there was another member here who reported a broken drum in a model similar to yours, so maybe they are prone to that.
It was named Brian..
Gotta confess it's first time I hear and see such a thing, my only guess is that drum got it's welding failed (it enlarged) and while spinning the drum holes finishes on the other sides makes sparks touching the outter tub, though still weird being clothes mosit to be scorched like that, but you should be able to see if the the welding point failed and now drum will touch the outter tub during spin and makes sparks...
Try to make it spin empty also for some seconds! It sure will make a terrible noise.
My first guess was that your machine had a sort of fail in the timer sending current to the heater while spinning, but your model shouldn't have an heater....it's not a combo washer dyrer either...so...
If it were the drum that would have heated for some very weird reasons the holes should have been white and all the rest scorched...but here is something happened in the outter tub!