V-22 Osprey Qualification Testing Leading to Flight in Known Icing Conditions

The V-22 Osprey is a tiltrotor aircraft capable of vertical takeoff and landing (VTOL). Like a rotorcraft it can hover or cruise like a turboprop airplane. The program full-scale development (FSD) contract was awarded in 1985 by the Government. The aircraft requirements included at the initial stage of the program the capability for the aircraft to fly in known icing conditions. The integration of an ice protection system in a tiltrotor aircraft provided many challenges, which were addressed by early technology risk reduction testing at the system component level. Safety-of-flight testing followed once the necessary technologies had been selected and the design finalized. The ice protection system as whole was tested as further risk reduction behind the NKC-135 icing tanker to validate mostly nacelle ice protection and behind the Helicopter Icing Spray System to investigate the performance of the rotor deicing system. All these tests allowed the aircraft to proceed with testing in natural icing conditions. Three full seasons of natural icing tests throughout all conditions, flight modes, and failure combinations conclude the qualification of the aircraft ice protection system. The presentation is a top-level description of the testing involved in obtaining a flight clearance for operation in known icing.