Accidents
NTSB Cites Faulty T-bolt Install in Tail Rotor Failure
No injuries reported after the air ambulance accident
A diagram of the installation of the T-bolt and associated attachment hardware onto the pitch change slider
A diagram of the installation of the T-bolt and associated attachment hardware onto the pitch change slider © Courtesy of Airbus, modified by NTSB

Improper T-bolt installation and maintenance records were cited by the NTSB as the probable cause in a March 2024 air ambulance accident in Indiana. The Airbus Helicopters BK117C2 sustained substantial damage during a “hard landing” after a critical tail rotor control failure. Two medical crewmembers aboard, as well as the pilot, were not injured in the mishap.

Operating as an air ambulance under Part 135, the helicopter was departing Purdue University Airport (KLAF) in West Lafayette, Indiana, at night when the pilot reported feeling a sudden force on the pedals during a hover taxi. The aircraft began an uncommanded right yaw, and the pilot stated that left pedal input had no effect. Next, the pilot executed an emergency landing.