It has become very difficult to manage quality of products where suppliers provide materials and parts to specifications. Let's observe the problem with Ford Explorer and those darned tires. Some of the problem was lack of communication when Ford revised inflation standards for tires that had been designed to run stiffer. The manufacturer did not coordinate changes well enough with its supplier. Manufacturing problems were exposed, but not the manufacturer-supplier relationship.
There are lots of ways to fall astray. I once worked for a supplier of aerospace composites components. The specifications were exacting, but oversight was not always the best. Consequently there was a bit of wiggle room while making a product that appeared to conform to specs and did, as far as most could tell--even when processes were not controllable given the equipment being used. Until failure, however, things are good. Until a failure, what went on that didn't get found out? We will probably never know. If we knew, we'd perhaps be a mass of neurotics, afraid to go on a drive or flight!
This dangerous relationship is also evident in the airliners' outsourcing their maintenance. Remember the Alaska Airlines plane that went down from not enough grease on the tail flap screw? A subcontractor problem--out of date or insufficiently observed procedures lost scores of lives and Alaska's reputation tanked then.
It's easy to swing our gaze upon inspectors and suppliers, but the end client--in this discussion's case NASA, Ford, aircraft manufacturers and Alaska Airlines--is in charge of supplier control.
A material or procedural change is certainly not in the inspectors' purview. It is an engineering matter. It is also a management matter, since management deals with aspects non-technical, such as financing, scheduling and permission to wait while running all new tests on behavioral dynamics of this new material.
A person in the know once described to me the Challenger, um, accident in fair detail. As I remember the description the engineering staff, voiced by the head engineer, cautioned against the hydrogen fuel tank's o-ring leakage in chilly weather. Management, this person said, rescheduled after a number of postponements but in the end insisted the launch happen on that fateful day. The management reportedly demanded the head engineer watch and give his support, but he resisted and finally relented and did attend.
Of course the shuttle did launch. We now know the head of management was replaced, procedures and protocols went into overhaul and now they say the shuttle is nearly ready again.
And so the part I am not completely confident about is whether the new material dynamics have been sufficiently vetted. Nor have I read enough to become altogether satisfied that quality processes take programmic precedences--if the inspector is not procedurally able to complete the task, or if the criteria are not satisfactorily met, the thing should not launch and management has the responsibility to ensure that is so.
Discussions about vendor roles and inspection fulfillment do not address the question sufficiently for me; the foam insulation factor remains a planning and mechanical engineering matter. Inspection execution is influenced by process engineering. When I hear that management insists both material and procedural requirements be met before launch, like my command did for our submarines, I will feel so much better.