Flight-Test Report on the Heavy-Lift Helicopter Flight-Control System

The U.S. Army's Heavy-Lift Helicopter must be able to pick up and fly efficiently with its external loads in all weather conditions, including instrument meteorological conditions. The design objectives for the flight-control system include improved reliability and survivability, as well as the capacity for precise hover maneuvering. A redundant, electrical, fly-by-wire control system replaces the conventional mechanical controls and accepts limited-authority signals from a digital automatic-flight-control system (AFCS). The AFCS provides stability-and-control augmentation and pilot-selectable, mission-related modes. Critical elements of the control system were flight-tested for feasibility in a highly modified CH-47 Chinook helicopter, formerly known as the Boeing Vertol 347. The objectives and results of the test program are discussed, with emphasis on the operational load-handling capability.