Renton, Washington
CNN
—
The investigation into the January blown door plug on an Alaska Airlines 737 Max jet was hampered for months by missing documents, making it difficult to pinpoint who made the mistake that nearly led to the tragedy. Boeing said this week that the paperwork may have caused the problem in the first place.
It is already well known that a door plug came loose after the plane reached an altitude of about 16,000 feet, causing uncontrolled decompression, injuring several passengers and causing ripped shirts, but no documentation has ever been found to show who worked on the door plug.
But at a news conference at Boeing's 737 Max factory in Renton, Washington, Boeing said a documentation deficiency was the reason four bolts needed to secure the door plugs weren't installed before the plane left the factory in October. Workers who had to reinstall the bolts didn't receive work instructions telling them what they needed to do.
Without the bolt, the door plug accident would have been almost inevitable – fortunately, it was not fatal.
It's a symptom of workmanship problems on Boeing's assembly lines that have been the focus of multiple federal investigations and whistle-blower complaints and have caused delays in jet deliveries that are causing headaches for airlines and passengers around the world.
But leaking details at this stage could land Boeing in further trouble with regulators. The National Transportation Safety Board (NTSB) reprimanded the company on Thursday for leaking “non-public investigative information” to the media. In a statement, the board said the company “clearly violated” its rules.
“At Tuesday's quality improvement press conference, Boeing executives provided investigative information and analysis of previously released factual information. Both of these actions are prohibited,” the NTSB said.
The NTSB said Boeing will no longer have access to information the NTSB develops during its investigation, adding that it would report Boeing's conduct to the Department of Justice.
“Having been involved in many NTSB investigations over the past few decades, few organizations know the regulations better than Boeing,” the NTSB said.
NTSB Aviation Safety Director Timothy LeBaron said in a letter sent Thursday to Boeing CEO Dave Calhoun that this week's media briefing was conducted without the regulator's consent or knowledge.
“Boeing must take all reasonable steps to prevent investigative information from being made public,” he wrote. “Such disclosure and concealment of critical information from investigators is a clear violation of NTSB rules.”
Boeing responded by saying it held the meeting to “take responsibility” and be transparent about its role in the accident. The company said it “shared information about lessons learned from the January 5 accident.”
“We deeply regret that some of the comments we made to clarify our responsibility for the accident and explain the actions we are taking went beyond the NTSB's role as an investigative source,” Boeing said in a statement. “We apologize to the NTSB and stand ready to answer any questions as the agency continues its investigation.”
The NTSB also sharply criticized Boeing earlier this month for saying that a rare and dangerous forward/backward roll of a Southwest Airlines 737 Max aircraft during a flight in May was not the result of a design or manufacturing flaw. The NTSB, which is investigating the accident, told Calhoun on Thursday that it had not yet made a decision and that Boeing and the NTSB needed to come to a public understanding.
Boeing said in a briefing on Tuesday that the reason the Alaska Airlines door plugs weren't secured in place in the first place was because two separate groups of factory workers were responsible for the job, with one group removing the door plugs and the other reinstalling them while the plane was moving through the assembly line.
The first group of employees removed door plugs to address issues with rivets made by supplier Spirit AeroSystems, but did not provide documentation showing that they removed the door plugs and the four bolts needed to secure them in place to perform that work.
When a different group of workers put the plug back in place, Boeing said the employees did not believe the plane could actually fly in that condition.
Instead, they sealed the hole with a plug to protect the interior of the plane from the weather while it was moved to another location on the factory grounds. Employees in the group make such temporary repairs frequently.
“The door team closes the doors before the aircraft leaves the aircraft, but it is not their responsibility to install the pins,” said Elizabeth Lund, senior vice president of quality for Boeing Commercial Airplanes.
Presumably, these employees assumed that documentation existed showing that the plugs and bolts had been removed and that someone else would install the bolts based on that documentation.
But without the paperwork, no one on the assembly line knew the door plugs had been removed or that the bolts were missing, Mr. Land said. Door plugs are rarely removed after planes arrive from Spirit AeroSystems, so no one realized the door plugs needed attention, he added.
“The (permanent) reinstallation will be done by a different team based on documentation that shows what work remains to be done,” Rand said, “but because there was no documentation, no one knew to follow up.”
Despite the missing bolts, the plane continued flying for about two months with the door plug still attached. But on January 5, minutes after an Alaska Airlines flight took off from Portland, Oregon, the door plug blew off, blowing a large hole in the side of the plane. Passengers' clothes and cell phones were ripped off and sent flying into the night sky. Fortunately, no passengers were seriously injured, and the crew was able to land the plane safely.
The missing bolt was identified in a preliminary investigation by the National Transportation Safety Board, but its report did not lay any blame for the accident. A final report is not expected for more than a year. An NTSB spokesman said the safety agency is continuing its investigation and would not comment on Boeing's explanation for the mistake.
The committee released its interim report in February, finding that the bolts were missing when the planes left the Boeing factory but not assessing responsibility. A final report is not expected for more than a year.
NTSB Chair Jennifer Homendy has testified about the missing documents at congressional hearings since the preliminary report was released.
Boeing is dealing with the problem by slowing down the assembly line and making sure planes don't go ahead with the problem, on the assumption that the issues will be addressed later in the assembly process, Lund said.
“We have slowed down operations at our factories to ensure we get the situation under control,” she said.
“We are very confident that the steps we have taken will ensure the safety of every aircraft leaving this factory,” she added.
View this interactive content on CNN.com
