ABOVE: AW169 G-VSKP ‘departed from controlled flight’ on 27 October 2018
The AAIB has released a formal report following its investigation into 2018’s fatal helicopter crash, where a Leonardo AW169 struck the ground adjacent to Leicester’s King Power Stadium; concluding that ‘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’.
After lifting off from the pitch at approximately 20:37 BST, the aircraft began to climb out of the stadium before the pilot – Eric Swaffer – began the transition to forward flight. However, despite ‘the immediate application of corrective control inputs from the pilot,’ a rapidly developing rate of yaw could not be controlled. With the failure of the tail rotor duplex’s bearing rendering ‘effective control of the helicopter’s flightpath impossible’, the AAIB report revealed Swaffer to have said “I’ve no idea what’s going on” moments before the aircraft stuck the ground. Despite four on board believed to have survived the initial impact, all five occupants (including Leicester City owner Vichai Srivaddhanaprabha) lost their lives in an ‘intense post-impact fire’.
During the course of their investigation, the AAIB made eight Safety Regulations to EASA to ‘address weaknesses or omissions identified in the regulations for the certification of large helicopters’ under Certification 29. Under the existing conditions, there were no design or test requirements ‘which explicitly addressed rolling contact fatigue in bearings identified as crtical parts’.
Additionally, the report noted that the helicopter’s manufacturer (Leonardo) had not implemented a routine inspection requirement for critical part bearings removed from service, or shared the load survey flight tests results with the bearing manufacturer ‘in order to validate the original analysis of the theoretical load spectrum’. However, in both cases, the manufacturer was ‘not required to by the regulatory requirements and guidance’.
During the course of the AAIB investigation Leonardo has issued 16 Service Bulletins, while EASA has also published nine Airworthiness Directives for the continued airworthiness of the AW169 and AW189 types. Confirming that safety action has already been taken for these fleets, Crispin Orr, Chief Inspector of Air Accidents, noted: “This was a tragic accident in which five people sadly lost their loves. Our thoughts are with their loved ones, and everyone affected.”
IMAGE: AAIB VIA JML