A 30cm pin caused the catastrophic helicopter crash which killed Leicester City owner Vichai Srivaddhanaprabha and four others.
The Thai billionaire, two members of his staff, Nusara Suknamai and Kaveporn Punpare, pilot Eric Swaffer and another passenger, Izabela Roza Lechowicz, all lost their lives on Saturday October 27.
Khun Vichai’s aircraft, a £6.7million 2016 Augusta AW169, spiralled out of control shortly after take off.
The helicopter came down in a car park near the stadium just over an hour after Leicester had drawn 1-1 against West Ham United in the Premier League, erupting into flames.
According to the Air Accidents Investigation Branch, a mechanism linking the pilot’s pedals with the tail rotor blades became disconnected.
The eight-page report concluded the failure of the rotor caused the helicopter to violently veer to the right which led to it crashing in a fireball and being completely destroyed.
“The evidence gathered to date shows that the loss of control of the helicopter resulted from the tail rotor actuator control shaft becoming disconnected from the actuator lever mechanism,” declared the special report. from the AAIB.
“Disconnection of the control shaft from the lever prevented the feedback mechanism for the tail rotor actuator from operating and the tail rotor actuator from responding to yaw control inputs.
“Loss of the feedback mechanism rendered the yaw stops ineffective, allowing the tail rotor actuator to continue changing the pitch of the tail rotor blades until they reached the physical limit of their travel. This resulted in an uncontrollable right yaw.
“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.
“The observed condition of the duplex bearing and the increased torque load on the castellated nut that remained on the spider end of the shaft is consistent with rotation of the tail rotor actuator control shaft.
“Whilst the shaft was rotating and a yaw control input was applied, the shaft “unscrewed” from the nut, disconnecting the shaft from the actuator lever mechanism, and causing the nut to become welded to the pin carrier.”