What happened
On 16 July 2006, a Bell 206B Jet Ranger, registration G-NEWS, was participating in a student pilot's type conversion training at Cambridge Airfield. The flight, which included an instructor and a student, was intended to conclude with an Engine Off Landing (EOL) exercise.
During the maneuver, the student entered autorotation from 700 feet. The instructor, monitoring the controls, confirmed the approach was safe. As the aircraft decelerated, the student raised the collective pitch lever to cushion the touchdown. However, the initial touchdown was heavier and slower than intended, causing the aircraft to bounce approximately 3 to 4 feet into the air.
Upon the second touchdown, the tail strike protector made contact with the ground. The force of this impact caused the tail rotor gearbox to detach and the main rotor blades to strike the vertical stabilizer. The aircraft experienced a brief period of vibration before settling. The crew sustained no injuries, but the aircraft suffered major damage to the airframe, as well as the main and tail rotor blades.
The investigation
Investigators examined the aircraft's maintenance history and the flight's progression. The student had completed several successful training flights in the preceding days. The investigation focused on the mechanics of the touchdown and the potential causes of the heavy impact.
Technical analysis of the wreckage revealed that the tail pylon bent upwards at the attachment point to the fuselage. The tail rotor gearbox had separated, and the main rotor gearbox mounting plate showed evidence of a heavy impact. The investigation also considered the influence of the high-skid landing gear, though it was not determined to be a contributing factor.
Findings
- The primary cause of the accident was a heavy touchdown and subsequent bounce during the engine-off landing.
- It is possible the student provided inadequate collective input to reduce the sink rate, or alternatively, continued to raise the collective after the first impact, contributing to the bounce.
- The investigation considered that windshear, caused by light and variable surface winds combined with high ambient temperatures, may have contributed to the unstable landing.
- The tail-first landing and subsequent contact between the tail rotor blade and the ground or airframe caused the separation of the gearbox.