Jennifer Homendy, chairwoman of the National Transportation Safety Board, spoke late Monday about the ruptured fuselage of Alaska Airlines Flight 1282, citing the likelihood of negligence on the part of the airline.
Instead, the NTSB's initial findings focused solely on the fabrication and installation of the door plug that fell off the 737 MAX 9 aircraft, leaving a gaping hole in the passenger cabin wall and causing the plane to rapidly depressurize at 16,000 feet
That leaves supplier Spirit AeroSystems of Wichita, Kansas, responsible for installing the door stopper and Boeing in Renton for final inspection of the component before it is sealed behind the insulation and sidewall.
Hopes that this incident might be a one-time anomaly were dashed Monday when both Alaska and United found loose screws on the door plugs while inspecting other MAX 9s. This now looks more like a serious factory quality control issue for Boeing.
The plug is a plate used to seal a fuselage cutout for an optional emergency exit door used by only a few high density airlines. Most airlines, including Alaska and United in the US, do not have a door there, but instead install the plug, which appears like another window to passengers inside.
The focus of discussion at Monday's news conference, after investigators examined both the plane and the fallen door stopper – it was found in a Portland teacher's backyard on Sunday – was four missing bolts that would have held the door stopper in place should .
“We don't know if there were bolts there or if they were simply missing and came loose when the door plug came loose … during the violent explosive decompression,” Homendy said.
More about Alaska Airlines and the Boeing 737 MAX 9
On Tuesday, a statement from the Federal Aviation Administration suggested that the MAX 9's return to the skies could take a while.
The FAA confirmed that Boeing sent initial inspection instructions to airlines on Monday that were inadequate. Boeing must revise these instructions and receive approval from the FAA.
“The safety of the flying public, not speed, will determine the timeline for returning the Boeing 737-9 Max to service,” the FAA said.
Alaska Airlines said Tuesday that it is still awaiting approved final inspection and maintenance instructions for its fleet of 65 MAX 9s.
“Until then, the Boeing 737-9 MAX fleet remains grounded,” Alaska said.
A gloomy Boeing gathering
As Boeing tried to take stock of the impact of the accident on Tuesday, top executives gathered in Renton for a safety meeting for employees.
CEO Dave Calhoun, new chief operating officer Stephanie Pope, chief safety officer Mike Delaney and Commercial Airplane Division CEO Stan Deal all spoke at midday to about 500 employees at the factory where the MAX is assembled. The meeting was webcast to all Boeing employees.
A five-minute video posted by Calhoun at the meeting, showing Calhoun's somber remarks, shows him pause briefly and nearly choke as he talks about seeing photos of the hole in the plane's fuselage with passengers nearby.
“I have children, I have grandchildren and so do you,” Calhoun told employees. “This stuff is important. Every detail counts.”
Friday's collapse “shocked me to the bone,” he said.
He called the accident “a reminder of the seriousness with which we must approach our work” and said it created “a very troubling moment” for Boeing's airline customers.
He said Boeing would seek to restore airlines' trust by “being willing to work with them directly and transparently to ensure that they understand that every plane that has Boeing's name on it and that is in the sky is, in fact, safe.” is.”
First NTSB results
At the NTSB press conference Monday evening, Homendy provided more details about how frightening the incident was for the passengers of Flight 1282.
She said emotional interviews with the flight attendants showed they were dealing with “a lot of trauma.”
The flight attendants told investigators that they were unable to communicate with each other and understand what was happening because of the noise. Those in the back of the plane closest to the hole that opened couldn't even see it from their position.
“It was pretty frightening,” Homendy said for the cabin crew, appealing to the media to give them space and time to recover.
The NTSB's initial conclusion after inspecting the aircraft and the 63-pound door plug is that four screws that should have prevented the plug from moving out must have been either missing, misinstalled or broken.
On the aircraft, six small brackets on either side of the door frame – twelve in total, called “stop fittings” – are aligned with twelve similar stop pads on the door stop.
When the passenger cabin is pressurized, the stop pads press firmly against the stop fittings and seal the door plug tightly to the fuselage.
To service the door stopper, it is opened by moving the stopper upwards so that the pads on the door stopper extend over the stop fittings on the door frame, allowing the stopper to move outward.
There are pins that look like screws in the photos that go through the center of the stop fittings. However, these only serve to align the door stopper. They are not structurally strong.
What keeps the door stopper from flying out in the air are four bolts, two at the top and two at the bottom, secured with locking wires that prevent it from moving up.
The top bolts pass through guide rails on either side of the door plug to prevent the roller pins on the fuselage frame from slipping out of the guides.
The lower bolts pass through two shafts at the bottom of the door, which prevent the underlying springs from pushing the door stopper up.
When these screws are in place, the plug cannot move up and the 12 stop pieces press against the stop pads to hold it in place.
“Today's investigation showed that the door did indeed move upward,” said NTSB structural specialist Clint Crookshanks. “All 12 stops were released, allowing it to fly out of the fuselage.”
Both roller tracks were found to be broken at the door stopper. The screws were not found.
“We have not yet recovered the four bolts that prevent the door stopper from moving vertically,” Crookshanks said. “And we haven’t determined if they existed there yet.”
Homendy added that a microscopic examination of the door plug at the NTSB laboratory in Washington, D.C. will determine whether the bolts are in place or not based on the scratch marks.
Overturning Alaska's decision to fly the plane
While these questions arise, Homendy explained why she is much less concerned about multiple pressure loss incidents before Friday's accident.
Flights of this new MAX 9 had experienced intermittent warning lights indicating a brief reduction in cabin pressure on December 7 and again on January 3 and 4, the two days before the incident.
Therefore, Alaska decided not to fly the jet over water on long-haul flights. So it could fly from Portland to California, but not to Hawaii.
Many were shocked to read about this decision in press reports and expressed their outrage on social media.
But Homendy said she believes those three incidents likely had nothing to do with the broken door stopper and that Alaska's decision made sense.
She explained that the pressurization of the MAX cabins is a triple-redundant system with primary and secondary computer controls supported by a manual option for the pilots.
In the three previous incidents in which the warning lights came on, the primary control had failed, but the secondary system kicked in with no significant impact.
Investigators will continue to examine pressure logs, Homendy said, but “at this point we have no indication that this is in any way related to the door plug ejection and rapid decompression.”
And she said Alaska's decision to restrict the jet from long-haul flights over water was not required by law but was a precautionary measure the airline took voluntarily to provide an additional margin of safety when key systems showed signs of a recurring problem.
The logic is that if a plane gets into trouble while flying from Portland to California, it can easily find a place to land. If something goes wrong in the middle of the ocean, it's much more dangerous.
The MAX is certified for routes more than three hours from the nearest airport.
Homendy said the policy to prevent this at any sign of a system problem is “an additional step that Alaska Airlines has taken.”