Delays in the supply of parts are causing a slowdown in production of the 737 MAX in Renton, impeding Boeing’s push toward a target rate of building 31 of the jets per month.

To try to stabilize production, Boeing is handling the issue differently than in the past. Instead of rolling unfinished planes through the assembly line and out onto the field where the missing parts can be installed later, it’s pausing the jets on the moving line.

A person familiar with the current production status said Friday that for a period of roughly 10 days last month, airplanes were held in position on the moving line awaiting delivery of parts missing because of supply chain issues.

The person said production work did not stop, but continued in various sections of the airplanes during these pauses on the moving line.

In a statement Friday, Boeing said “production activities in Renton have continued and are ongoing.”

“As we have said, we are driving stability in our factory and would rather perform work in their designated position rather than pass that work onto the next position,” Boeing added.

In the past, Boeing has typically not let delays in delivery of even major parts hold back the pace of its moving lines. Instead, it installed those parts after the rest of the plane was complete and had rolled out of the factory.

This is known as “traveled work,” since the work travels from the factory out to the field. However, too much traveled work creates chaos because installation of the parts must be completed out of the normal sequence, resulting in some disassembly and rework.

In the summer and fall of 2018, a pile up of traveled work due to late delivery of engines and fuselages resulted in dozens of airplanes being worked on in the field. As overworked employees tried to maintain the delivery schedule, quality issues proliferated.

Ed Pierson, a production manager there at that time, became so concerned at the danger posed that he sent an email to the executive in charge of Renton stating that for the first time in his life he was “hesitant about putting my family on a Boeing airplane.”

Pierson was ignored then. Now, Boeing may have taken heed and wants to avoid similar chaos this time.

The 10-day pause in the moving line in May was first reported Friday by The Wall Street Journal.

Speaking at a Goldman Sachs conference on May 11, Boeing Chief Financial Officer Brian West, noted then that “one particular wiring connector … has us slowing things down.”

“It’s a reflection of a crazy supply chain world that we live in right now. But I will tell you that we slowed it down deliberately,” West said. “We can’t go back to a world where we are traveling lots of work. We have to stay disciplined, and we have to drive stability.”

To achieve stability, he said Boeing is “willing to slow things down, or in some cases, just pause if all the parts aren’t there.”

Complicating matters, Boeing still has 240 of 450 MAXs that were built and then grounded following a second crash, in Ethiopia in March 2019, parked around the region that haven’t yet been reworked and delivered.

Speaking early Friday at a Bernstein Conference, Boeing CEO Dave Calhoun said Boeing is still working toward a stable target rate of 31 jets per month.

He added that the MAX “is still the most labor and human resource consuming recovery that we have.”

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