Single-engine failure? Low down, low thrust, gusty cross-wind, down-draught/windshear.....could be tricky for the A/THR and PF to handle. Might explain steep bank angle and noise from one engine. I know, I know, this shouldn't cause an undershoot of such proportions, and this is mere speculation. Hope fully all will be revealed from the FDR and CVR.
Nope. not true.
A single engine failure at that stage of flight is irrelevant. Even from a autopilot/autothrottle point of view.
I specifically remember being in the simulator for my conversion training to the B777, and the instructor gave me an engine failure at 500 feet, on short final. The autothrottle and autopilot were engaged, because the weather was Cat III. result? uneventful landing, autoland.
Conclusion: a single engine failure at 500 feet is more or less irrelevant, and will not make a whole lot of difference.
Also, a single engine failure will not any handling difficulties. The 777 is always in trim. As long as the airspeed remains the same before/after the single engine fails, the airplane is still in trim. there is an automatic trrim system installed. so no handling problems there. Furthermore, the autothrotlle is very "agressive" and will react firmly to the single engine not providing any thrust. It only needs to add about 7% N1 to compensate anyway on a 3 degree glidepath.