The Air Accidents Investigation Branch (AAIB) has released its full report on the helicopter crash involving Leicester City F.C owner Vichai Srivaddhanaprabha, who was onboard.
G-VSKP was the Leonardo AW169 helicopter that the owner of the football club possessed as his mode of transport to get to games.
Without further ado, let’s get into it…
Causes of the Helicopter Crash at Leicester City F.C…
In the full report, the AAIB listed the following three causal factors, as well as the following four contributory factors to the crash at the King Power Stadium, home to Leicester City F.C:
- Seizure of the tail rotor duplex bearing initiated a sequence of failures in the tail rotor pitch control mechanism which culminated in the unrecoverable loss of control of the tail rotor blade pitch angle and the blades moving to their physical limit of travel.
- The unopposed main rotor torque couple and negative tail rotor blade pitch angle resulted in an increasing rate of rotation of the helicopter in yaw, which induced pitch and roll deviations and made effective control of the helicopter’s flightpath impossible.
- The tail rotor duplex bearing likely experienced a combination of dynamic axial and bending moment loads which generated internal contact pressures sufficient to result in lubrication breakdown and the balls sliding across the race surface. This caused premature, surface initiated rolling contact fatigue damage to accumulate until the bearing seized.
- The load survey flight test results were not shared by the helicopter manufacturer with the bearing manufacturer in order to validate the original analysis of the theoretical load spectrum and assess the continued suitability of the bearing for this application, nor were they required to be by the regulatory requirements and guidance.
- There were no design or test requirements in Certification Specification 29 which explicitly addressed rolling contact fatigue in bearings identified as critical parts; while the certification testing of the duplex bearing met the airworthiness authority’s acceptable means of compliance, it was not sufficiently representative of operational demands to identify the failure mode.
- The manufacturer of the helicopter did not implement a routine inspection requirement for critical part bearings removed from service to review their condition against original design and certification assumptions, nor were they required to by the regulatory requirements and guidance.
- Although the failure of the duplex bearing was classified as catastrophic in the certification failure analysis, the various failure sequences and possible risk reduction and mitigation measures within the wider tail rotor control system were not fully considered in the certification process; the regulatory guidance stated that this was not required.
Within this, the AAIB has also released a video on its YouTube channel, explaining further how the helicopter with the Leicester City F.C owner onboard crashed:
Overall, the report now concludes the investigation, and all eyes are on Leonardo now to take stock of the accident and make changes based on the eight recommendations made by the AAIB.
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