 The Cheyenne program was canceled by the Secretary of the Army on 9 August 1972 . The helicopter 's large size and inadequate night / all @-@ weather capability were reasons stated by the Army for the cancellation . The Cheyenne 's analog and mechanical weapons systems were becoming out of date as new digital systems that were more accurate , faster , and lighter were being developed . The Cheyenne 's unit cost had increased and was likely to increase further if new avionics were incorporated . 
