Relating to the Gazelle, it was to be used for high alt but by default, we turn it on for start and leave it on (unless it looks like its going to be a hot T4) in all regimes. Engine starts quite happily with it deselected. The boost pump opens the micro pump which bypasses the main FCU to 'prime' the system. Not really required seeings how youre going to squirt a shed load of juice in when selecting 'Run'.