It is a pity that Diamond could not bring themselves to listen to TAE on the twinstar. TAE wanted them to have the little back up batterries which are fitted to the 172/PA28's as standard. These fag packet sized things will only power the fadecs for 20 mins. Diamond took the view that there was enough redundancy with having 2 engines! Aaaaaaargh! Never mind - you have to pay to learn.