The National Transportation Safety Board on Monday said a maintenance records group will be formed to investigate the Boeing 777 engine’s history after it failed on United Airlines flight #328 and erupted into flames shortly after takeoff on Saturday.

"Our mission is to understand not only what happened but why it happened so we can keep it from happening again," NTSB chairman Robert Sumwalt said at a Monday evening press conference. .

Asked whether the particular engine had been inspected after another engine failure on a Southwest Airlines flight in 2018, Sumwalt said that was a question that will be answered pending a maintenance group investigation.

Boeing has recommended that airlines ground all 777s with the type of engine that blew apart after takeoff from Denver this past weekend, and most carriers that fly those planes said they would temporarily pull them from service.

FAA Administrator Steve Dickson identified the focus on the stepped-up inspections as hollow fan blades unique to the Pratt & Whitney PW4000 engine model and used solely on Boeing 777s.

Dickson's statement said the conclusion was based on an initial review of safety data and would likely mean grounding some planes.

United Airlines Flight 328 being inspected. .

The NTSB said the cockpit voice recorder and flight data recorder were transported to its lab in Washington so the data can be analyzed