History of the Flight
Two pilots planned to fly a Robinson R44 helicopter from Cabo de Hornos in Southern Chile to Teniente Marsh Airbase on King George Island, Antarctica. After waiting several days for favorable tailwinds, they departed at 2105 hrs for the 440 nm crossing. The helicopter cruised at 700 feet with a 30 kt tailwind, achieving a groundspeed of 120 kt. Approximately four hours later, approaching King George Island, the pilots observed sea fog ahead and altered course to the southwest to attempt landfall. Shortly after, a vibration emanated from the engine area, accompanied by a reduction in power output. The pilots lowered the collective lever to maintain rotor rpm, resulting in a slow rate of descent. After about 30 seconds at 500 feet, oil pressure dropped to zero, the low oil pressure warning light illuminated, and the engine stopped seconds later.
The pilot in the right seat flew the helicopter in autorotation while the left-seat occupant climbed onto the skid, gathered the liferaft and emergency kit, and jumped into the water at 20 feet above the sea. The helicopter was turned into wind and settled onto the sea surface with zero groundspeed. Rotor blades stopped within seconds, and the remaining pilot jumped into the sea. The helicopter sank almost immediately. Both pilots boarded the liferaft, activated their emergency beacon, and used a satellite telephone to call for help. Six hours later, a Chilean Air Force Twin Otter crew spotted them and directed a Chilean Navy vessel to the scene, which rescued the pilots 10 hours after ditching and transported them to Teniente Marsh Airbase.
Survival Aspects
The pilots had considered the possibility of ditching and rehearsed the scenario that occurred. Every 30 minutes throughout the flight, they reported their position via satellite telephone to the Chilean Coastguard. As the left-seat pilot jumped, the liferaft's self-inflation line tangled around the skid, causing the raft to auto-inflate and separate from the pilot and helicopter. The pilot quickly regained the raft, but it could have drifted away, reducing survival chances in a sea temperature of +2°C. A shorter strap might have reduced entanglement risk.
Both pilots wore survival suits but had hoods down for headsets. During the emergency, they could not don their hoods, and suits took on water through unsealed necks while in the sea. They also struggled to keep the liferaft roof in position as waves broke over them. Much of the rescue wait was spent bailing water, which the pilots believed prevented hypothermia.
Possible Causes
The pilots did not provide details of the fuel carried but stated it was sufficient for the crossing. Their flight plan specified 7 hours 30 minutes endurance. An unmodified R44 with an auxiliary fuel tank carrying a maximum 185 liters of usable fuel would have an endurance of just over 3 hours.
While the helicopter was in Punto Arenas before the flight, a new crankshaft idler gear bolt was installed per FAA Airworthiness Directive AD 2002-23-06, due to failures of original bolts causing immediate loss of magneto drive and subsequent engine failure. The helicopter had flown 16 hours since the bolt change; had that been the cause, the power loss would have been immediate rather than the gradual reduction experienced.
Weather conditions at the time posed a high risk of carburetor icing. The handling pilot reported using carburetor heat to keep the carburetor air temperature out of the avoidance area. The crew did not believe carburetor icing was causing problems at the time of power loss.
The helicopter was not recovered from the seabed, so the cause of this accident cannot be positively determined.