There has been discussion about Harold and Maude seeing the plane on fire or hearing sputtering, and I agree, you almost always get "witnesses" that say that. In this case, I think there may be some truth to the matter. As mentioned previously, the plane clipped the power lines (and trees) before impacting the hill. This could have ruptured a fuel tank and the impacted electrical lines could have ignited it. From the insulators I can see in the photos, it looks like that there is 12KV service in that area, so the arcing could have been significant.
I also think that the "sputtering engines" may have been the sound of high voltage arcing, spring fuses melting, or the utility recloser in operation....
Maybe...but I don't think the power line part is likely.
I drove by the accident 3 times and didn't see any power line that were hit directly by the plane. I think the power lines were damaged by tree brush being knocked down. The trees there are close to 70-80 feet in height. Also, one other thing I saw that seemed to stand out. From a saving it (or at least improving your crash circumstances) point of view, only the last tree looked large enough to cause significant structural damage, which would have only affected one side or one engine. I would think they would have gone to TOGA at least when they started to hit the smaller trees which were at a similar altitude to the impact at on the hill and about 1000 to 1200 feet before. That's only about 6 to 8 seconds. Also, in the overhead pictures it's hard to see how steep the hill is, but the impact angle was probably at least 20 degrees due to the slope of the hill. If they had 20 more feet of altitude, they would have had a much better chance of surviving.
I also think the comparisons to Asiana don't have much value at this point, since the conditions seem quite different.