What happened
On 30 October 2006, a Robinson R22 Beta, registration G-OLIZ, was performing a private local flight from a private helipad in Whitley, Dewsbury. The flight began with a normal engine start and a warm-up period of approximately ten minutes. Following standard procedures, the pilot checked the carburettor heat and applied partial heat before taxiing backwards to extend the takeoff run. The pilot planned a north-easterly departure to avoid nearby buildings, utilizing near-maximum power to clear a line of trees standing roughly 25 feet high.
As the aircraft cleared the trees at an airspeed of approximately 25 kt, the engine began to splutter. The pilot responded by pulling on the collective control and switching off the rpm governor while simultaneously applying full carburettor heat. Upon hearing the low rpm horn and observing the helicopter yawing to the right, the pilot believed an engine failure had occurred. At an altitude of only 30 to 40 feet, the pilot initiated a forced landing into a group of trees to cushion the impact. The aircraft struck a large tree, rotated approximately 180 degrees, and came to rest on its right side. The pilot sustained minor injuries, but the helicopter suffered extensive damage.
The investigation
The investigation examined the sequence of events leading to the impact and the pilot's subsequent actions. Investigators looked into the engine's performance during the climb and the pilot's decision-making process regarding the low rpm warning. The post-accident assessment confirmed that no engine malfunction had occurred prior to the impact. The pilot later noted that the initial engine instability might have been caused by carburettor icing, and that his attempt to compensate by increasing collective input likely contributed to the drop in rotor rpm.
Findings
- The pilot's decision to increase collective input in response to the engine spluttering caused a reduction in rotor rpm.
- The combination of low airspeed and low altitude left the pilot with no viable options for a controlled landing outside of the tree area.
- The pilot's reaction to the low rpm horn and the yawing motion led him to believe the engine had failed, prompting the immediate descent.