United Airlines found loose bolts, other issues on a key part of grounded Boeing 737 Max 9 jetliners

United Airlines found loose bolts and other installation issues on a part of some Boeing 737 Max 9 jets that were inspected after a mid-flight blowout. Photo / Getty Images

United Airlines says it found loose bolts and other “installation issues” on a part of some Boeing 737 Max 9 jets that were inspected after a mid-flight blowout on a similar Alaska Airlines jet on Friday.

The inspections are focused on plugs used to seal an area set aside for extra emergency doors that are not required on United and Alaska Max 9s.

“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,” Chicago-based United said.

The Federal Aviation Administration grounded all Max 9s operated by Alaska and United and some flown by foreign airlines after a terrifying flight on Friday night.

Alaska Airlines had already decided not to use the Boeing on flights to Hawaii after a warning light lit up on three different flights. It wanted to avoid long flights over water so it could return quickly to an airport if necessary. Photo / Twitter

The Boeing jetliner that suffered an inflight blowout over Oregon was not being used for flights to Hawaii after a warning light that could have indicated a pressurisation problem lit up on three different flights.

Alaska Airlines decided to restrict the aircraft from long flights over water so the plane “could return very quickly to an airport” if the warning light reappeared, Jennifer Homendy, chair of the National Transportation Safety Board (NTSB), said on Sunday.

She cautioned that the pressurisation light might be unrelated to Friday’s incident in which a plug covering an unused exit door blew off the Boeing 737 Max 9 as it cruised about 5 kilometres over Oregon.

On Monday, the FAA approved guidelines for inspecting the door plugs on other Max 9 jets and repairing them, if necessary. That move could speed the return to service of the 171 grounded planes.

Alaska has 64 other Max 9s and United Airlines owns 79. No other US airlines operate that model of the Boeing 737.

Shares of The Boeing Co fell 8 per cent and those of Spirit AeroSystems, which builds the fuselage for Boeing’s 737 Max, tumbled 11 per cent on Monday, the first day of trading since the accident. Shares of Alaska Airlines were nearly unchanged after slumping earlier in the session.

The auto-pressurisation system warning on the Alaska Airlines jet lit up during three previous flights. Homendy said she didn’t have details about an incident on December 7, but said it came on again during a flight on January 3 and after the plane landed on January 4 – the day before the blowout.

“We plan to look at that more, and we’ve requested documentation on all defects since delivery of the aircraft on October 31,” she said.

The lost door plug was found near Portland, Oregon, in the backyard of a home. Photo / AP

The NTSB said the lost door plug was found on Sunday near Portland, Oregon, in the backyard of a home. Investigators will examine the plug, which is 66 centimetres by 121cm and weighs 28.5 kilograms, for signs of how it broke free.

What to know

• A door “plug” may provide key information to explain how the blowout happened.
• Boeing faces new scrutiny about the safety of its best-selling plane.
• This is not the first incident to have raised questions about the safety of Boeing’s 737 Max jets.

Investigators will not have the benefit of hearing what was going on in the cockpit during the flight. The cockpit voice recorder – one of two so-called black boxes – recorded over the flight’s sounds after two hours, Homendy said.

At a news conference on Sunday night, she provided new details about the chaotic scene that unfolded on the plane. The explosive rush of air damaged several rows of seats and pulled insulation from the walls. The cockpit door flew open and banged into a lavatory door.

The force ripped the headset off the co-pilot and the captain lost part of her headset. A quick reference checklist kept within easy reach of the pilots flew out of the open cockpit, Homendy said.

Two cell phones belonging to passengers on Friday’s flight were found on the ground. Photo / Sean Bates

Two cellphones that appeared to have belonged to passengers on the flight were found on the ground. One was discovered in a yard, the other on the side of a road. Both were turned over to the NTSB.

The plane made it back to Portland and none of the 171 passengers and six crew members was seriously injured.

Hours after the incident, the FAA ordered the grounding of 171 of the 218 Max 9s in operation, including all those used by Alaska Airlines and United Airlines, until they can be inspected. That led to flight cancellations at both carriers.

Early on Monday, Alaska Airlines was forced to cancel 20 per cent of all flights, 141 in all. United cancelled 221 flights, or 8 per cent of its total flights scheduled for Monday.

Boeing chief executive Dave Calhoun called a company-wide webcast to talk about the incident with employees and senior leadership.

“When serious accidents like this occur, it is critical for us to work transparently with our customers and regulators to understand and address the causes of the event, and to ensure they don’t happen again,” he wrote in a message to employees on Sunday. “This is and must be the focus of our team right now.”

The chunk of fuselage blew out as the plane was climbing at about 16,000 feet. Photo / Twitter

Alaska Airlines flight 1282 took off from Portland at 5.07 pm Friday for a two-hour trip to Ontario, California. About six minutes later, the chunk of fuselage blew out as the plane was climbing at about 16,000ft (4.8 kilometres).

One of the pilots declared an emergency and asked for clearance to descend to 10,000ft, where the air would be rich enough for passengers to breathe without oxygen masks.

Videos posted online by passengers showed a gaping hole where the door had been. They applauded when the plane landed safely about 13 minutes after the blowout. Firefighters came down the aisle, asking passengers to remain in their seats as they treated the injured.

It was extremely lucky that the plane had not reached cruising altitude when passengers and flight attendants might have been walking around the cabin, Homendy said.

The aircraft involved left the assembly line and received its certification two months ago, according to online FAA records. It had been on 145 flights since entering commercial service on November 11, said tracking service FlightRadar24. The flight from Portland was its third of the day.

The Max is the newest version of Boeing’s venerable 737, a twin-engine, single-aisle plane used frequently on US domestic flights. The Max entered service in May 2017.

Two Max 8 jets crashed in 2018 and 2019, killing 346 people. All Max 8 and Max 9 planes were grounded worldwide for nearly two years until Boeing made changes to an automated flight control system implicated in the crashes.

The Max has been plagued by other issues, including manufacturing flaws, concern about overheating that led the FAA to tell pilots to limit the use of an anti-ice system, and a possible loose bolt in the rudder system.