Summary
The helicopter was substantially damaged when it was ditched in the harbour at Darwin, Northern Territory as a result of the tail rotor and the tail rotor gearbox separating from the aircraft in flight. The flight from the oil rig, positioned 227 degrees (M), 137 miles from Darwin, was
uneventful until the helicopter was crossing Darwin Harbour some seven miles from the airport at a
height of 1,000 feet and at a speed of 100 knots. At this point the pilot noticed a slight vibration, lasting
about five seconds, which he was unable to identify. The vibration increased in intensity and there were
three distinct thumps after which the helicopter pitched violently nose down and yawed to the right. The
pilot lowered the collective pitch and brought the helicopter under control. Although the vibration was
less severe he was unable to read any instruments. He transmitted a distress message which was
received and acknowledged by Darwin Tower. The pilot then attempted to apply a small amount of
collective pitch but the vibration became violent. He continued with the auto rotation, armed the
flotation gear, closed the throttles to the flight idle position and the aircraft landed smoothly on the
water with some right yaw. The helicopter turned clockwise in the water through about 240 degrees
before it rolled onto its port side and the main rotors struck the water. Both of the wheel-mounted
flotation units inflated but the one mounted on the left wheel was breached, probably during inflation.
The pilot, after vacating the aircraft, assisted the passengers and all were quickly rescued by nearby
boats. The aircraft remained partially submerged, resting on a sand bar, and was later recovered.
