What happened
On 5 December 2014, a Robinson R44 II Raven, registration G-HECK, was undergoing pre-flight preparations at Leeds Heliport. The aircraft was positioned on an apron in front of a hangar, situated between a portable building and a parked vehicle.
Upon completing checks, the pilot started the engine and attempted to transition into a hover by increasing collective pitch. As the aircraft lifted off the ground, the pilot experienced intense and unusual vibrations originating from the main rotor system. In an attempt to stabilize the aircraft, the pilot immediately reduced the collective to descend. During this maneuver, the helicopter yawed toward the left, causing the tail boom to collide with the adjacent parked vehicle. The impact resulted in damage to the helicopter's tail surfaces, gearbox, drive, and tail rotor blades, as well as damage to the roof of the vehicle. There were no injuries to the pilot.
The investigation
Investigators reviewed the accident report submitted by the pilot and an engineering report provided by the helicopter operator. The technical examination focused on the main rotor and its associated control systems to identify the source of the reported vibrations. The engineering investigation found no mechanical abnormalities within the main rotor or the control systems that could explain the severe vibrations experienced during the takeoff attempt.