That doesn't absolve Boeing of responsibility here. Boeing develops and maintains the specifications for repair and maintenance work as well as criteria for re

That doesn't absolve Boeing of responsibility here. Boeing develops and maintains the specifications for repair and maintenance work as well as criteria for replacement parts. If United deviated from Boeing procedures or intervals when doing the work, or their supplier deviated in producing the product which caused the failure, that is not on Boeing. If the specifications (for repair work, or maintenance intervals, or replacement parts) were deficient, that falls on Boeing.