What happened
On 8 May 2005, a Robinson R44, registration G-SYTN, was performing a private flight at Swansea Airport. After completing two circuits on Runway 28, the pilot began hover taxiing towards the apron at a north-easterly heading. During this maneuver, the aircraft was subject to a moderate tailwind of approximately 14 knots.
As the pilot transitioned from the taxiway onto the apron, they initiated a right turn. During this turn, the helicopter developed an uncommand to the right that the pilot could not arrest. Despite applying full left pedal input, the aircraft continued to yaw right, causing the nose to pitch down and the main rotor to strike the ground. The impact caused the tail to break off and the main rotor to be destroyed. The aircraft came to rest on its left side, though no fire occurred. The pilot and two passengers were able to exit the aircraft; one passenger was briefly caught by clothing but escaped without major injury.
The investigation
The investigation focused on the cause of the uncommanded yaw and the aircraft's mechanical condition. Engineers performed an inspection of the aircraft and found no evidence of a pre-existing mechanical fault that could have caused the incident. The investigation also reviewed the environmental conditions, noting the presence of a light quartering tailwind during the hover taxi.
Findings
- The aircraft was hover taxiing in a light quartering tailwind.
- The pilot initiated a right turn, which, combined with the wind conditions, created an environment conducive to loss of tail rotor effectiveness (LTE).
- The pilot was unable to maintain directional control, leading to an uncommanded yaw that could not be corrected before ground impact.
- The tail rotor was not stalled, and the primary cause was the loss of effectiveness due to the specific wind and maneuver combination.