Narrative:

During the second leg of a 1+40 offshore flight, I had been circling a platform (right turn) 10 mins awaiting a helicopter that was refueling to depart so that I could land. I received a call to go to another platform for a passenger pickup. I rolled into a left turn to head for the other platform when I felt a sudden vibration of about 2 seconds duration. Immediately, I turned back to the first platform to land. The refueling aircraft was departing. Landing was uneventful. Post flight inspection revealed that the left hand engine cowling had opened in flight striking the rotor blades. Both latches were missing off the cowling. The rotor blades were scratched but repairable. These older cowling latches have a reputation for failing. We've had one previous fall off an aircraft. Post-flight revealed a cracked latch on the left side transmission cowling. There is an improved version latch made. We've had these latches back-ordered for 7 months. Manufacturer needs to increase production to get these latches to the operators.

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Original NASA ASRS Text

Title: ENGINE COWL CAME LOOSE AND HIT HELICOPTER ROTOR BLADE.

Narrative: DURING THE SECOND LEG OF A 1+40 OFFSHORE FLT, I HAD BEEN CIRCLING A PLATFORM (RIGHT TURN) 10 MINS AWAITING A HELI THAT WAS REFUELING TO DEPART SO THAT I COULD LAND. I RECEIVED A CALL TO GO TO ANOTHER PLATFORM FOR A PAX PICKUP. I ROLLED INTO A LEFT TURN TO HEAD FOR THE OTHER PLATFORM WHEN I FELT A SUDDEN VIBRATION OF ABOUT 2 SECS DURATION. IMMEDIATELY, I TURNED BACK TO THE FIRST PLATFORM TO LAND. THE REFUELING ACFT WAS DEPARTING. LNDG WAS UNEVENTFUL. POST FLT INSPECTION REVEALED THAT THE LEFT HAND ENG COWLING HAD OPENED IN FLT STRIKING THE ROTOR BLADES. BOTH LATCHES WERE MISSING OFF THE COWLING. THE ROTOR BLADES WERE SCRATCHED BUT REPAIRABLE. THESE OLDER COWLING LATCHES HAVE A REPUTATION FOR FAILING. WE'VE HAD ONE PREVIOUS FALL OFF AN ACFT. POST-FLT REVEALED A CRACKED LATCH ON THE LEFT SIDE XMISSION COWLING. THERE IS AN IMPROVED VERSION LATCH MADE. WE'VE HAD THESE LATCHES BACK-ORDERED FOR 7 MONTHS. MANUFACTURER NEEDS TO INCREASE PRODUCTION TO GET THESE LATCHES TO THE OPERATORS.

Data retrieved from NASA's ASRS site as of August 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.