Boeing Co.’s quality management system came under close scrutiny at a hearing investigating the January 5 accident on a 737 Max 9 aircraft, with one worker representative criticizing the processes as overly complex and difficult to follow. 

The company’s system “is very complicated,” said Lloyd Catlin, a business representative for the International Association of Machinists and Aerospace Workers, which represents thousands of Boeing employees. The procedures and instructions have “been through so many changes, especially over the last 10 years, that it’s very ambiguous and open to misinterpretation,” he said. 

The complaints were raised during the second day of an extensive hearing held by the U.S. National Transportation Safety Board to get to the bottom of why a panel blew off a nearly-new Boeing 737 Max 9 aircraft in January. Since the accident, Boeing has said it’s made strides to address quality lapses at its factories, including by simplifying instructions for workers. 

The hearing covers a range of topics, including the manufacturing of the 737 Max, the events leading up to the panel — known as a door plug — falling off mid-flight, Boeing’s safety and quality management systems, and the Federal Aviation Administration’s (FAA) oversight of the planemaker. 

Boeing’s factory processes have been under the microscope of regulators and safety inspectors since the accident. The FAA put out a scathing report earlier this year that faulted Boeing for unclear processes, in which workers aren’t aways aware of the demands of senior managers. 

One possible source of confusion, according to Catlin, comes from the fact that Boeing has changed the terms in procedures and instructions over the years. For example, inspections were changed to verifications and more recently to conformance decisions. Those types of tweaks can appear minor on the surface but have a big impact on who actually performs the work, he said. 

“They appear to be slight changes, but they are dramatic changes,” Catlin said in response to questions at the hearing.

Hector Silva, vice president of regulatory compliance and core quality for Boeing’s commercial airplanes division, said at the hearing that he understands Catlin’s concerns and that the company is trying to communicate better upfront about the reasoning behind certain changes. He also said Boeing is trying to get more feedback on internal processes and procedures from the individuals on the shop floor who interact with them every day.