A bit off thread for which I apologise;when I was an engineer with Flybe/MAEL, I went for engine ground running and taxiing continuation training on the Q400 in the sim. All's went ok, but the instructor said that there was no need to pull the fire handles. I countered that surely the aircrew did that at least on the first flight to ensure that the fuel/hyd shut-off valves operated, and that the crew didn't want to find out that one of the valves was U/S when he really needed it?! The instructor said that he would look into it, but I never heard any more. However, I continued to check the valve operation.