Boeing (BA  ) is in hot water once again with a group of the company's safety engineers coming forward to say their warnings were routinely ignored by management. In January, the company paid $2.5 billion to the Department of Justice to settle criminal probes into two 2018 and 2019 plane crashes that resulted in nearly 350 deaths.

The engineers bringing the allegations against Boeing are company employees who are deputized by the Federal Aviation Administration (FAA) to perform safety checks. In order to prevent unsafe planes from reaching the market, it's essential that these safety engineers are able to act without interference from the manufacturer.

However, according to an FAA letter to Boeing's leader of safety and aircraft certification, the engineers were routinely pressured by supervisors to give favorable reports. The letter describes engineers facing pushback from managers who complained that if the engineers found faults in the component designs, the production would be delayed.

"I had to have a sit down with a manager and explain why I can't approve something," one engineer is quoted in the letter. According to the engineer, Boeing found another engineer in the unit to perform the assessment.

"We take these matters with the utmost seriousness, and are continuously working to improve the processes we have in place to ensure the independence" of the FAA-deputized employees, Boeing spokesperson Jessica Kowal told reporters.

Kowal said that Boeing employees deputized to act on the FAA's behalf "must be accorded the same respect and deference" given to FAA personnel.

The FAA reportedly began its investigation into the matter in May and finished in July. The investigation involved surveying 32 of Boeing's roughly 1,400 FAA-deputized employees. A third of the respondents said that they were concerned about Boeing's treatment of safety concerns.

According to the FAA letter which was first reported on by the Wall Street Journal, the FAA plans to survey the remaining employees as a part of their broadening investigation into Boeing's safety culture.

"The environment does not support independence," FAA official Ian Won wrote in a letter to Boeing.

Ostensibly, FAA-deputized engineers are meant to use their specialized knowledge and skills to perform safety assessments and other safety-related work on behalf of the FAA without any interference. In practice, the FAA is often kept in the dark about safety concerns, including those raised by Boeing engineers regarding the infamous Boeing 737 Max.

This isn't the first time that Boeing employees have shed light on the company's inner workings. In January of last year, intra-company communication between Boeing engineers, supervisors, and other employees was released by the company. In those communications, employees write about their disdain for the plane manufacturer and the FAA, as well.

"This airplane is designed by clowns who are in turn supervised by monkeys," one employee wrote.

"I still haven't been forgiven by God for the cover up I did last year," another employee wrote regarding giving the FAA misleading information about the then-deadly 737 Max.

In October of 2019, messages from two years before the tragic 737 crash show technical pilots for the 737 discussing "some real fundamental issues" with the aircraft's systems which the pilot says Boeing officials "claim they are unaware of."