Tom
Put simply, second segment climb finishes at 1500' agl with the required gradient being predicated on the worst case scenario, an engine failure at V1. If an engine fails after V1 but before VFTO then, if you pitch to V2, you will achieve a known gradient starting from a higher point, which is a bonus. If you have already accelerated to VFTO (around 160kts in the Hawker) and have retracted flaps before an engine fails then the Hawker AFM advises to continue climb at that speed until clear of obstacles. In other words, for the Hawker, second segment climb gradient is assured below 1500' as long as the flaps are retracted at or above VFTO and that speed is maintained until 1500'. However, there is no harm in leaving flaps at 15 with all engines running until 1500' if that is what your AOC demands. If the resultant deck angle bothers you (max pitch is 20 degrees from the Hawker AFM) then all you need to do is reduce power until you have a happy balance between deck angle and rate of climb. If you pitch for VFTO then you will have a limited drag penalty. If you pitch for anything less than 220 kts then you won't over speed the flaps. 160-180 kts and 90 per cent N1 works well for the Hawker, giving a good rate of climb and pleasant deck angle. I am slightly confused about all these pilots who are allegedly over-speeding the flaps; if both engines are running and you pitch for VFTO, controlling ROC with power, how can you over- speed the flaps?
Finally, the Flight Safety manual suggests 400' and VFTO as the flap retraction point, presumably as a belt and braces safety measure. There is no mention of 400' in the approved AFM, although the two are often achieved at about the same time. The AFM for your type will tell you how the aircraft should be flown to achieve a desired outcome. Your Authority and company AOC may require a different procedure, possibly for standardisation reasons. If there is a situation whereby the AOC requirements cause your type to be flown outside the limitations of the AFM or in an unnecessarily inefficient manner then you should make this known to your bosses such that the AOC can be amended.
AP