One of the eight engines powering a Boeing B-52 bomber flying over Minot Air Force Base on Wednesday quite literally fell right off the aircraft.

The unarmed aircraft, which was on a training flight at the North Dakota base, landed safely and none of the crew were injured, an Air Force spokesman told Defense News.

The service has already initiated an investigation into what went wrong. All crew members of a B-52 that crashed in May 2016 escaped without injury, though a 2008 crash killed all six crew members on board.

The B-52 is a long-range, heavy bomber jet aircraft powered by eight Pratt & Whitney engines. It was first introduced in 1955, though it has continually been upgraded and maintained.

The Air Force has just over 75 B-52s still in service today, which are slated to last into 2040, according to Defense News.

The B-21 Long Range Strike Bomber is expected to replace the aging B-52 fleet once it's introduced some time in the mid-2020s.