Chairman et al,
Some thorough scrutiny of the FAA "rules" when you are the STC holder or the PMA holder may well prove worthwhile.
I refer, of course, to the FAA process for both of the above finding compliance for materials used in manufacture.
For example, there is no PMA (or otherwise approved) manufacturer of the large diameter aluminium irrigation pipe that forms a substantial part of the fuselage of several LSA, but the same general principle applies to any Part 23 aircraft. It is, in this case and similar, the STC/PMA holder that finds compliance as per their specifications that form a major part of the STC/PMA documentation.
Tootle pip!!
PS: There is one helicopter manufacturer uses off spec (out of tolerance) new production bearing in a rotor head, the normal industrial spec. is "too tight", so they use bearing that have failed QC because the races have "excess" clearance. OK in you rotor head but already worn out, if it is the front wheel bearings of your auto. The bearing OEM is more than happy to sell a few sets, rather than having to bin them.