The Boeing 737 MAX and the 737 NextGeneration (NG) military derivative, the P-8 Poseidon, have been affected by another manufacturing quality issue. Spirit AeroSystems, a Tier 1 supplier for Boeing, confirmed that its 737 fuselages, which it ships to the planemaker from Wichita, Kansas, the United States (US), have been affected by a problem 5 days ago · What other problems have there been with the Boeing 737 MAX? Boeing has had to work to fix other manufacturing flaws with its 737 MAXs which have interrupted deliveries of the planes. The chief project engineer for Boeing’s 737 Max jet told House investigators that he approved a critical design change to software on the plane even though he was unaware of key details about lPqYn.