The FAA allows the certification of an aircraft, an aircraft system or an appliance used in the system by either testing it under operating conditions or by computer analysis. The problem identified comes under the heading of batch sensitivity where if one item in a series of items suffers from a quality or design problem it can be inferred that many if not all elements of that design have the same problem. The problem identified by the FAA indicates that the pumps were inadequately tested and that batch sensitivity seems to be present.
My question is why this problem was not identified in the Failure Mode Effects Criticality Analysis (FMECA) and a further expansion of this question is was an FMECA actually performed for the pump. If the original FMECA was properly performed the problem would have been identified and when Boeing fed that FMECA into their FMECA a safety hazard would have been identified and the pump design changed.
Many companies do not wish to identify potential problems and they hope that the airframe manufacturer will identify it. That way the Airframe Company will direct the supplier to make the necessary change and a scope change to the contract will be issued and the supplier will be paid for it.
Before I get sacked for the above I will state that this is my personal opinion.
