For the next ten years, the U.S. Air Force is outsourcing much of the maintenance on their fleet of 94 B-52 bombers. Air forces are increasingly turning to civilian firms, to take care of a lot of aircraft maintenance. Contractors can do this cheaper than the air force, because the civilian firms use long-term employees, and have the resources of a major aircraft services company behind them.
The B-52 contract is for $750 million. That comes out to $798,000 per aircraft per year. Called the Engineering Sustainment Program (ESP), the manufacturer of the aircraft, Boeing will be doing the work, which includes maintaining engineering records and performing hardware and software upgrades. The ESP handles investigations for engineering issues, conducting regular, and emergency, testing of aircraft components, and a lot of other items that occur sporadically (but require skilled and experienced people to carry out quickly and correctly.) Air force personnel will still do the regular, day to day, maintenance.
All these aircraft involved entered service in the 1960s. While the first heavy bombers, like the World War II B-17, had a service life of less than 20 years, no heavy bomber design since the 1950s has been effective enough to require retiring the B-52s. It's a relatively inexpensive, reliable and, because of smart bombs and air launched cruise missiles, still effective heavy bomber.