The Federal Aviation Administration on Wednesday said it would not allow Boeing Co. to expand production of its Max airplanes after an in-flight blowout this month grounded dozens of them for inspections, and it said it would investigate the jet maker’s compliance with manufacturing protocols.

At the same time, the agency also approved an inspection process to get those grounded jets back into the skies.

Boeing’s stock BA dropped 2.7% in premarket trading.

A Virgin Atlantic flight from Manchester to New York was cancelled after a passenger noticed several bolts were missing from the wing.

The transatlantic flight, VS127, was called off just moments before liftoff on 15 January even though the airline said there was no risk to passengers.

Phil Hardy, 41, a British passenger on the plane, alerted a flight attendant to the parts he noticed were missing, according to The New York Post.

Boeing shares fell in premarket trading in New York following the Federal Aviation Administration's announcement on Sunday recommending airlines to inspect another variant of the Boeing 737 for faulty mid-exit door plugs. This development occurred weeks after an incident where a door detached from an Alaska Airlines flight.

"As an added layer of safety, the Federal Aviation Administration (FAA) is recommending that operators of Boeing 737-900ER aircraft visually inspect mid-exit door plugs to ensure the door is properly secured," the FAA wrote in a statement. 

The Federal Aviation Administration is investigating whether Boeing failed to make sure a panel that blew off a jetliner in midflight last week was safe and manufactured to meet the design that regulators approved.

The FAA investigation announced Thursday is focusing on plugs used to fill spots for extra exits when those doors are not required on Boeing 737 Max 9 jetliners.

Boeing said it would cooperate with the investigation and one being conducted by the National Transportation Safety Board.

Shares of Boeing Co. dropped toward a six-week low Thursday, after the Federal Aviation Administration said it formally launched an investigation into whether the aerospace giant failed to complete safety tests on the certain products.

“This investigation is a result of an incident on a Boeing Model 737-9 Max where it lost a ‘plug’ type passenger door and additional discrepancies,” the FAA said in a statement. “Boeing’s manufacturing practices need to comply with the high safety standards they’re legally accountable to meet.”

The Federal Aviation Administration (FAA) said Thursday that it launched an investigation into Boeing to determine if the company failed to ensure that its products were safe for operation. 

"FAA formally notified Boeing that it is conducting an investigation to determine if Boeing failed to ensure completed products conformed to its approved design and were in a condition for safe operation in compliance with FAA regulations," the agency said in a statement. 

On Friday, January 5, the door plug of a commercial Boeing 737 Max 9 came off as the plane was climbing, opening a large hole on the side of the plane, alarming passengers onboard, and raising new questions about flight safety. For now, certain models of that plane have been temporarily grounded by the Federal Aviation Administration in the US and by several aviation authorities abroad, a move that impacts Alaska Airlines, United Airlines, and other companies that utilize this aircraft.

A 63 pound, 4-foot-long panel that blew off an Alaska Airlines plane in midair was found late Sunday in a backyard, giving investigators a key clue as they try to piece together why a gaping hole opened midair in the airplane’s side.