United Airlines has found loose bolts during inspections of its fleet of Boeing 737 MAX-9s, as scrutiny grows of the US plane-maker and its beleaguered narrow-body.

The carrier said: “Since we began preliminary inspections on Saturday, we have found instances that appear to relate to installation issues in the door plug – for example, bolts that needed additional tightening.”

It follows an incident involving an Alaska Airlines Boeing 737 MAX-9 at the weekend which saw a panel blow out at 16,000 feet, causing a rapid depressurisation.

Earlier, the National Transportation Safety Board (NTSB) said it had located the missing door panel.

NTSB chair Jennifer Homendy said Bob, a schoolteacher, had found the panel near his Portland, Oregon home.

“We’re going to go pick that up and make sure that we begin analysing it,” she said.

The NTSB has launched a “Go Team” to Portland to investigate the event involving a Boeing 737-9 MAX during a flight from Portland to Ontario, California.

No serious injuries were reported after the window panel was blown out mid-flight.
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