What happened
On 27 January 2003, a Robinson R44 helicopter, registration G-NUDE, was performing a private flight from Cabo de Hornos, Chile, toward King George Island, Antarctica. The crew of two was navigating a 440 nm route across the Drake Passage, maintaining a cruise altitude of 7/00 feet with a significant tailwind. As the aircraft approached its destination, the crew encountered sea fog and diverted southwest to attempt landfall.
During this maneuver, the crew experienced vibrations originating from the engine area, followed by a loss of power. To prevent a loss of rotor RPM, the pilot lowered the collective, which induced a steady descent. Shortly after, the oil pressure dropped to zero, the low-pressure warning light activated, and the engine ceased operation. The pilot in the right seat initiated an autorotation while the other crew member prepared the emergency liferaft. At an altitude of approximately 20 feet, the second crew member exited the aircraft into the sea. The helicopter settled onto the water's surface and sank almost immediately.
The investigation
The investigation focused on the mechanical state of the engine and the environmental conditions. It was noted that the aircraft had recently undergone maintenance in Punto Arenas to replace a crankshaft idler gear bolt, following an FAA Airworthiness Directive. However, investigators noted that a failure of this specific bolt would have caused an instantaneous loss of power rather than the gradual reduction experienced by the crew.
Investigators also examined the potential for carburetor icing due to the cold weather conditions. While the pilot reported using carburetor heat to prevent such an occurrence, the possibility remained a factor. Because the aircraft was not recovered from the seabed, a definitive mechanical cause for the engine failure could not be established.
Findings
- The crew successfully executed a ditching procedure, having previously rehearsed for such an event.
- The crew maintained regular position reports via satellite telephone, which aided their eventual rescue.
- The engine failure and subsequent loss of oil pressure led to the loss of the aircraft.
- Survival was complicated by the fact that the liferaft's inflation line became entangled with the helicopter skid, and the crew's survival suits took on water because their hoods were not secured.
- The aircraft was lost to the sea and remains unrecovered.