While enroute to the staging area to drop the banner, the engine, without warning, appeared to accelerate into an over-speed condition. Seconds later, the engine lost power and quit. The airplane collided with a utility line as the pilot maneuvered the airplane for a forced landing. Examination of the engine revealed, that the number six-piston arm assembly broke through the engine case. There was no oil in the engine and the engine had seized. The engine had undergone recent major repairs.