLT INSPECTION, AND FOUND NO ABNORMALITIES. LATER, APPROX 5 MINS PRIOR TO DEP, A CERTIFIED MECH ENTERED THE COCKPIT AND MADE AN ENTRY IN THE MAINT LOG. I WAS BUSY (CLRNC, ETC), THE CAPT CHKED THE MAINT SIGN-OFF, AND MENTIONED NOTHING TO ME. AFTER TKOF, APPROX 500 FT AGL, WE HEARD AND FELT A 'THUD' ON THE L SIDE. WE DISCUSSED POSSIBLE BIRD STRIKE AND POSSIBLE COMPRESSOR STALL. NEITHER A VISUAL INSPECTION BY THE CAPT (ON L ENG) NOR COCKPIT INST READINGS REVEALED ANY ABNORMALITIES. THE FLT CONTINUED NORMALLY. HALFWAY TO DEST (HOU), OUR COMPANY CONTACTED US, AND REQUESTED WE INSPECT THE ACFT FOR MISSING PANELS. A MECH AT DFW HAD SEEN SOMETHING FALL OFF AN ATR AT OUR DEP TIME. NOW THE CAPT COULD SEE TORN METAL ON TOP OF THE L ENG. (THE PANEL DOOR OPENED FOR OIL CHKS IS THE L ONE, WHICH IS OUTBOARD ON THE L ENG, AND NOT VISIBLE FROM THE COCKPIT.) I INQUIRED ABOUT THE MAINT ENTRY JUST BEFORE DEP, AND LEARNED IT WAS A ROUTINE OIL CHK, SIGNED OFF AS COMPLETE BY THE MECH. THE FLT WAS COMPLETED WITHOUT FURTHER IRREGULARITIES. A PAX NOTED THE UNLATCHED ENG COWLING AS SHE BOARDED, BUT ELECTED NOT TO BRING ATTN TO IT, AS SHE SAW THE MECH AROUND THE ACFT. ONCE IN HOUSTON, WHEN WE ALL SAW THE WHOLE DOOR WAS MISSING, SHE MENTIONED SEEING IT UNLATCHED IN DFW.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.