It was an engineer, Roger Boisjoly, who repeatedly warned about the safety of the o-rings, particularly in low temperatures. The decision to launch the shuttle came from management not the engineers.
Feynman was on the accident investigation committee, and was critical to exposing crucial facts and making sure they made it into the report. Feynman even wrote an additional report to add to the committee's work. http://www.ralentz.com/old/space/feynman-report.html
Bolsjoy's ordeal is now in the curriculum of many engineering ethics courses.
Thus decisively proving the parent's point. Boeing might have the most talented engineers in the world, but if management ignores them then all their degrees and seriousness doesn't mean jack.
http://www.space.com/14522-roger-boisjoly-shuttle-challenger...