In the U.S. military, helicopters are used for many different types of missions; they are used for assault, search and destroy, scouting, transport and resupply. Currently, the Boeing CH-47 Chinook is still the largest helicopter in use by the U.S. Army. It is a tandem rotor, twin engine, heavy-lift helicopter designed to transport artillery, troops, ammunition, fuel and supplies within military theaters of operation.

The legacy of the Chinook began in 1958 and continues today with the CH-47F and MH-47G configurations. According to Boeing, since the introduction of the CH-47, 1,179 aircraft have been built. The new CH-47F is powered by two Honeywell T55-GA-714A turboshaft engines. It is built and assembled at Boeing's production facility in Ridley Park, Pennsylvania. According to Boeing, 19 countries around the world are operating Chinook helicopters.

More Info: en.wikipedia.org