The Australian Transport Safety Bureau is advising operators of Robinson R44 helicopters to check their hydraulic boost servos following a fatal accident earlier this year when part of a helicopter's flight controls separated from the hydraulic-boost system.
The R44 was performing circuit operations at Cessnock aerodrome in New South Wales with an instructor, a pilot undergoing a helicopter flight review and a passenger.
The hydraulic system failed following the completion of a sequence involving the simulated failure of the hydraulic-boost system. The pilot lost control of the aircraft as he was trying to reposition it for further examination.
The helicopter collided with the runway and the R44 caught fire. The pilot survived the accident but the instructor and passenger died. The safety bureau found that a bolt securing part of the flight-control system had detached, prompting its recommendation to inspect and test the security of the flight-control attachments, paying particular attention to the connections at the top and bottom of the servos. The bureau is continuing its investigation.