The Koala is powerful, but does not perform very well at high density altitudes. After having a look at the performance charts it looked like that aircraft was close to 800 lbs over gross weight under the given conditions that day. Take this with a grain of salt because there are a few unknown factors there. There's a video out from the local news in that area that showed the wreckage and it looked like it had just fallen out of the sky and colapsed. The blades were still intact (broken, but still attached to the air frame) and the tail boom was cracked right around the attcahement points to the main frame, indicating that the blades had not made contact with the tail boom. This, off course, is just speculations from my side. I am not an accident investigator.