What happened
While descending approximately 4 miles north of San Antonio International Airport (SAT), the aircraft suffered a loss of engine power. During the descent, a pilot-rated passenger manipulated the flight controls while the pilot attempted to perform an unsuccessful engine restart. The aircraft eventually came to rest in a grassy field located about 1 1/2 miles northwest of runway 12L, situated near trees and power lines.
The investigation
An examination of the engine and the aircraft revealed no structural or mechanical defects. Investigators performed testing on the engine-driven fuel pump accessory, which was found to be flowing fuel from the overboard drain at a rate of 0.5 gallons per minute, though it continued to pump fuel to the engine at 25 PSI and 275 lbs/hr.
An on-site inspection confirmed that usable fuel remained in both wing tanks. A teardown of the fuel pump revealed that the 'O' rings were worn and had developed square cross sections. Furthermore, investigators found non-metallic debris in the fitting of the fuel servo inlet screen, and the screen itself was partially clogged. Despite these findings, the anomalies identified within the fuel system accessories were considered inconclusive.