Initially, the NTSB thought it might never determine the cause of the Pilatus crash at Butte, reporting to the press that it had no working theories. But this week, the NTSB concluded that the 2009 crash was caused by icing in the aircraft’s fuel system. According to the NTSB, the pilot failed to add an ice inhibitor to his fuel before takeoff. Then, when his fuel started to solidify at altitude, he failed to immediately land. Fuel in one wing tank began to freeze. With fuel draining to the engine from other wing tank only, a fuel imbalance developed and grew worse and worse. The fuel imbalance ultimately rendered the aircraft uncontrollable, and the pilot crashed.
Interesting analysis. But a blog reader provided us this analysis eight months ago, in a comment to this post. Looks like "Pilatus Person" was spot on:
Pilot didn’t take on Prist. Without Prist, the fuel the pilot had on board would freeze at -40F. It was colder than that at pilot’s altitude. So fuel in one tank turned to jello. Despite the transfer pump’s best efforts, it couldn’t move fuel from that tank to the other side to balance the load. Pilot asked for a lower altitude because he wanted warmer air. But by then, the tanks were seriously out of balance. Pilot had to hold one wing up with aileron. As he approached the field, he was cross-controlled. Then he turned in the "wrong" direction. A cross-control stall flipped the aircraft on its back. . . .All of that fits with the information in the docket. Check it out.