This part of the Alaska Airlines plane detached mid-flight over the US state of Oregon, landing in a teacher’s backyard.
An emergency landing was executed, with no serious injuries to passengers or crew.
The National Transportation Safety Board revealed that the plane’s door plug was found without the four bolts.
The majority of Boeing 737 Max 9s in the US are operated by United Airlines and Alaska, with Turkish Airlines, Panama’s Copa Airlines, and Aeromexico also grounding the same model for inspections.
United mentioned cancelling 200 flights as of Monday, with expectations of significant cancellations on Tuesday.
Alaska Airlines reported initial findings of “some loose hardware” on their Max 9 fleet, emphasizing thorough inspections following formal procedures provided by the FAA and Boeing.
The FAA issued a checklist for operators to follow during inspections, keeping all 737 Max 9 aircraft grounded until enhanced inspections and corrective actions are completed.
Flight 1282, involved in the incident, descended from 16,000ft (4.8km) on Friday evening, revealing a hole in the craft’s side and deploying oxygen masks.
The US National Transportation Safety Board reported pressurization warning lights on three previous flights of the specific Alaska Airlines Max 9 involved.
The NTSB chief mentioned restrictions on long-haul flights over water due to these warnings, though the connection to the recent blowout is unclear.
Alaska Airlines said its 737-9 Max fleet’s grounding has significantly impacted operations, with numerous flight cancellations.
Boeing expressed regret for the impact on customers and passengers, emphasizing safety as a top priority.
The 737 Max faced heightened scrutiny after two crashes in 2018 and 2019 caused by flawed flight control software, resulting in 346 fatalities.