In 1964, U.S. Army lunched the AAFSS specification, that calling for an aircraft with a high-speed cruising and long-time hovering capability. Sikorsky submitted the S-66 pusher tail rotor project that competitor with Lockheed AH-56 Cheyenne. The AH-56 won the contest but failed to meet the expectations. For intended to replace the AH-56, Sikorsky self-venture developed a simplified AAFSS
that used a number of existing components to complete the S-67 Blackhawk.
It was not only designed as a attack helicopter, but also served for other
missions as troop transport, armed rescue and anti-submarine warfare.
Sikorsky proposed the S-67 to U.S. Army as the AH-3 and later for the new
AAH competition but never chosen for the fly-off. Flight test started by Sikorsky's test pilots in 1970, it
established helicopter world speed record 220.89 mph in the same year. In
1971, U.S. Army joined the evaluation program but it was judged
unsatisfactory to meet the new competition. S-67 was finally destroyed in
crash at 1974 Farnborough air show.