US airline United Airlines discovered unopsported gates on the Boeing 737 Max 9 aircraft that the airline had suspended after the clearance of the airspace on a Alaska Airlines flight.
The rival airline's discovery raises new safety concerns for the Boeing 737 Max 9, which was previously suspended after two fatal plane crashes.
United Airlines said in a statement: Since we began a preliminary inspection on January 6, we have detected cases related to installation problems at the door, such as bolts that need to be tightened. These findings will be addressed by our technical team to safely return the plane to operation.
The US Federal Aviation Administration (FAA) has suspended all 737 Max 9 flights for safety inspection after the fence was torn in the air during a Alaska Airlines flight on January 5.
The crew was forced to return and make an emergency landing at Portland Airport, Oregon, where the flight departed, and some of the 171 passengers were injured.
The FAA's decision affected about 171 aircraft and caused hundreds of flights to be canceled. United Airlines has 79 Boeing 737 Max 9s in its fleet. The airline did not disclose how many of the plane had loose feathers. Alaska Airlines has 65 Max 9.
The FAA said all Max 9 aircraft will remain suspended until operators complete advanced inspections and take all necessary remedial actions. The FAAs priority is to always keep Americans safe, the FAA stressed.
A separate agency, the National Traffic Safety Committee (NTSB), is investigating the case of the plane's door opening. The locked door was opened at an altitude of about 4,800 m and was found by a teacher in Portland in the yard behind his house.
The unlocked plane was previously suspended by Alaska Airlines for flights to Hawaii because the pressure warning lights were lit on some previous flights - NTSB President Jennifer Homendy informed the press on January 7.
Homendy said the plane was restricted to making shorter flights over land to be able to come back to the airport very quickly if the warning lights re- lit. However, the NTSB has not yet confirmed a link between previous pressure warnings and the January 5 opening.
Aviation regulators around the world banned 737 Max - Boeing's best-selling passenger carrier - in March 2019, after accidents in Indonesia and Ethiopia killed a total of 346 people.
Aircraft were allowed to fly again in the US and most other major markets about two years later, after repairing flight control systems - which were believed to have caused accidents.
New safety concerns emerged last month, when Boeing called on 737 Max operators to check the plane for loose locks in the steering wheel control system. The warning was issued after an unidentified airline found a wheelchair bridge lacking a snail belt during regular maintenance.
