The U.S. Army's acquisition executive has cleared the planned Chinook Block II upgrade program.

The upgrade program aims to keep the Boeing-made CH-47F and MH-47G fleets in service through the 2020s. The plan, approved by Army acquisition chief Heidi Shyu, includes new or remanufactured airframes for both regular and special forces units. Maj. Gen. Michael Lundy outlined the plan during an Association of the U.S. Army briefing on Thursday.

"It is on track, it's through the [alternative systems review]," Lundy said. "It has been approved as a plan and we're on progress to make that a program of record."

Other planned upgrades in the Block II program include work on the electrical system, rotor system, and transmission. There is not yet a requirement for a new engine, though the program will prime the helicopters for the possibility of changing the engine in the future.

In addition to upgrading the aircraft, Block II will also modify Army Chinooks to align more closely with the MH-47 aircraft used by the Army Special Operations.

"Over time those two have kind of diverged, we are going to converge the design," Col. Rob Barrie told Defense News.

CH-47 Chinooks are designed for transporting troops, artillery and other supporting equipment. The MH-47G variant features more advanced avionics to support Special Operations missions.