Consolidated Aeronautics LA4, VH-LAK, Admiralty Gulf (120 km west of Kalumburu), Western Australia, on 11 August 1990

Circumstances:

The sea state for take-off was moderate with a 35 centimetre chop. As the aircraft approached 40 knots, it struck a wave and bounced into the air. When the aircraft settled back onto the water it was yawed to the left, and this caused it to slide sideways into another wave. The engine and its support pylon broke off at the fuselage. The aircraft sank shortly after coming to a stop. All occupants evacuated successfully. The pilot reported that the yaw was probably induced when the left hand float entered a wave. He was unable to realign the aircraft before it collided with the second wave. The force of the impact although it did not feel severe, caused the engine and pylon to break off. The rear seat passenger seated on the left hand side, was injured when the sash seat belt anchor point was torn from the aircraft. The sash seat belt upper anchor points are also the anchor point for the engine pod bracing wires. As the engine pod and support collapsed to the right, the left hand bracing wire and anchor block were pulled from the fuselage, tensioning the left sash belt and pulling the passenger's head into the fuselage structure.

Recommendations:

The Bureau conducted an examination of the seat belt anchor point failure.

1. It is recommended that the Manufacturer redesign the seat belt anchor point so that it is separate from the engine pod bracing wire anchor point