"Something happened in the translation from, 'let's build a high-quality, safe product' to 'let's get it out done on time,'" former Boeing senior manager Ed Pierson told the ABC.
"A lot has been said about the pressure on engineers to get the plane designed and test pilots to get the plane tested," Mr Pierson said.
But Mr Pierson remains concerned production problems at the plant in the lead up to the tragedies may also have inadvertently embedded safety defects in subsequent planes.
Boeing said it took Mr Pierson's concerns "seriously" and took "appropriate steps to assess them", adding none of the authorities investigating the fatal crashes found production conditions had contributed to the accidents.
The FAA told the ABC that the 737 MAX series planes would remain grounded as long as needed, but Boeing has already told shareholders it is pinning hopes on a mid-year return to the sky.