The Civil Aviation Safety Authority (CASA) has issued an emergency airworthiness directive (AD) grounding all Australian registered Robinson R44 helicopters fitted with main rotor blades carrying the serial number P/N C016-7 (Dash 7) until further notice.
The February 21 AD was the result of initial advice from air crash investigators conducting an investigation into a fatal R44 accident on February 19 near Queenstown, New Zealand. A scene examination has suggested the R44, fitted with Dash 7 blades, may have experienced an in-flight main rotor blade failure.
In January, a R44 flying in New Zealand experienced an in-flight main rotor blade failure, which resulted in severe main rotor vibration. The pilot reported the R44 was difficult to control during the subsequent emergency landing. Upon inspection, the pilot discovered a significant crack emanating from behind the leading edge back beyond the trailing edge.
CASA’s AD allows for helicopters located in remote areas to complete one further flight to the nearest appropriate facility, provided a detailed visual inspection of the blade skin in the region of the outboard chord increase is carried out prior to the flight.
With 485 R44s on the register, CASA said it was unclear exactly how many R44s are fitted with Dash 7 main rotor blades and that it would continue to work closely with Robinson Helicopter, the Civil Aviation Authority of New Zealand and the FAA to examine the cause of the cracking and to resolve the issue.
The grounding comes less than two years after a CASA mandate required all Australian R44s to have their aluminum fuel tanks replaced with a bladder type tank to reduce post-impact fires from occurring. Mid last decade, a number of Robinson’s R22 and R44 types suffered a delamination of their main rotor blade skins, proven to have attributed to several fatal accidents in Australia and around the world.