I42 - You and me both. In my uninformed way, I assumed someone in MoD said build a Rolls Canardly Mk II, Somewhere Dareospace built it, AAEE tested it to make sure it is up to spec and worked and was safely built. Ditto components like seats. Occasionally someone designed something, which someone else checks but although working with best endeavours cocks it up and the system is dangerous, eg fuel link up from probe in the Nimrod. Where does the "safety case" fit in, what does it do?