The U.S. Air Force introduced its first fully built HH-60G Pave Hawk Operational Replacement helicopter during a ceremony Tuesday in Hunstville, Ala.

The Pave Hawks are refurbished Army Black Hawk helicopters. The program aims to restore a Pave Hawk fleet lost in the nearly 15 years of combat operations since Sept. 11, 2001, the service said.

Pave Hawks are used to conduct combat search and rescue operations.

The Air Force acquired 21 Army Black Hawks and added a comprehensive modification kit and additional equipment.

The Black Hawks were well-maintained, structurally sound aircraft with no systemic maintenance problems, the Air Force said.

The Air Force worked with the Army's Aviation and Missile Command to modify the Black Hawks as part of an effort that began in 2012.

It required folding 30 years of Pave Hawk modifications into a single technical data package.

Air National Guard units are slated to begin receiving the repurposed helicopters in Fiscal 2018.