 The Army issued a cure @-@ notice to Lockheed on 10 April 1969 , citing 11 technical problems , and unsatisfactory progress on the program . The main issues were the half @-@ P hop vibration issue , and the aircraft gross weight exceeding program requirements . In response , Lockheed proposed an " improved flight control system " ( ICS ) to reduce rotor oscillations , and steps for removing excess weight and addressing other minor issues in production helicopters . The Army felt Lockheed 's solutions to the cure @-@ notice issues would delay the program and increase costs . Citing Lockheed 's inability to meet the production timeline , the Army canceled the AH @-@ 56 production contract on 19 May 1969 , but retained the development contract in hopes that the issues could be resolved . 
