A small group of Boeing engineers who perform key safety tasks are raising concerns about their ability to work free of pressure from supervisors, and their comments are prompting federal regulators to take a broader look into the company’s safety culture. The employees are deputized to approve safety assessments and handle other jobs for the Federal Aviation Administration, making their independence from company pressure critical. According to an FAA letter, one of the employees said, “I had to have a sit down with a manager and explain why I can’t approve something.” The worker indicated that the company shopped around for another employee in the engineering unit. Another employee reported consternation by managers when engineers find fault in the designs of components because that can cause delays in delivering airplanes. The FAA’s initial investigation ran from May until July. An FAA official described it in an Aug. 19 letter to …