On December 15, 1996, about 1256 eastern standard time, a Bell 47G, N1200Z, registered to Don l. Aircraft Inc., operating as a 14 CFR Part 91 personal flight, experienced a reported stuck throttle and engine overspeed while in the traffic pattern at Lantana, Florida. The pilot entered autorotation and crashed. Visual meteorological conditions prevailed and no flight plan was filed. The helicopter was destroyed by a postcrash fire. The airline transport pilot and one passenger reported minor injuries. The flight originated about 10 minutes before the accident. The pilot stated that as he was descending on right base for landing, the throttle stuck and the engine started to overspeed. He entered autorotation and turned into the wind. He did not initiate a deceleration. The helicopter collided with the ground in a nose-high attitude, bounced, nosed over, and came to rest inverted. Examination of the throttle assembly by the FAA revealed no deficiencies.