In June 2015, SpaceX's mission CRS-7 on Falcon 9 was lost when the rocket exploded on takeoff. SpaceX investigation concluded that the problem was a failure of a single defective strut. The strut's design load was 2,000 lb and it was rated for 10,000 lb, 5 times higher.
It sounds like a good news for SpaceX — just improve quality control to catch bad parts and you're done. But is it so easy? I wonder if there is a fundamental design flaw there. Why did a failure of a single strut bring down the whole system? Is every strut in Falcon a Single Point of Failure (SPOF) then? Or even just some of them? That would still be a dangerous design.
For space missions, redundancy is expected and engineers take precautions against failing parts, elements and subsystems. Every SPOF is an invitation of trouble. So assuming what SpaceX says is true, is it a sign of bad high-level structural design or what?