Complex sentence: In 1972, the Army conducted an evaluation between the Bell Model 309 KingCobra, the Lockheed Cheyenne and Sikorsky S-67 in a competitive fly-off, beginning in the spring of 1972 and was completed in July.
Split into simpler sentences: In 1972, the Army conducted an evaluation between the Bell Model 309 KingCobra, the Lockheed Cheyenne, and the Sikorsky S-67 in a competitive fly-off. The fly-off began in the spring of 1972 and was completed in July.