I would think there are already a bunch of biofuel ready helicopters. Turbine helis burn Jet-A. Anything that'll burn that will likely burn biodiesel.
The issues between burning biodiesel in your turbine helicopter and today are largely regulatory, not technical.
Pour 80 gallons of biodiesel in the Long Ranger, and it'll fire right up I bet. Probably with fewer issues than your Powerstroke or Mercedes.