The US Federal Aviation Administration has indefinitely extended the grounded status of Boeing 737-9 Max aircraft given the more stringent requirements it put forward after an Alaska Airlines flight suffered a window blowout shortly after take-off last week.
The regulator has required the US plane maker, one of the world's biggest, to provide additional data before the agency approves an “extensive and rigorous inspection and maintenance process for returning 737-9 Max aircraft to service”, it said on Friday.
In addition, the FAA has required 40 aircraft to undergo inspections of their door plugs – a panel fitted in place of an unused emergency exit that may have caused the Alaska accident.
The FAA said that while it is “encouraged” by the “exhaustive nature” of Boeing’s instructions for inspections and maintenance, the agency will not approve the inspection and maintenance process until it reviews data from the initial round of 40 inspections, “in the interest of maintaining the highest standard of safety the agency”.
“We are working to make sure nothing like this happens again. Our only concern is the safety of American travellers and the Boeing 737-9 Max will not return to the skies until we are entirely satisfied it is safe,” FAA administrator Mike Whitaker said.
The Alaska blowout incident happened on January 5, which left a gaping hole in the side of the aircraft's fuselage.
There were 177 people on board the Alaska Airlines plane, which made an emergency landing when a window panel blew out after take-off. The plane had departed from Portland International Airport in Oregon. The cabin crew reported a pressurisation issue and the flight returned to the ground after 20 minutes.
The incident also happened a week after Boeing urged airlines to inspect 737 Max aircraft for a possible loose bolt in the rudder control system, according to the FAA.
Fellow US carrier United Airlines on Monday said it found loose bolts in Boeing 737 Max jets as it carried out inspections after the Alaska episode.
“Since we began preliminary inspections on [January 6], we have found instances that appear to relate to installation issues in the door plug – for example, bolts that needed additional tightening,” United, one of the world's biggest airlines, said.
Both Alaska and United have suspended Boeing 737-9 Max flights until Tuesday.
On Thursday, the FAA announced an investigation to determine if Boeing failed to ensure completed products conformed to its approved design and were in a condition deemed safe for operation in compliance with the watchdog's regulations.
On Friday, the agency said it will increase its supervision of Boeing's production line as it reassesses safety risks following the Alaska incident.
Boeing stocks also took a hit when markets opened this week, closing down more than 8 per cent at the end of the trading on Monday.
On Tuesday, Boeing chief executive Dave Calhoun said that the plane maker should accept the fault and make amends after the blowout led to concerns about its quality standards.
“Upon a full review of the data the FAA will make a determination whether the instructions satisfy compliance with the highest standard of safety,” the FAA said.
“If the FAA approves Boeing’s inspection and maintenance instructions, operators will be required to perform that regimen on every aircraft before it is returned to service.”
