Accident Sequence
While descending and at an altitude of about 900 feet msl, in preparation for entry into the traffic pattern at the airport, the pilot reported that the aircraft commenced an abrupt, uncommanded roll to the right. She regained level flight by applying full left aileron and full left rudder; however, the airplane remained in a right wing low attitude and in a gradual right turn. The pilot stated that she realized that directional control was compromised. Due to the high density of housing in the area of the airport, she elected to attempt a forced landing in a cow pasture. After landing, the airplane impacted a drainage ditch.
Post-Accident Examination
Examination of the airplane's fuel system after the accident revealed that the fuel tanks were not breached. The left fuel tank was full of fuel, and no fuel was found in the right fuel tank. The fuel selector handle was found positioned on the "right tank." About 1 ounce of fuel was drained from the forward fuel filter, and about 1/3 of a pint of fuel was drained from the aft fuel filter. Examination of the flight controls revealed that they operated normally and were found to be in serviceable condition. Examination of the propeller revealed that one propeller blade was bent aft 30 degrees and scratched, while the other blade was straight and clean.