AeroServoElastic Test Campaign of the AW609 Civil Tilt-Rotor

Part of the certification process of the Leonardo Helicopters AW609 – the first tiltrotor that is undergoing a civil certification process – is demonstrating that the aircraft is free from any aeroservoelastic instability by both analysis and flight test. Recently, one of the AW609 prototypes underwent an extensive certification flight flutter and ground stability test campaign. During these tests, the fundamental aircraft flutter mechanisms have been excited and demonstrated to meet the required stability margins foreseen by the certification basis. In this paper, the test methodology used to perform the tests and flight data processing techniques are detailed. The results are then presented in terms of frequency and damping and as a function of aircraft parameters such as airspeed and gross weight. The certification test results successfully establish that the AW609 is free from instability across the flight envelope and operating conditions with no detrimental damping trends.