The Air Accidents Investigation Branch have revealed the cause of the helicopter crash that claimed the lives of five people, including Leicester City chairman and owner Vichai Srivaddhanaprabha.
The helicopter picked Srivaddhanaprabha up in the centre of the pitch at Leicester's King Power Stadium after their game against West Ham, as it often did, and took off before losing control shortly after and crashing down in a car park just outside the stadium before becoming engulfed in flames.
The other four victims were Srivaddhanaprabha's staff Nursara Suknamai and Kaveporn Punpare, as well as pilot Eric Swaffer and his partner Izabela Roza Lechowicz.
The report explains that a pin had come loose due to a "build-up of black grease", causing the pilot's pedals to become unable to control the tail rotor, leading to a loss of control of the aircraft and subsequent crash.
"The tail rotor actuator control shaft became disconnected from the actuator lever mechanism," the report stated.
"The disconnection stopped the feedback mechanism for the tail rotor actuator from operating and the tail rotor actuator from responding to yaw control inputs.
"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.
"Whilst the shaft was rotating and a yaw control input was applied, the shaft 'unscrewed' from the nut, disconnecting the shaft from the actuator level mechanism, and causing the nut to become welded to the pin carrier."
The helicopter picked Srivaddhanaprabha up in the centre of the pitch at Leicester's King Power Stadium after their game against West Ham, as it often did, and took off before losing control shortly after and crashing down in a car park just outside the stadium before becoming engulfed in flames.
The other four victims were Srivaddhanaprabha's staff Nursara Suknamai and Kaveporn Punpare, as well as pilot Eric Swaffer and his partner Izabela Roza Lechowicz.
The report explains that a pin had come loose due to a "build-up of black grease", causing the pilot's pedals to become unable to control the tail rotor, leading to a loss of control of the aircraft and subsequent crash.
"The tail rotor actuator control shaft became disconnected from the actuator lever mechanism," the report stated.
"The disconnection stopped the feedback mechanism for the tail rotor actuator from operating and the tail rotor actuator from responding to yaw control inputs.
"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.
"Whilst the shaft was rotating and a yaw control input was applied, the shaft 'unscrewed' from the nut, disconnecting the shaft from the actuator level mechanism, and causing the nut to become welded to the pin carrier."
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