Collision with terrain involving a Robinson R22 Beta, VH-JDB, 139 km south-east of Katherine, Northern Territory, on 24 November 1997

In a report to the Bureau the operator advised that the pilot was ferrying the Robinson R22 helicopter from Darwin to Katherine for maintenance when the pilot heard an unusual noise and decide to land to carry out an inspection. The helicopter was landed in a clearing 135 km south-east of Darwin but no obvious defects were found. The operator advised that shortly after taking off to continue the flight the noise was again evident, but worse. The helicopter crashed while attempting a precautionary landing.

Another agency involved with the occurrence was informed that the pilot felt a vibration while in flight and landed to investigate. He carried out a walk round inspection with the engine running and rotors turning but found nothing untoward. During the subsequent take-off he had to clear a knoll some 300ft high approximately 150m ahead. The pilot claimed there was no vibration evident during lift off and in hover, but as he accelerated there was a loud crack and from then on, he was unsure of the events that followed.

The BASI investigation was unable to have the pilot respond to a request for additional clarifying information, nor did the pilot return telephone calls.

A strip down examination of the helicopter failed to disclose any mechanical problem that may have resulted in the symptoms reported by the operator and the pilot. The personnel who recovered the helicopter found evidence that the tail rotor blades had impacted shrubs, most probably as the helicopter departed the clearing.

The investigation was not able to establish why the pilot had landed in the clearing.