although the ntsb and pcu manufacturer parker hannifin had already determined Deciding that the pcu was properly working Employment , and thus not the cause of the crash , a private investigation into the crash for a civil lawsuit Legality tried by jury in a state court in los angeles , which was not allowed Preventing_or_letting to hear or consider the ntsb 's and parker hannifin 's conclusions Statement , decided Deciding that the crash was caused Causation by a defective servo valve inside the pcu , based on forensic findings from an electron microscope which determined Deciding that minute defects within the pcu had caused Causation the rudder unk and a subsequent uncontrollable flight and crash Catastrophe .