Julian Bray the aviation expert and broadcaster suggested on BBC Wales earlier today that the initial findings appear to clear the pilot, as the report strongly suggests, a left yaw [turn] foot pedal control actually pitched the helicopter uncontrollably into a maximum right yaw, spiralling the helicopter nose first onto stepped concrete.
Multiple linked mechanical failures and a control rod effectively unscrewing itself in the process added to the complex process. The investigation is being aided by the recovery of the combined voice and data recorder by the AAIB team fitted to this Augusta AW169, and decoded at AAIB Farnborough.
Year of Manufacture: 2016 (Serial no: 69018)
Location King Power Stadium, Leicester
Date & Time (UTC): 27 October 2018 at 1937 hrs
Type of Flight: Private
Persons on Board: Crew - 1 Passengers - 4
Injuries: Crew - 1 (Fatal) Passengers - 4 (Fatal)
Nature of Damage: Aircraft destroyed
Commander’s Licence: Airline Transport Pilot’s Licence (A and H)
Commander’s Age: 53 years
Commander’s Flying Experience: TBA
Last 90 days - 40 hours Last 28 days - 7 hours
Information Source: AAIB Field Investigation
This second Special Bulletin provides information on the findings to date of a detailed examination of the helicopter’s yaw control system.
The control shaft, the locking nut and pin carrier, and the duplex bearing/sliding unit assembly were removed from the wreckage and inspected in detail. 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.
The evidence 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. Disconnection of the control shaft prevented the feedback
Accordingly, it is inappropriate that AAIB reports should be used to assign fault or blame or determine liability, since neither the investigation nor the reporting process has been undertaken for that purpose.
Airworthiness Directive 2018-0241-E dated 7 November 2018 to mandate
On 19 November 2018 the EASA issued AD 2018-0250-E, superseding
AD 2018-0241-E, to require a precautionary one-time inspection of the tail
rotor duplex bearing and, depending on findings, applicable corrective actions. On 21 November 2018 the helicopter manufacturer published Emergency Alert Service Bulletin ASB169-125 for AW169 helicopters, and ASB189-214
for AW189 helicopters, giving further instructions for a one-time inspection
of the tail rotor duplex bearing. The EASA issued AD 2018-0252-E on
21 November 2018, superseding AD 2018-0250-E and mandating this
On 30 November 2018 the helicopter manufacturer published Emergency Alert Service Bulletin ASB 169-126 for AW169 helicopters, and ASB 189-217
for AW189 helicopters, introducing repetitive inspections of the castellated nut
that secures the tail rotor actuator control shaft to the actuator lever mechanism,
and the tail rotor duplex bearing. The EASA issued AD 2018‑0261‑E on
30 November 2018 mandating the repetitive inspections.
The other areas of investigation specified in Special Bulletin S1/2018 will continue, and the AAIB will report any significant developments as the investigation progresses.