Maintenance.
Not Boeing this time.
Why would someone go in there? Oil, magnetic plugs, filter change....
Some idjit didn’t close the cowl properly. Not a difficult task. Done plenty.
This never would have happened on Herb Kellerher’s watch.
No worse than your mechanic not closing the hood after an oil change, only at 550 mph and 3,000 ft, instead of 60 on the freeway.
At least the engine cover doesn’t block your view...