Accident Sequence
A pilot departed at 0638, initially drawing fuel from the left main tank. At 0739, he switched to the right main tank, and at 0840, he switched to the auxiliary fuel tank. Approaching his destination, the pilot noted that the main fuel tanks were half full and the auxiliary tank was over half full. He reduced power and began a slow descent.
Upon entering the traffic pattern, he switched back to the left main fuel tank. During the approach, he lowered the landing gear and began to lower the flaps. As the flaps extended, the airspeed decreased, prompting the pilot to add power. The airplane then "started to wobble and became hard to handle," so he applied full power. The airspeed "was not responding very quickly." The pilot confirmed the fuel selector was on the left tank and the fuel boost pump was on.
After clearing a rock wall cliff and ravine, the pilot flew underneath power lines, and the airplane struck the ground.
Post-Accident Testing
Flow testing of the carburetor at 10 psi revealed an external leak at the idle diaphragm. Further tests indicated the carburetor would run rich at low power settings and lean at high power settings. The fuel pump was able to maintain 20 gph at 10 psi and 500 rpm. At 1,000 rpm, a leak was noted at the lower splitline surface. At 2,500 rpm, the fuel pump maintained 160 gph at 12 psi.