On 22 November 1991 at 0912 hours Australian Central Standard Time (Greenwich Mean
Time + 9.5 h), a Bell 214ST helicopter was ditched into the Timor Sea shortly after takeoff
from a floating production facility. The two crew and 15 passengers evacuated uninjured
from the floating helicopter, prior to the right main flotation bag being punctured and the
helicopter capsizing.
The report concludes that at a critical stage of the takeoff, at an altitude of approximately 120 ft
above the sea, one of the engines experienced a high-side speed excursion. This was
followed by an aircraft main rotor speed increase which illuminated a cockpit indication
warning that the aircraft main rotor speed was out of limits.
The captain reacted to what he thought was an engine power loss by lowering the collective,
which is the prescribed response to that situation, thereby unloading the main rotor which
rapidly accelerated to 116.7%. The electrical control unit of the ungoverned engine, sensing
a power turbine overspeed, actuated the fuel sequence valve to shut off fuel to the engine.
As the over speeding engine accelerated, the other engine, while attempting to compensate,
decelerated to idle power because of the lowered collective command. The captain's action
in lowering the collective exacerbated the rapidity of the event, and because of insufficient
aircraft altitude, there was not enough time for the engine still under power to pick up the
load, or for the captain to take further corrective action to avoid a sea ditching.
At the time of the emergency, the captain was demonstrating a takeoff to his co-pilot.