I've noticed that during any flight, despite having the fuel selector centred on Norm, the fuel in the aft tank only is used which ultimately results in port engine fuel starvation and stoppage.
I must admit that I am not totally familiar with the Twin Otter fuel system but am puzzled that I have not seen comments from anyone else about this. All flights I have done so far have been after selecting "FLY" and commencing with engines started on the runway.
What is it that I am not setting