19980519010179A

(.4)The pilot reported that as the airplane was descending through 4,000 feet MSL it started loosing power. She leveled off, pulled carburetor heat on, and switched fuel tanks. She reported that, 'upon restart the engine backfired and quit.' She reported that she trimmed the airplane for best glide (80 mph) and flew directly for the airport 2.5 miles away. At .5 miles from the airport she realized she would not make the runway so she decided to land short. She set 10 degrees of flaps and landed in a field. The airplane hit a wooden fence post during landing roll in the muddy field and nosed over. An examination of the engine found the induction system balance tube separated from the intake manifold tube assembly. The induction system balance tube coupling did not line up with the intake manifold. The engine was test run. During the first test run, the induction system balance tube coupling was left disconnected. The engine started but would only run when the throttle was continuously pumped. The balance tube coupling was connected and the engine restarted. The engine operated and did not require continuous pumping of the throttle. The engine was run up to 1,700 RPM. Th e engine ran smoothly at 1,700 RPM with no missing or backfiring. No other pre-impact mechanical anomalies were noted on the engine. (-23) see attached; no narrative attached.