Boeing employees knew about problems with flight simulators for the now-grounded 737 Max and apparently tried to hide them from federal regulators, according to documents released Thursday.
Boeing said the statements "raise questions about Boeing's interactions with the FAA" in getting the simulators qualified. But said the company is confident that the machines work properly.
"These communications do not reflect the company we are and need to be, and they are completely unacceptable," Boeing said in a statement.
Employees also spoke about Boeing's senior management, the company's selection of low-cost suppliers, wasting money, and the Max.
"This airplane is designed by clowns who in turn are supervised by monkeys," one employee wrote.
Names of the employees who wrote the emails and text messages were redacted.
The Max has been grounded worldwide since March, after two crashes that killed 346 people. Boeing is still working to update software and other systems on the plane to convince regulators to let it fly again. The work has taken much longer than Boeing expected.
The latest batch of internal Boeing documents were provided to the Federal Aviation Administration and Congress last month and released on Thursday. The company said it was considering disciplinary action against some employees.
An FAA spokesman said the agency found no new safety risks that have not already been identified as part of the FAA's review of changes that Boeing is making to the plane. The spokesman, Lynn Lunsford, said the simulator mentioned in the documents has been checked three times in the last six months.
"Any potential safety deficiencies identified in the documents have been addressed," he said in a statement.
A lawmaker leading one of the US congressional investigations into Boeing called them "incredibly damning."
"They paint a deeply disturbing picture of the lengths Boeing was apparently willing to go to in order to evade scrutiny from regulators, flight crews, and the flying public, even as its own employees were sounding alarms internally," said Rep. Peter DeFazio, D-Ore., chairman of the House Transportation Committee.
DeFazio said the documents detail "some of the earliest and most fundamental errors in the decisions that went into the fatally flawed aircraft." DeFazio and other critics have accused the company of putting profit over safety.
The grounding of the Max will cost the company billions in compensation to families of passengers killed in the crashes and airlines that canceled thousands of flights. Last month, the company ousted its CEO and decided to temporarily halt production of the plane in mid-January, a decision that is rippling out through its supplier network.