What happened
On 22 July 2021, a Robinson R44 II, registration G-OPDG, was performing a private flight from Dromore to Maghera, County Londonderry. The pilot was flying the aircraft to evaluate it for a potential purchase. The flight proceeded normally until the final stages of the approach to a grass landing area.
As the helicopter descended to approximately 30 ft agl with an airspeed of 15 kt, the pilot attempted to arrest the descent by increasing aft cyclic and raising the collective. During this maneuver, a low rotor RPM warning light illuminated and the warning horn sounded. The pilot subsequently attempted to manage the low RPM while simultaneously maneuvering the aircraft to avoid a nearby tree stump. During the descent, the helicopter's tail boom struck a wooden fence, causing the aircraft to yaw right toward an adjacent building. The main rotors then struck the structure, resulting in the aircraft being damaged beyond economic repair. The pilot escaped the crash without injury.
The investigation
The investigation examined the flight path recorded by a GPS application on a tablet and reviewed the pilot's actions during the critical seconds of the descent. Investigators looked into the mechanical state of the aircraft, noting that the helicopter had only flown six hours since its most recent 50-hour maintenance check. The investigation also assessed the landing site, which was bounded by a 1.5 m high fence and a low-rise building, as well as the presence of a large tree stump near the landing area.