United Airlines Finds Loose Bolts on Some Boeing 737 MAX 9 Jets

United Airlines said it found loose bolts on some of the Boeing 737 MAX 9 jets in its fleet, a discovery that the manufacturing problems go beyond a near-catastrophe with a flight Friday.

U.S. air safety officials grounded the Boeing jets and are still investigating what caused an emergency-door plug to detach from an Alaska Airlines plane flying at 16,000 feet, leaving it with a gaping hole.