Tuning Issue

Hi. I have a ARDrone Quadcopter with APM1. I have gotten it pretty well tuned up and stable with one exception that I am not sure what knob to tweak to get it right. Its flies stable except when I lower the throttle to land or bring down the altitude, it will just flip instantly and completely slam. Obviously I can not do a lot of trial and error on this, because the error is a complete rebuild since it body slams into the ground. When holding it and giving it a little throttle it seems to just shut down a motor or motors when off tilt a little instead of ramping down, I suspect this is what is happening in flight. Although it happens so fast it might be reversing a motor… I am running in stabilize mode. It runs real smooth and responsive when its above 1/3 or 1/2 throttle, its a low speed thing. Hopefully someone can help me out. I am a newbie so please provide some details on what I can do.

You might have an ESC calibration problem. You might want to recalibrate your ESCs: copter.ardupilot.com/wiki/initia … esc-motor/