Leicester City owner Vichai Srivaddhanaprabha was among four people who died in the crash on October 27
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.
“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.”
The report adds that burnt-on grease was discovered on a key part of the control system at the crash site.
“The locking nut on the bearing end of the control shaft was found to have a torque load significantly higher than the required assembly value.
“The inner races of the bearing could only be rotated a few degrees in either direction by hand.
“There was a build-up of black grease inside the slider unit around the inboard face of the duplex bearing.
“The section of the control shaft adjacent to this bearing face showed evidence of burnt-on grease and was discoloured along its length.”
Safety checks were ordered on helicopters of a similar design to the AugustaWestland AW169 in light of the tragedy.
The European Aviation Safety Agency (EASA) issued the Airworthiness Directive focusing on the tail rotor of the helicopter. It has been confirmed the AW169 has not been involved in any recorded accidents before.
Foxes keeper Kasper Schmeichel was among the witnesses to the tragedy, which devastated the footballing world and led to an outpouring of tributes from fans and clubs across the country.
As a close friend of Srivaddhanaprabha and the last player to see him alive, Schmeichel has felt the impact of the crash as much as anyone.
Schmeichel said: “I was on the pitch, I waved him off, I saw it all happen.
“It was something that will stay with me, unfortunately.
“It is not a nice memory but the club have been great and everybody has received the support they needed. I spoke to somebody.”
The investigation into the initiating cause and exact sequence of the failure continues as a priority.