Analysis, Design, and Testing of Fuselage Tuning for the CH-47 Chinook

Recent advances in computers and software have improved the tools required to analyze fuselage dynamic response for existing helicopters and design optimized structural tuning. The U.S. Army and The Boeing Company entered into a Cooperative Research & Development Agreement (CRDA) to retune the structure of a CH-47D ‘Chinook’ to reduce the 3P airframe vibration and associated strain. Under this program a rapid prototyping process was employed to develop and shake test a proof-of-concept airframe. The retuned aircraft was then flight tested at Cairns Army Airfield, Fort Rucker, Alabama using a joint test team of The Boeing Company, U.S. Army Aviation Technical Test Center (ATTC), and U.S. Army Aviation and Missle Command (AMCOM). After successful completion of the 3P tuning, additional airframe modifications, to reduce the cockpit 6P vibration, were installed and successfully flight tested at Fort Rucker under the supervision of the joint test team. These two modifications produced significant reductions in 3P and 6P cockpit vibration and 3P aft pylon stress.