What happened
On 28 December 2013, a Rotorsport UK MTOsport, registration G-PAFF, was involved in an incident at Graveley Airfield in Hertfordshire. The pilot had completed several flights earlier that afternoon and had repositioned the aircraft for a subsequent takeoff immediately following a previous landing.
As the pilot applied full throttle and pulled the control column rearward, a significant jolt was felt through the flight controls. Recognizing the abnormality, the pilot aborted the takeoff and brought the aircraft to a stop. A subsequent inspection revealed that the rotor blades had made contact with the top of the rudder, resulting in an indentation on the rotor blades and a split at the rudder tip. There were no injuries to the pilot and no other damage was noted on the aircraft.
The investigation
The AAIB investigation focused on the mechanical and operational factors leading to the contact between the rotor disc and the tail unit. The investigation examined the pilot's actions and the state of the aircraft's rotor speed prior to the incident.
It was established that the pilot had not checked the rotor RPM gauge before initiating the takeoff sequence. The pilot estimated that the rotor speed was between 120 and 140 rpm, which is significantly below the minimum required speed of 200 rpm for takeoff. Additionally, the pilot was not utilizing the rotor pre-rotator at the time of the incident.