Pilot Report
The pilot reported that while descending through 4,000 feet mean sea level, the engine began losing power. She leveled off, engaged carburetor heat, and switched fuel tanks. According to her account, upon attempting to restart, the engine backfired and quit. She trimmed the airplane for best glide at 80 mph and headed directly for an airport located 2.5 miles away. When she was half a mile from the airport, she determined that she would not reach the runway and decided to land short. She set 10 degrees of flaps and touched down in a field. During the landing roll, the airplane struck a wooden fence post in the muddy terrain and nosed over.
Engine Examination
An examination of the engine disclosed that the induction system balance tube had separated from the intake manifold tube assembly. It was noted that the coupling of the induction system balance tube did not align properly with the intake manifold.
Test Run
A test run of the engine was conducted. During the initial test, the induction system balance tube coupling was left disconnected. The engine started but would only run when the throttle was continuously pumped. After connecting the balance tube coupling and restarting, the engine operated without requiring continuous throttle pumping. The engine was run up to 1,700 RPM and ran smoothly with no missing or backfiring. No other pre-impact mechanical anomalies were identified on the engine.