Bell 427 N427AL accident near Indiantown, Florida

Probable cause

The inflight collision with birds, resulting in damage to the rotor head assembly and a subsequent forced landing and rollover.

NTSB analysis

The pilot reported that, about 25 minutes into the flight, he maneuvered the helicopter to avoid large birds. The pilot felt something impact the upper right side of the helicopter near the main rotor mast area. The helicopter began shaking violently and became difficult to control. He immediately decided to abort the flight. During the landing attempt, helicopter control was lost; the helicopter entered a left spin, impacted the ground, and rolled over. The main and tail rotor systems and the fuselage sustained substantial damage. The immediate decision to abort the flight after impact with the birds most likely aided the pilot in executing an emergency landing.

Evidence of bird remains were present on components of the rotor head, two of the four pitch change rods, and the tail rotor. Both pitch change rods with bird remains were separated from one of their attach points. The bird remains were removed and sent to the Smithsonian Institute for identification. According to the report, male and female Black Vulture DNA was found on the pitch control rods, pitch control linkages, and the tail rotor.

Examination of the rotor head parts found two pitch change links failed in tensile overstress; one of these exhibited an inward bending that could have been caused by a bird strike. The damage to the other pitch change link was most likely caused by the dynamic rollover as the rotor blades impacted the ground or other helicopter components. The accident sequence most likely initiated when the birds struck the pitch change rods.

Text from the NTSB. Open the NTSB docket for ERA12LA379 for the full record.