On May 13, 1994, about 1210 eastern daylight time, a Piper J3C-65, N114WW, registered to Thomas W. Merrifield, collided with trees during a precautionary landing on a golf course near Belleair, Florida, while on a 14 CFR Part 91 banner towing flight. Visual meteorological conditions prevailed at the time and no flight plan was filed. The airplane was substantially damaged and the commercial-rated pilot sustained minor injuries. The flight originated at St. Petersburg, Florida, on May 13, 1994, about. The pilot stated that about 15 minutes after takeoff the engine began to lose oil. He released the banner and initiated a descent to land on a golf course with the windshield covered by oil. After touchdown he observed a ditch ahead and added power to clear it. He was then unable to stop before colliding with trees. Postcrash examination of the engine by FAA inspectors indicated the engine front crankshaft seal was partially dislodged causing the oil leakage. The engine case breather line was found partially blocked by oil sludge and debris. No other evidence of failure or malfunction was noted.