The contract is worth $186 million and calls for six MD 530F aircraft but could reach as many as 54 helicopters over its four-year life.
Provisioning of critical spare parts for the trainers are included in the deal.
"This is a great day for MD and for me," said Lynn Tilton, chairman and chief executive officer of MD Helicopters. "We feel privileged by the opportunity to support the U.S. Army and deeply honored by the significance of the award."
The MD 530F is equipped with the 650 shaft horsepower Rolls-Royce 250-C30 engine and longer main-rotor blades. It is a high-altitude, hot-day performer.
MD Helicopters, Inc. is a leading manufacturer of commercial and military helicopters.
Additional details on the use of the helicopters the Army has purchased for use in Afghanistan weren't disclosed.