The pilot of G-VSKP had no control over the trail rotor of his aircraft when it crashed at the King Power Stadium, Leicester on 27th October 2018 killing all onboard.
The finding comes from the latest special bulletin from the Air Accidents Investigation Branch (AAIB) who found that the tail rotor control lever had become disconnected from the assembly putting the Leonardo AW169 into a uncontrollable right hand yaw.
The crash, which killed Leicester City Football Club owner Vichai Srivaddhanaprabha along with the pilot, his girlfriend and 2 members of staff, happened shortly after take-off from the pitch.
In a video which was widely shared online the helicopter can be seen carrying out a normal take off procedure before entering a right hand spinning motion, or yaw. The spin quickly accelerates and the aircraft crashed just outside the stadium in a car park.
The special bulletin said that on inspection at the crash site, investigators found that the lever that connected the pilots control pedals to the tail rotor servo was not connected and that “the pin, spacers and one of the locating bearings were missing from the lever” they went on to say that “The locking nut and pin carrier were found loose in the tail rotor fairing and were bonded together (they should be separate components).”
Whilst it is too early to say why, the AAIB said that “Sufficient force and torque had been applied to the castellated nut on the actuator end of the control shaft to friction weld it to the pin carrier and to shear the installed split pin.” which in turn resulted in the pilot not being able to control the tail rotor.
Investigations are still ongoing into the full cause of the accident and work continues to find the cause of why the bearings and control shaft connection failed.
EASA, the European Air Safety group has already issued several directives for operators to carry out urgent inspections of the tail rotor assembly of Leonardo AW169 Helicopters, the latest being on the 30th November 2018 which directed operators to introduce “repetitive inspections of the castellated nut that secures the tail rotor actuator control shaft to the actuator lever mechanism,and the tail rotor duplex bearing”