A three-year-old internal Boeing survey found that one in three employees felt “potential undue pressure” to approve their own aircraft safety features, The Wall Street Journal reported Sunday.

The 2016 survey found that some 29% engineers felt pressure from their managers to certify for the Federal Aviation Administration plane systems that they had designed themselves, reported the Journal’s Andrew Tangel and Andy Pasztor, who reviewed the survey.

The survey also highlighted the dangers of having Boeing employees develop as well as certify their own work, noting that “conflict can occur” in times like this, the Journal added.

Workload and schedule were cited as major causes for the stress. More than 80% of respondents did add, however, that they were confident that they could address concerns about undue pressure, according to the Journal.

Boeing 737 Max

Foto: Undelivered Boeing 737 Max planes parked idly in Seattle, Washington, in August 2019.sourceDavid Ryder/Getty Images

The House Committee on Transportation and Infrastructure is currently scrutinizing this survey as part of its investigation into the design and development of the Boeing 737 Max, which includes scrutiny into how the plane got FAA approval.

The House probe came after two deadly crashes that killed a total of 346 people within five months of each other.

The Committee on Transportation and Infrastructure and Boeing have not yet responded to Business Insider's requests for comment on the survey and Boeing's work culture.

An FAA spokesman declined to comment on the survey, saying in a statement to Business Insider that the administration has not seen the document.

"The FAA takes allegations of undue pressure seriously, and investigates all reports of such activity that are made to FAA inspectors or through the agency's safety hotlines," the spokesman added.

boeing 737 max ethiopian airlines

Foto: An Ethiopian police officer walks past debris of the Ethiopian Airlines Flight ET 302 plane crash in March 2019.sourceREUTERS/Baz Ratner

Boeing has faced increased pressure in recent days, after leaked messages between its top chief technical pilot and his colleague in 2016 - around the same time employees were answering the survey - suggested that the company misled the FAA about the 737 Max's safety issues.

Read more: Messages reveal a top Boeing pilot knew about problems with the 737 Max's 'egregious' behavior before 2 deadly crashes

A panel of air-safety regulators earlier this month slammed the FAA's "inadequate awareness" of Boeing's anti-stall software, which has been blamed for the two crashes.

All Boeing 737 Max planes around the world remain grounded, with airlines scrambling to work out how to tell passengers they're flying on a 737 Max when they return to service.

The Committee on Transportation and Infrastructure is scheduled to hold a hearing on the "design, development, and marketing" of the Boeing 737 Max on October 30.

Read the full story on the survey from the Wall Street Journal »