UNITED Airlines said yesterday it had discovered loose bolts on Boeing 737 MAX 9 planes in its fleet during preliminary inspections following an Alaska Airlines mid-flight incident.

United has “found instances that appear to relate to installation issues in the door plug – for example, bolts that needed additional tightening”, the carrier said.

On January 5, an Alaska Airlines passenger plane made an emergency landing after the door plug component blew out.

“We’re working to return our Boeing 737 MAX 9s to service in the days ahead,” United said in a statement.

It said it has cancelled 200 MAX 9 flights since the incident and expects “significant cancellations” today.

A door plug is a cover panel used to fill an unneeded emergency exit in planes with smaller seat configurations.

Following the Alaska Airlines incident, the Federal Aviation Administration (FAA) ordered operators to ground 171 jets with the same configuration.

US investigators continued to probe into the incident, but analysts posited the fault might have stemmed from a manufacturing or quality control defect.

With 79 MAX 9 planes, United has the largest fleet of the aircraft in question.

Yesterday, the FAA announced its approval of a roadmap for carriers to complete inspections on both left and right door plugs, components and fasteners.

However, United said it was still awaiting final approval on the full inspection process.

In December, Boeing urged airlines to undertake additional inspections to check for loose hardware on the plane rudder control system after an international operator discovered a bolt with a missing nut while performing routine maintenance. – AFP, January 9, 2024.