Narrative:

While climbing en route through FL180 we experienced a loud bang from the right rear of the aircraft, with ensuing vibration, and yaw to the right. With engine indications and system indicating normal, I determined the problem to be an open #2 engine cowl. The large amount of drag produced, coupled with engine and airframe anti-ice on the #1 engine, as I elected too shut down and secure the #2 engine, required almost full trim for rudder and aileron into the good engine. We notified cleveland center of our intentions to return to willow run airport and the reasons for doing so. Upon landing at the airport, tower confirmed our suspicions, and stated the #2 cowl was open and missing the bottom portion. As we shutdown the engine and secured the aircraft we inspected the #2 engine. The bottom outboard cowl door separated in flight and the top portion was wedged upward and back into the rear portion of the cowl. The missing portion of the cowl appears to have fallen into lake erie. At this time, I believe that the engine cowl may have appeared fully latched to the mechanics on their transit inspection. I have seen instances where the bottom latch appears closed but the interior hook on the latch does not engage. In my preflight of the aircraft I discovered nothing unsafe or out of the ordinary. There were mechanics at the aircraft for the before start, all clear to start, and to taxi portion of the beginning of the trip. I believe the decision to shutdown the right engine prevented further damage and normal use of checklists contributed to the uneventful landing. I believe the pressure to quick turn an aircraft by company personnel may have put the mechanics under increased stress. The trust the crew has in maintenance must be reliable or there is no reason to have a mechanic at an aircraft after the crew has conducted a preflight. We performed when the problem arose as we were trained to do, and prevented further damage.

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Original NASA ASRS Text

Title: CHARTER FLT HAS LOUD BANG, VIBRATION, AND YAW, BUT ENG NORMAL. DETERMINE IT IS COWL SEPARATION. SHUT DOWN ENG, RETURN LAND.

Narrative: WHILE CLBING ENRTE THROUGH FL180 WE EXPERIENCED A LOUD BANG FROM THE R REAR OF THE ACFT, WITH ENSUING VIBRATION, AND YAW TO THE R. WITH ENG INDICATIONS AND SYS INDICATING NORMAL, I DETERMINED THE PROB TO BE AN OPEN #2 ENG COWL. THE LARGE AMOUNT OF DRAG PRODUCED, COUPLED WITH ENG AND AIRFRAME ANTI-ICE ON THE #1 ENG, AS I ELECTED TOO SHUT DOWN AND SECURE THE #2 ENG, REQUIRED ALMOST FULL TRIM FOR RUDDER AND AILERON INTO THE GOOD ENG. WE NOTIFIED CLEVELAND CTR OF OUR INTENTIONS TO RETURN TO WILLOW RUN ARPT AND THE REASONS FOR DOING SO. UPON LANDING AT THE ARPT, TWR CONFIRMED OUR SUSPICIONS, AND STATED THE #2 COWL WAS OPEN AND MISSING THE BOTTOM PORTION. AS WE SHUTDOWN THE ENG AND SECURED THE ACFT WE INSPECTED THE #2 ENG. THE BOTTOM OUTBOARD COWL DOOR SEPARATED IN FLT AND THE TOP PORTION WAS WEDGED UPWARD AND BACK INTO THE REAR PORTION OF THE COWL. THE MISSING PORTION OF THE COWL APPEARS TO HAVE FALLEN INTO LAKE ERIE. AT THIS TIME, I BELIEVE THAT THE ENG COWL MAY HAVE APPEARED FULLY LATCHED TO THE MECHS ON THEIR TRANSIT INSPECTION. I HAVE SEEN INSTANCES WHERE THE BOTTOM LATCH APPEARS CLOSED BUT THE INTERIOR HOOK ON THE LATCH DOES NOT ENGAGE. IN MY PREFLT OF THE ACFT I DISCOVERED NOTHING UNSAFE OR OUT OF THE ORDINARY. THERE WERE MECHS AT THE ACFT FOR THE BEFORE START, ALL CLR TO START, AND TO TAXI PORTION OF THE BEGINNING OF THE TRIP. I BELIEVE THE DECISION TO SHUTDOWN THE R ENG PREVENTED FURTHER DAMAGE AND NORMAL USE OF CHKLISTS CONTRIBUTED TO THE UNEVENTFUL LNDG. I BELIEVE THE PRESSURE TO QUICK TURN AN ACFT BY COMPANY PERSONNEL MAY HAVE PUT THE MECHS UNDER INCREASED STRESS. THE TRUST THE CREW HAS IN MAINT MUST BE RELIABLE OR THERE IS NO REASON TO HAVE A MECH AT AN ACFT AFTER THE CREW HAS CONDUCTED A PREFLT. WE PERFORMED WHEN THE PROB AROSE AS WE WERE TRAINED TO DO, AND PREVENTED FURTHER DAMAGE.

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.