History of the Flight
On 14 August 2012 at 1230 UTC, a Robinson R22 Beta helicopter (registration G-BTHI) was conducting an instructional flight with an instructor as the handling pilot. As the helicopter approached Runway 24 at Leicester Airport at approximately 150 to 200 feet agl and 50 kt, the pilot felt severe vibration through the airframe and controls. The vibration was so intense that he could not read any instruments. He instinctively increased airspeed and made a short MAYDAY call. While transmitting, a clutch warning light illuminated, followed immediately by a low rotor rpm light and warning horn. The pilot entered autorotation. Instead of yawing left as expected, the aircraft yawed right despite the application of full left yaw pedal. To avoid passing over a public road, the pilot increased the rate of turn using the cyclic control. The helicopter turned through approximately 280° as it approached the ground. The pilot applied full up collective input to cushion the touchdown, but the aircraft landed heavily with little forward speed and considerable right yaw, then rolled onto its left side. The student exited through the right door and the instructor through the broken front windscreen. Both occupants were treated at the scene for minor injuries.
Pilot's Assessment
The pilot assessed that a tail rotor failure had occurred. Subsequent inspection of the wreckage revealed several findings: the tail rotor drive had failed at the intermediate flex plate coupling, just aft of the clutch actuator; a large quantity of wire, probably the power supply for the anti-collision light, was wrapped around the tail rotor drive shaft; the drive shaft damper assembly within the tail boom had broken from its bracket; and the clutch fuse was found out of its housing (if the clutch fuse fails, the clutch light illuminates). The pilot could not determine whether the drive failed at the intermediate flex plate coupling first or whether the initiating failure was the drive shaft damper assembly separating from its bracket.
Damage
The helicopter sustained substantial damage.