Construction Will Handle Future 5th?Generation Aircraft Sustainment Operations Hill Air Force Base officials have broken ground on a multi-year project encompassing a $1.24-billion investment in aircraft sustainment. Hill Air Force Base is known as a hub for military aircraft maintenance, and the new project will further expand its capabilities with a full depot-level maintenance complex for F-35 and T-7A aircraft. "Hill Air Force Base has adequate facilities, but with the growing program … adding more modern facilities allows them to execute their full program," said Col. Bob McTighe, commander of the Sacramento District Army Corps of Engineers.