Eurocopter Deutschland Gmbh MBB BK 117 C-2 N145HN accident near Pittsburgh, Pennsylvania

Probable cause

Maintenance personnel’s failure to properly secure the left vertical fin cowling during recent maintenance, which resulted in its separation and subsequent contact with the tail rotor system during flight.

NTSB analysis

The accident flight, which was an on-demand air medical flight, was the second flight of the day following maintenance work that had been performed on the helicopter earlier that morning. The commercial pilot reported that the flight was uneventful but that, after landing, he noticed that the left vertical fin cowling had partially separated and contacted a tail rotor blade. Further examination of the helicopter revealed that the right vertical fin cowling remained secured but that 8 of the 11 fasteners on the left vertical fin cowling were unlocked, consistent with maintenance personnel not properly securing them following the maintenance work that was performed earlier that day.

Text from the NTSB. Open the NTSB docket for ERA16LA265 for the full record.