What happened
On 7 April 2007, an AS355F2 Twin Squirrel, registration G-CAMB, was engaged in a type conversion training flight at Shobdon Airfield, Herefordshire. The flight was being conducted by an instructor and a student pilot who was nearing the completion of the conversion process.
During the session, the crew performed a departure procedure that included a simulated engine failure. Following the simulated failure, the helicopter was intended to land straight ahead. However, the takeoff was rejected. During this aborted manoeuvre, the helicopter lost forward airspeed at an altitude of approximately 8 feet. As the speed decreased, the aircraft experienced a reduction in translational lift, which prevented the remaining engine from maintaining the necessary torque to stop the descent rate. This led to a hard landing where the aircraft struck the right skid before bouncing across the landing area and finally settling on both skids. The damage, consisting of crease damage to the forward section of the tail boom, was identified during a post-flight inspection.
The investigation
The investigation examined the flight sequence and the mechanical response of the aircraft. The crew reported a slight yaw during the landing phase, which was attributed to the torque effects caused by the instructor restoring power to the simulated failed engine. The commander assessed that the landing was not excessively hard, despite the resulting structural damage.
Findings
- The primary cause of the hard landing was the loss of sufficient torque to arrest the rate of descent following the reduction in translational lift.
- The crew sustained 1 minor injury (delayed whiplash) to the instructor.
- The aircraft sustained crease damage to the forward end of the tail boom.