The pilot reported that, while taxing with a tailwind, he realized the airplane was moving too fast and applied brakes and reverse thrust of the engines. He added that he attempted to turn but was unable, and a strong crosswind “forced” the airplane to the left and off of the airport parking ramp. Subsequently, the airplane struck a lamp post and came to rest. The airplane sustained substantial damage to the left wing. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The automated weather observation system located at the accident airport reported, that about the time of the accident, the wind was from 280ø at 21 knots, gusting to 27 knots. PROBABLE CAUSE: “The pilot’s failure to maintain directional control while taxiing in gusting tailwind conditions.”