Accident Summary
On March 6, 2024, about 2140 eastern standard time, a Eurocopter Deutschland GmbH MBB-BK117 C-2 helicopter, registration N191LL, was substantially damaged during a hover taxi at Purdue University Airport (LAF), West Lafayette, Indiana. The pilot and two medical crew members were not injured. The flight was conducted as a Title 14 Code of Federal Regulations Part 135 helicopter air ambulance flight. The pilot reported that during hover taxi, he felt a force on the pedals, the helicopter yawed right, and full left pedal had no effect. The helicopter landed hard, and the crew egressed without further incident.
Maintenance Background
The accident helicopter was maintained under an approved aircraft inspection program (AAIP). From February 29 to March 6, 2024, maintenance was performed at the operator's hangar in Indianapolis, Indiana, including troubleshooting a pedal feedback discrepancy. Tasks included verification of the yaw SEMA angle, control cable installation, rigging, replacement of cables and actuators, and a friction check of the tail rotor blade mounting forks. During the friction check, the T-bolt and its two attachment bolts were removed to facilitate the work, but this was not documented in the work order. One mechanic reinstalled the T-bolt with bolts finger-tight to hold the tail rotor head position, but was then reassigned. The bolts were not torqued nor safety wired. The yaw trim actuator replacement ultimately resolved the pedal feedback, and the helicopter was released for service.
Postaccident Examination
On-scene examination by the FAA revealed substantial damage to the fuselage, tailboom, vertical fin, horizontal stabilizer, tail rotor assembly, and one main rotor blade. The tail rotor pitch change bellcrank was not connected to the pitch change slider. The T-bolt and its two attachment bolts were missing. One bolt was found on the ramp; the second bolt was found in the No.1 engine bay, and the T-bolt was lodged in a honeycomb panel near the fuel cell. The pitch change bellcrank spherical bearing moved smoothly. The attachment bolt holes did not show elongation or damage. One found bolt had flattened threads; neither had safety wiring. The cockpit pedal movement resulted in movement of the bellcrank at the vertical fin.