Last Updated Apr 17, 2018 7:21 PM EDT
PHILADELPHIA -- At leastTuesday when a jet engine on Southwest Airlines Flight 1380 apparently failed at 30,000 feet causing damage to the plane and shrapnel . The New York to Dallas flight made an emergency landing in Philadelphia. There were 149 people aboard.
Now investigators are looking into the plane and specifically the popular jet engine used on the Boeing 737 involved in the deadly incident: a CFM56-7B turbofan engine.
Jet engine casings are designed to keep parts from flying off during an engine failure.
"We do know that parts came off of the engine, but those parts may not have been in that section of the engine that is associated with the protection region," National Transportation Safety Board (NTSB) chairman Robert Sumwalt said Tuesday during a press conference.
Retired NTSB board member and aviation consultant John Goglia believes containment rings may have failed.
"Whatever happened inside that engine exceeded that technology and that protection and the pieces came out of the engine at a very high rate of speed," Goglia told CBS News.
Southwest has a good safety record with only 17 major "accidents and incidents" since it began in 1967 -- including a similar engine failure in August 2016.
A flight from New Orleans to Orlando was forced to make an emergency landing in Pensacola after the casing surrounding one of its engines tore away and left a 5-by-16-inch hole just above the wing.
"Maybe they are related to that previous event, maybe they are not. But we need to understand what is going on here," Sumwalt explained.
The type of jet engine is the most widely used jet engine on roughly 6,700 planes since 1997. It's seen as reliable and safe so investigators will be looking for an anomaly.