If someone could come up with a small turbine that had reasonable purchase cost and more importantly overhaul costs then it would be possible.R44 is currently 310K USd extra purchase cost with current certified turbines would be closer to 500 K usd ( Engine exchange cost is 21K allison 250 is closer to $200 k ). Operating cost is 124 USd/hr , turbine overhaul reserve would add minimum of $50 an hr. The Enstrom turbine has not been exactly flying of the shelves .