I've been reading a few of the articles with "the 737 was returned to service too soon" angles to keep apprised of any further concerns, or at least public sentiments. I was surprised to see one this week from the BBC citing Ed Pierson, a former 737 production manager, once again:https://www.bbc.com/news/business-55751150
I assume he will continue to press this case, so it seemed worthwhile to read his latest report and discuss it.
From a position of having observed concerns on the production line under rate pressure, he is arguing there are still unresolved issues. I would say one of his biggest concerns was out-of-sequence work and rework to address QA findings. Many of us remember the accumulation at the time of 737's being parked at Boeing Field to complete these tasks before delivery, as well as delays receiving engines. I seem to recall at one point, for example, Boeing was making ferry flights to free up space in Renton, then removing the engines to truck back to Renton for another aircraft.
He seems to mainly focus on why the AoA sensors failed - the bird strike on the Ethiopian flight has not been concretely proven. The miscalibrated AoA sensor was installed on the Lionair flight due to issues with the factory-installed sensor. He cites interesting results from inspections of the removed sensor that was found to have had a portion wire inadvertently epoxied against materials with differing coefficients of thermal expansion, leading to thermal cycling failure.
I actually find the details he highlighted from the investigations and from his own experience in the factory quite interesting. I agree with him that if Collins Aerospace has quality control problems with their AoA sensors, those should be addressed. And it was clear even before the crashes that Boeing needed to resolve the difficulties in their production system - indeed, that was one of the reasons Boeing cited for slowing and then shutting down production after the grounding even though they believed deliveries would resume soon.
However, from there goes makes his own conclusions in contradiction with the exhaustive investigations and recertification efforts:
The design of the 737 MAX, MCAS software and the failure to provide vital information and training to pilots did not trigger these accidents.
Overall, I think the most significant issue with his arguments for denying the MAX approval to return to service is an assumption on his part that a failed AoA sensor is still a major hazard. It is quite clear that all of the regulatory bodies recognize that AoA sensors are an exposed part that has to be assumed at risk of failure, so a thorough safety assessment had to be done for that scenario, and the resulting effects mitigated to a low level of remaining risk.
I hope his comments helps ensure those remaining factors get addressed in the near term, or even better, that they are being addressed independent of his efforts, but since the recertification requirements addressed the effects of his concerns, I disagree with his conclusion that the grounding was lifted too soon.