My guess is they didn't sent it down 1000 times under robotic controland then tear it all down and look for damage, stress fractures, or to estimate lifetime.

My guess is they didn't sent it down 1000 times under robotic controland then tear it all down and look for damage, stress fractures, or to estimate lifetime. I mean why in the hell weren't there multiple and redundant, independently powered, sonar locators for example? You would be truly amazed how far sound can travel in water.