AAIB Bulletin: 5/2020

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101 © Crown copyright 2020 All times are UTC AAIB Bulletin: 5/2020 G-LLIZ EW/G2019/10/03 ACCIDENT Aircraft Type and Registration: Robinson R44 II Raven II, G-LLIZ No & Type of Engines: 1 Lycoming IO-540-AE1A5 piston engine Year of Manufacture: 2008 (Serial no: 12140) Date & Time (UTC): 2 October 2019 at 1058 hrs Location: Sherburn-in-Elmet Airfield, Yorkshire Type of Flight: Training Persons on Board: Crew - 1 Passengers - None Injuries: Crew - 1 Passengers - N/A Nature of Damage: Beyond economic repair Commander’s Licence: Student Commander’s Age: 34 years Commander’s Flying Experience: 47 hours (of which 2 were on type) Last 90 days - 8 hours Last 28 days - 5 hours Information Source: Aircraft Accident Report Form submitted by the pilot Synopsis A student pilot was on a solo circuit sortie as part of his PPL course. After landing from the third circuit, the pilot noticed that his jacket, which had been secured on the left seat, had moved. In attempting to retrieve the jacket, it is likely that the pilot inadvertently raised the left collective lever. The helicopter pitched up, yawed to the left and rolled onto its right side. The pilot was able to vacate the helicopter but suffered a head injury in the accident. History of the flight The pilot arrived at the airfield to complete a solo circuits flight as part of his PPL training. He was briefed by the supervising instructor and, having completed the external and internal checks on G-LLIZ, he proceeded to start the engine. Whilst the engine was warming up post-start up, the pilot removed his jacket and placed it onto the left seat of the helicopter, using the seat belt to secure it. He also decided to open both the side vents and the nose vent as the carbon monoxide light had illuminated. This is not unusual when the helicopter engine is running for a period whilst stationary. Opening the vents increased the air movement in the cockpit and the light extinguished. Having completed the pre-takeoff checks, the pilot lifted into the hover and proceeded to the centre of the airfield to depart for his first circuit. After landing off the third circuit the pilot realised that his jacket had moved on the front left seat so that it was now resting next to the open vent in the front left door. The pilot 102 © Crown copyright 2020 All times are UTC AAIB Bulletin: 5/2020 G-LLIZ EW/G2019/10/03 was aware of the risks of items striking the tail rotor when sucked out through the open vent in flight so before commencing his fourth circuit he reached out to retrieve the jacket1. Although the pilot does not recall the exact sequence of events, it is likely that the jacket was caught around the left collective lever. As he pulled the jacket, it raised the lever which increased the pitch on the blades and caused the helicopter to pitch nose up. This increase in pitch caused the rear tail stinger to contact the ground. The helicopter then yawed to the left before rolling right, coming to rest on its right side. The sequence is illustrated using snapshots taken from the airfield CCTV shown in Figures 1 to 7. Figure 1 G-LLIZ begins to pitch nose up Figure 2 The tail stinger contacts the ground Footnote 1 Robinson Helicopters Safety Notice SN-30 warns about the risks associated with loose objects in the cabin. Available: https://robinsonheli.com/wp-content/uploads/2015/12/rhc_sn30.pdf [accessed March2020] 103 © Crown copyright 2020 All times are UTC AAIB Bulletin: 5/2020 G-LLIZ EW/G2019/10/03 Figure 3 G-LLIZ begins to yaw to the left Figure 4 G-LLIZ yaws to the left and begins to roll right Figure 5 First blade impacts the ground 104 © Crown copyright 2020 All times are UTC AAIB Bulletin: 5/2020 G-LLIZ EW/G2019/10/03 Figure 6 Second blade impact Figure 7 G-LLIZ comes to rest on its right side The pilot was able to vacate the helicopter via the left door although he had suffered a head injury. The helicopter was damaged beyond economic repair. Figure 8 shows G-LLIZ after the accident. Figure 8 G-LLIZ after the accident 105 © Crown copyright 2020 All times are UTC AAIB Bulletin: 5/2020 G-LLIZ EW/G2019/10/03 Aircraft details The R44 is designed with a centre mounted cyclic control, a collective lever to the left of each front seat, and a set of tail rotor pedals for each front seat. The collective levers also have a twist-grip throttle fitted. The left seat controls may be removed. Although the pilot was flying the helicopter solo, dual controls remained fitted to G-LLIZ. The manufacturer’s standard practice is for the controls to remain fitted unless there is to be a person occupying the left seat who is not a rated helicopter pilot. The manufacturer does not suggest removing the dual controls for student solo sorties. Cyclic and collective controls are fitted with adjustable friction devices. These devices allow the pilot to adjust the amount of force which is required to move the controls. There is no friction device fitted to the tail rotor pedals. The main rotor is two-bladed with a teetering head. The manufacturer states in the pilots’ operating handbook that pilots should not raise the collective to slow the rotor during shutdown as this might cause the blades to ‘flap and strike the tailcone’. If the throttle is at idle and the pilot raises the collective, the energy of the blades may not be sufficient to retain them in their normal range as their pitch increases and it is possible that they may flap beyond the limit, with the retreating blade striking the tailcone. The aircraft checklist requires that all loose articles are removed and stowed as part of the pre-flight checks although the pilot of G-LLIZ removed his jacket after this checklist was complete. Dynamic rollover Dynamic rollover is caused when a landing gear wheel or skid is in contact with a fixed object or the surface which stops the wheel or skid moving sideways. The helicopter can