The US National Transportation Safety Board (NTSB) is investigating a reported uncontained engine failure on a Delta Air Lines Boeing 757-200 Sept. 5.

Delta flight 1418 had departed Atlanta Hartsfield-Jackson International Airport bound for Orlando, Florida, with 121 passengers and six crew aboard when the incident occurred. The pilots shut down the engine and safely returned to the airport, the NTSB said Sept. 6. There were no injuries.

According to flight tracking site FlightAware, the 757 flew to about 18,200 ft. before leveling off and descending. The flight duration was 28 min.

The aircraft was manufactured in 1991 and powered by two Pratt & Whitney PW2037 turbofan engines, according to the FAA aircraft registry.

Atlanta-based Delta referred questions to the NTSB, but said it had replaced the engine and planned to return the 757 to service Sept. 11.

Pratt did not immediately respond to a request for comment.

On April 17, the pilots of a Southwest Airlines Boeing 737-700 made an emergency landing at Philadelphia International Airport after the aircraft’s left CFM56-7B engine failed, blowing out a window and causing the cabin to depressurize. One passenger was killed, the first fatality suffered by a US-based passenger airline since 2009. The NTSB has scheduled an investigative hearing Nov. 14 to consider that accident.

Another Southwest 737 experienced a CFM56 engine failure in August 2016 during a flight from New Orleans to Orlando; the flight crew landed safety at Pensacola International Airport.

In October 2016, the right GE CF6 engine failed on an American Airlines Boeing 767-300 during its takeoff roll at Chicago O’Hare International Airport. All 161 passengers and nine crew evacuated the aircraft. Twenty-one people were injured, one seriously.

Bill Carey,