Demo
    Black and white photo of a large aircraft's underbelly showing its three sizable jet engines. A person stands near the engines, seemingly inspecting them, against a backdrop of a partly cloudy sky.
    A U.S. airman checks the eight J57 engines on a B-52 at Tinker Air Force Base, Okla., in the late 1950s. The Air Force shifted to TF33 turbofan engines for today's B-52H versions that began flying in operations in 1961.
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    A group of people in military uniforms perform maintenance on the undercarriage of an aircraft.
    U.S. airmen look for leaks from a B-52 Stratofortress’ running TF33 engines. In-depth inspections like this one at Barksdale Air Force Base, La., are required after every 450 flying hours. The Air Force estimates the engines will be "unsustainable" by 2030.
    Two people in military uniforms work on an aircraft engine mounted on a stand inside a maintenance facility.
    U.S. Air Force aerospace propulsion technicians practice repairs on a trainer B-52 engine at Barksdale Air Force Base, La.