B-52 Stratofortress strategic bomber arrived at Tinker Air Force Base for induction to major overhaul by the Oklahoma City Air Logistics Complex after a ferry flight from San Antonio, Texas.

The complex performs programmed depot maintenance on the C/KC-135, B-1B, B-52 and E-3 aircraft; and maintenance, repair and overhaul engines for the Air Force, Air Force Reserve, Air National Guard, Navy and foreign military sales.

The aircraft, with the serial number 61-001 was flown gear-down by a crew from the 10th Flight Test Squadron, Air Force Reserve Command, from Boeing’s facility after receiving ‘milk-bottle’ replacements to extend the service life of the aircraft by replacing the wing-attachment points.

The project, called the ‘milk-bottle’, covers inspection and retrofit the center wing sections to alleviate metal fatigue.

A program used very largely connecting pins, sized and shaped like a milk bottle, eventually resulting in the name “milk-bottle”.

The U.S. Air Force’s website said the for more than 60 years, B-52s have been the backbone of the strategic bomber force for the United States.

The B-52A first flew in 1954, and the B model entered service in 1955. A total of 744 B-52s were built, with the last, a B-52H, delivered in October 1962. The first of 102 B-52H’s was delivered to Strategic Air Command in May 1961. The H model can carry up to 20 air-launched cruise missiles. In addition, it can carry conventional cruise missiles that were launched in several contingencies starting in the 1990s with Operation Desert Storm and culminating with Operation Inherent Resolve in 2016.