European safety regulators have warned of a potentially unsafe condition with the tail rotor assemblies of Leonardo Helicopters AW169 and AW189 rotorcraft.
Although the move follows the fatal crash of an AW169 in Leicester, UK on 27 October, the emergency airworthiness directive stresses the root cause of that accident "has not been identified".
The Leicester crash occurred "while the helicopter was on a take-off phase at low forward speed" and "a loss of yaw control was observed".
Footage of the AW169's take-off shows its pilot performing a vertical departure before the helicopter develops an uncontrollable spin and crashes to the ground.
Issued by the European Aviation Safety Agency, the directive stipulates that operators of both types must, within five flight hours or 24h, inspect the tail rotor servo-actuator installation.
On 6 November, the manufacturer issued an emergency service bulletin advising operators of the AW169 to check the installation and functioning of the same component.
"Incorrect installation may lead to loss of tail rotor control which, depending on the flight condition, could lead to loss of control of the aircraft," the bulletin warns.
No safety issues have so far been detected with the larger AW189 super-medium-twin, but EASA notes that it is included in the directive as its tail rotor control system is "of a similar design" to that on AW169.
The UK Air Accidents Investigation Branch has yet to release any information related to the cause of the Leicester crash.
Leonardo Helicopters describes the service bulletins for both types as "precautionary", adding that "any hypothesis on the cause of the accident is premature at this time and the AAIB investigation continues".