The petrol thing on-site is always an interesting one. As Avgas evaporates so quickly if the tank(s) were ruptured the Avgas wouldn't last long on a hot day before evaporating. The MM has a very small fuel capacity anyway, possibly less than 2 hours total in practice. A little too soon to speculate on that given the lack of credible witnesses.
Myths to be busted:
- Aircraft don't always explode when they crash even with fuel on board
- Aircraft don't fall out of the sky when the engine stops
There are also very few electrics on the MM and if I'm not mistaken, it's cranked by hand which could explain the lack of a fire, not taking into consideration exhaust heat etc as a source of combustion.