Navion G N2473T

The commercial pilot was traveling to attend an air show the following day. Upon arrival at the destination, he attempted a night instrument landing system approach but, due to low visibility, flew a missed approach. He subsequently requested and received vectors for a second attempt of the same approach. However, as the airplane neared the final approach course, the controller advised the pilot of worsening weather conditions, and the pilot then requested vectors to an alternate airport. After receiving a clearance, the pilot added power to the engine and initiated a climb, but the engine lost power, which the pilot attributed to either a fuel or an electrical problem. The airplane subsequently descended into trees and stuck the ground nose-low, on its left side, in a "violent deceleration." The pilot stated that he had checked the fuel quantity in both of the airplane's wing tip tanks and the connected main tanks before the flight using a calibrated stick and found about 10 gallons of fuel in each tip tank and 15 gallons of fuel in the main tanks. He also stated that he always took off and landed using the main fuel tanks and used the tip tanks in transit. The pilot further stated that, during the flight, he used the left tip tank for 22 minutes 40 seconds and was certain of the time because he used a stopwatch. He then used the main fuel tanks for the first approach and, after the missed approach, switched to the right tip tank. About 1 minute before the engine quit, he switched from the right tip tank to the main tanks again. Once the engine quit, the pilot moved the fuel selector through various positions and then checked the ignition, throttle, and mixture. The airplane was equipped with an engine monitor, which, among other parameters, tracked fuel flow. Data revealed that, at one point, fuel flow dropped to 0, with a concurrent reduction in all engine temperatures. Before the end of the recording, fuel flow spiked briefly up to 4 gallons per hour on four occasions before returning to 0, consistent with the pilot's statement that he moved the fuel selector to different positions. Two of the spikes occurred for 2 seconds, and the other two occurred for 3 seconds. The pilot reported that, after intentionally running a tank out of fuel during en route operations, the engine would restart about 5 to 10 seconds after switching fuel tanks. At the accident site, fuel was found in all tanks except the left tip tank. Although compromised upon impact, there was no evidence of fuel leakage underneath or in the vicinity of that tank. Fuel supply system continuity, with no blockages noted, was later confirmed from all tanks to the engine, and after replacing some impact-damaged items, the engine was run from idle to full throttle multiple times with no anomalies noted. Although fuel was not found in the left tip tank at the accident site, a small amount was likely still present when the pilot initiated the climb after the missed approach, which then sloshed toward the aft end of the tank, unporting the fuel pickup. This introduced air into the engine fuel supply, which led to the loss of engine power. The lack of fuel found in the left tip tank, the absence of anomalies noted in either the fuel supply system or when the engine was test run, the cessation of fuel flow noted in the engine monitor data, and the fluctuation of fuel flow as the pilot subsequently moved the fuel selector through the tanks-with-fuel and tank-without-fuel positions cumulatively indicated the likelihood that the pilot inadvertently moved the fuel selector to the left tip tank when he began the climb to the alternate airport and was operating the engine from an almost depleted left wing tip tank when the engine lost power. The airplane was manufactured at a time when only seat belts were required; front-seat shoulder harnesses or other restraints with an equal level of protection were not mandatory. The airplane did not have shoulder harnesses at the time of the accident, and the Federal Aviation Administration does not mandate retrofit, instead relying on voluntary installation. The pilot-rated passenger in the right front seat was fatally injured when her head impacted the engine controls and instrument panel, an outcome that likely would have been mitigated with the presence and use of adequate shoulder restraints or other equal-level protection.

Quoted verbatim from the NTSB record.