The Australian Transport Safety Board has blamed the fatal crash of a Robinson R44 at Cessnock Airport last year on a detached control system fastener.
After doing a simulated hydraulic failure as part of a flight review, the pilot and instructor were unable to re-engage the hydraulic system. With another passenger on board, the instructor tried to reposition the R44 so the system could be checked out.
Shortly after take-off, the helicopter went out of control and crashed heavily near the runway. The pilot was able to escape, but the instructor and the passenger died in the ensuing fire.
It was later discovered that a fastener in the control system had become detached and this gave similar effects to a failed hydraulic system. Robinson reported no other instances of this type of failure occurring.
The fire completely engulfed the aircraft when the aluminium fuel tank ruptured. Robinson had released a service bulletin requiring all R44s to be fitted with bladder tanks before December 2014, but the accident aircraft had not been converted at the time of the crash.
The full report is available on the ATSB website.