It may be 70%, it may be 35% - the fuel control still is programmed to avoid compressor stall, and that's the limiting speed for the engine in that degraded state.
So the engines (as I see it) WERE NOT at a governed, stabilized idle, even though the gages might have suggested that. They were trapped by their degraded steady-state line intersecting the accel schedule.
As a layman when it comes to turbines, is this aspect of the event a control system design failure (under extreme circumstances) to command delivery of fuel?
If so, would a "bird strike" button that is programmed to deliver appropriate amount of fuel regardless of any other sensor inputs be a good idea?
mickjoebill