In 1966, the Army awarded Lockheed a contract for ten AH-56 prototypes, but as a stopgap also ordered the less complex Bell AH-1G Cobra as an interim attack aircraft for combat in Vietnam War. The AH-56's maiden flight took place on 21 September 1967. In January 1968, the Army awarded Lockheed a production contract, based on flight testing progress. A fatal crash and technical problems affecting performance put the helicopter's development behind schedule, resulting in the cancellation of the production contract on 19 May 1969. Development of the Cheyenne continued in the hope that the helicopter would eventually enter service.