On 15 September 2013, the pilot of a Robinson R44 helicopter, registered VH-NUZ, was flying passengers on a private scenic flight over the Montgomery Reef and Buccaneer Archipelago area of Western Australia. The pilot had completed several take-offs and landings at that site already on the day.

After a routine landing at the reef, the pilot shut down the engine. The passengers had disembarked and were standing about 20 to 30 m away.

At about 1530 Western Standard Time the pilot, who was the sole occupant, then started the helicopter’s engine and completed the pre-flight checks. When the pilot raised the collective to bring the helicopter into a hover, it suddenly rotated three times while airborne. The pilot could not regain control and elected to land immediately, however the helicopter landed heavily. The pilot shutdown the engine and exited the helicopter.

The direction that the helicopter rotated could not be ascertained by the pilot or witnesses. The pilot and bystanders were not injured but the helicopter sustained substantial damage as a result of the hard landing.

Based on the information provided, the Australian Transport Safety Bureau (ATSB) was unable to determine what led to the loss of control.

During the investigation, the ATSB was made aware that instances of ‘sudden and violent yawing in forward flight’ had occurred on other ‘low time’ R44 helicopters, being attributed to a ‘sticky inlet valve’, with no recurrence after maintenance rectification.

There were no Service Difficulty Reports (SDR) regarding this issue in the Civil Aviation Safety Authority’s SDR database, making it difficult to pursue this line of enquiry.

The ATSB encourages reporting of occurrences to the ATSB and defects to CASA to allow for continued improvements to aviation safety.

Aviaiton Short Investigations Bulletin - Issue 37