Yeah, my immediate thoughts are that a chunk of metal/wood/plastic going through a thin cable in the region of 70Mph would have no problem in destroying it, but that's just a naive guess! Again, it would depend on where the cables came into contact with the aircraft - for example if hitting the undercarriage, this could result in a forward jerk.
Actually - this reminds me of an accident that occurred (think it was in the states) when a light aircraft became entangled in power cables (I think) and it was left hanging up-side-down for some time. I haven't found any web link to this yet.......