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BROOMFIELD, Colo. (KDVR) — National Transportation Safety Board (NTSB) investigators are now focusing on a cracked titanium fan blade and maintenance records from an engine on a Boeing 777 that exploded over Broomfield last weekend.

The plane is now parked at a hanger at Denver International Airport. Investigators are collecting pieces of the Pratt and Whitney engine and plane that fell from the sky just minutes after United Airlines flight 328 took off for Honolulu Saturday afternoon.

“We’re going to be deliberate about going through the inspections, through the all maintenance records,” NTSB Chairman Robert Sumwalt said.

He has not released that specific plane’s maintenance records yet, but aviation experts know about the inspections planes undergo every day and every week.

“Before the airplane leaves, usually the first officer does a walk-around of the airplane and looks very closely at those fan blades,” said Eric Jones, a professor and chair of the Aviation Maintenance Science Department at Embry-Riddle Aeronautical University, who spent 18 years maintaining and inspecting commercial airplanes.

“As the time gets longer with the airplane cycles — say the airplane flies for seven days — then you want to do a little more closer inspection of that airplane,” Jones said.

This could include testing the plane’s oil, which can tell a lot about the engines.

Also, planes are scheduled for more intense inspections based on the calendar and flight hours.

If at anytime, anyone notices anything awry with one of the engines, they’re immediately and thoroughly inspected.

“If there are serious concerns about whether that blade is healthy or not, you could then do non-destructive testing,” Jones said. “It’s not going to damage the blade, but you’re going to look even closer at that blade using a dye or even thermal imagery.”

In 2018, another United Boeing 777 with a Pratt and Whitney engine experienced a similar engine failure on the way to Honolulu. Metal fatigue on the fan blade was blamed for that incident.

At the time, the engines were scheduled to undergo thermal acoustic imagery every five years. After, the FAA ordered it to be conducted every 6,500 flight hours.

Now, all Boeing 777 Pratt and Whitney 4000 series engines will undergo that imagery, with the hopes of preventing another catastrophic engine failure.