WATCH: New footage shows inspection inside Boeing plane after dramatic mid-air eruption
United Airlines announced that bolts requiring “additional tightening” were found during an inspection of a Boeing 737 Max 9.
United Airlines said “installation issues” with the door plugs would be “remediated” before the aircraft returns to service.
The inspection began after part of the aircraft fell from an Alaska Airlines 737 Max 9 on Friday.
Alaska Airlines later announced that it had discovered “some loose hardware” on some Max 9s.
The Federal Aviation Administration (FAA), which regulates air travel within the United States, grounded 171 of the aircraft.
“Since we began preliminary inspections on Saturday, we have found areas where we believe there may be problems with the installation of door plugs, such as areas where bolts may need to be tightened,” United said in a statement.
A door plug is a part of the fuselage with a window that fills the space where an emergency exit would be located in certain configurations.
It was this part of an Alaska Airlines plane that took a dramatic fall over the US state of Oregon and ended up landing in a teacher’s backyard.
The aircraft made an emergency landing, but there were no serious injuries to passengers or crew.
The National Transportation Safety Board announced Monday night that a plane door plug was recovered from an Oregon teacher’s backyard and four bolts were missing.
Commissioner Jennifer Homendy told reporters that the bolt may have been missing from the beginning, but could have come loose during the descent.
Most of the Boeing 737 Max 9s in use in the U.S. are operated by United Airlines and Alaska Airlines, but Turkish Airlines, Panama’s Copa Airlines and Aeromexico have also grounded the aircraft for inspection. .
Video: Teacher ‘quite surprised’ after finding airplane panel in garden
United Airlines said it had 200 canceled flights as of Monday and expected more cancellations on Tuesday.
“By switching to other aircraft types, we were able to operate some scheduled flights and avoided approximately 30 cancellations on Monday and Tuesday,” United added.
Alaska Airlines said initial reports from technicians preparing to inspect its 737 Max 9 aircraft indicated “loose hardware on some aircraft.”
“If we are able to move forward with the formal inspection process, all aircraft will be thoroughly inspected in accordance with the detailed instructions provided by the FAA in consultation with Boeing.”
“Any findings are fully addressed as an issue meeting our safety standards and FAA compliance. Formal inspections also require documentation of all findings, which are reported to the FAA. These steps The aircraft will not be returned to service until all are completed. ”
Earlier, the FAA announced it had provided a checklist for operators to follow during inspections.
The FAA announced that it is grounding all 737 Max 9 aircraft until operators “complete enhanced inspections of both left and right cabin door exit plugs, door components, and fasteners.”
“The operator must also complete any corrective action requirements based on the results of the inspection before returning the aircraft to service,” the statement added.
Flight 1282 had reached an altitude of 16,000 feet (4.8 kilometers) when it began its emergency descent Friday night, according to flight tracking data.
Images shared online and later by investigators showed a large hole in the side of the ship and oxygen masks hanging from the ceiling.
The Oregonian, citing passengers, said a boy sitting near the affected area had his shirt torn by the force of the decompression.
The U.S. National Transportation Safety Board (NTSB), which is leading the investigation into the incident, said pilots had reported that the pressurization warning light was on on three previous flights on the particular Alaska Airlines Max 9 plane involved in the incident. Announced.
NTSB Director Jennifer Homendy said the plane had been prevented from flying long distances over the water so it could “return to the airport very quickly” if the alert was raised again.
It is not clear whether the issues that caused these warnings are related to those that caused the Jan. 5 explosion.
“While awaiting Airworthiness Directive (AD) inspection standards from the FAA and Boeing, our maintenance team is ready to perform the required inspections on the 737-9’s intermediate exit door plug,” Alaska Airlines said in its latest statement. said. Max fleet.
“The grounding of the 737-9 Max has had a significant impact on our operations. 170 flights were canceled on Sunday and 60 flights were canceled on Monday, with more expected.”
“Safety is our top priority and we deeply regret the impact this incident has had on our customers and their passengers,” Boeing said in a statement.
The company’s 737 Max has been described as “the most scrutinized transport aircraft in history” after a series of safety issues.
In late 2018 and early 2019, two aircraft were lost in nearly identical accidents off the coast of Indonesia and on the outskirts of Ethiopia’s capital Addis Ababa.
A total of 346 people died. Both crashes were caused by flaws in the flight control software, which ultimately forced the planes into catastrophic dives despite the pilots’ best efforts.
