[2001 ZTS]

My edumacated guess....................

despite tonight's news reports that seem to now rule out lightning and the shift of cause to hydroplanning I say the airplaine had a static charge built up in flight, busted a rubber tire (which would normally insulate a plane) during a difficult landing and then there was metal to earth contact at the landing gear.

I'll even go so far and say it was rear landing gear and water and foam could control the initial fire but not put out the deep seated fire (which seemed to burn an unusually long time?) because it was "Class D" (metallic). Airplane wheels are often magnesium.

If you've seen magnesium burn you'll understand, it's the main ingredient in flares.

I had a friend that died for the same reason reversed. She was a stewardess and the front wheel bearing heated so much on take off that the magnesium burned unknown to the pilot who retracted the landing gear and the whole plane went down. That time everyone died.