Centralia, IL, USA
N8466A
BEECH A35
The pilot had purchased the airplane about 3 months before the accident and, according to his logbook, had accrued about 17 hours of flight experience in the airplane. The airplane departed for a cross-country flight with the fuel selector in the LEFT fuel tank position, which was consistent with guidance from the pilot’s operating handbook. About 1 hour 13 minutes into the flight, as the airplane approached an airport while at 6,500 ft, the pilot attempted to switch to the RIGHT fuel tank. The pilot had wanted to switch fuel tanks “just in case” because he “didn’t trust the wobble pump” (a manually operated auxiliary fuel pump that is integrated with the fuel selector valve). He recalled that it was “hard to feel the detents” in the fuel selector valve and that it was “possible that it [the fuel selector valve] was not fully engaged.” About 4 to 5 minutes after switching fuel tanks, the engine lost power. The pilot noted that the engine RPM was at 1,500 and believed that it had sufficient power to fly a traffic pattern to the runway. However, the engine was likely instead windmilling, with no power. The pilot turned around, flew past the nearest end of the runway at the airport he just overflew, and attempted to fly a left traffic pattern toward the runway’s opposite end. However, during the approach, the airplane “got too low,” and there was “no place to land.” The airplane continued to descend and then impacted terrain. The wreckage was located about 0.5 nautical miles north of the runway threshold. After the accident, the pilot stated that, in hindsight, he should have made a straight-in approach to the nearest end of the runway and slipped the airplane to descend. Given the airplane’s altitude and proximity to the airport, had the pilot done this, it is likely that the airplane would have landed on the runway. Examination of the airplane revealed that the fuel selector handle was not fully in the down position. When pushed fully downward, the fuel selector handle engages the fuel selector valve. When rotated in this position, the fuel selector handle can select either the LEFT or RIGHT fuel tank. When the fuel selector handle is pulled upward, it disengages from the fuel selector valve and can then be used as a manual fuel pump. Although the pilot reported using the handle in “pump mode” after the loss of power, the handle was also likely in “pump mode” when he rotated the handle to switch to the right fuel tank. While in this mode, rotating the handle would have no effect on the fuel selector valve, indicating that the handle likely remained in the LEFT fuel tank position. In addition, the pilot stated that it was difficult to detect the fuel selector valve detents, but postaccident examination showed that the detents could be felt when the fuel selector valve was engaged and rotated. An electrical switch that was intended to warn the pilot, via a light on the instrument panel, when the fuel selector handle is not fully down and engaged with the fuel selector valve, was found not installed and stored in a map pocket in the cockpit. A Federal Aviation Administration airworthiness directive required the installation of this switch and cockpit warning light, (or the replacement of the selector valve/pump mechanism with one that has separate fuel selector and pump controls). If this switch had been installed, it would likely have warned the pilot that the fuel selector handle was in “pump mode” and was unable to change fuel tanks when rotated. Fuel usage calculations indicated that the fuel burn for the flight was likely 16.2 gallons or greater, leaving less than 1 gallon of usable fuel in the left fuel tank. Therefore, the loss of total engine power was likely due to fuel starvation when all the fuel in the left fuel tank expended.
On July 23, 2022, about 1238 central daylight time, a Beech A35, N8466A, was substantially damaged when it was involved in an accident in Centralia, Illinois. The pilot was seriously injured, and the passenger was fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had purchased the airplane in April 2022. According to the pilot, the accident flight departed Marshall County Airport (C75), Lacon, Illinois, with the fuel selector set to the left tank. About 1 hour 13 minutes into the flight, the airplane was near Centralia Municipal Airport (ENL), Centralia, Illinois, while at a cruising altitude of 6,500 ft mean sea level and on a southerly heading. At that time, the pilot switched the fuel selector to the right tank “just in case” because he “didn’t trust the wobble pump” (a mechanism combined with the fuel tank selector valve). The pilot recalled that it was “hard to feel the detents” in the selector valve and that it was “possible that it [the selector valve] was not fully engaged.” About 4 to 5 minutes later, the engine lost total power. The pilot reported that the engine did not “sputter” and that he noted no abnormal indications before the loss of power. He stated that engine power reduced to 1,500 rpm and that the engine and propeller noise decreased. The pilot realized that the airplane had just overflown ENL, so he made a right turn to reverse course and land there. The pilot thought that, with engine power at 1,500 rpm, the airplane would have sufficient power for a left traffic pattern to runway 18. The pilot stated that he pumped the manual hand “wobble” fuel pump “fast,” but engine power was not restored. He flew past the nearest end of the runway and continued to fly the left traffic pattern toward the opposite end, until the airplane “got too low” with “no place to land.” The engine power “dropped” further, and the airplane descended until it impacted terrain. The pilot did not recall if the propeller continued to rotate. After the accident, the pilot stated that, in hindsight, he should have made a straight-in approach to the opposite end of the runway and slipped the airplane to descend. Figure 1 shows Federal Aviation Administration tracking data for the last 8 minutes of the flight. Figure 1. Data showing last 8 minutes of flight (Source: Federal Aviation Administration). A review of the pilot’s logbook revealed that he had completed eight flights in the accident airplane (six of which were with an instructor) for a total of 16.5 flight hours. The pilot reported that the only recent maintenance performed on the airplane was the pre buy inspection and the replacement of a light bulb for the landing gear up indicator. The fuel selector/pump mechanism is located just forward of the pilot’s seat at the left side of the fuselage. The fuel selector handle doubled as the auxiliary (wobble) fuel pump handle. When the handle is fully in the down position, the handle engages the fuel selector valve. In this position, rotating the handle left or right moves the fuel selector valve between the left or right fuel tank (or OFF) positions. If the handle is not fully down, it will not engage the valve, and rotating the handle would have no effect. Figure 2 shows the handle from the accident airplane as well as the placard indicating that each of the airplane’s two fuel tanks had a capacity of 20 gallons (17 gallons of which was usable). Figure 2. Fuel selector/wobble pump handle and placard. When the handle is lifted slightly upward, it becomes disengaged from the fuel selector valve. With the handle in this “pump mode”, the pilot can then move the handle up and down (like a small bicycle pump) to pressurize the fuel system. The pump is normally used during engine start. It can also be used in an emergency if the engine-driven fuel pump fails. If a fuel tank was completely dry, starving the engine of fuel, the pump can be used after switching to another fuel tank to maintain fuel pressure and aid in restarting the engine. Fuel records indicated that the pilot added 1.85 gallons of fuel to the airplane before departing C75, and surveillance camera images showed that fuel was added to the right-wing tank only. Fuel burn estimates (based on the Beech A35 and B35 pilot’s operating handbook) for ground operations, cruise performance, and flight duration yielded a burn of 16.2 gallons, not including the increased fuel flow during the climb. The pilot’s operating handbook also stated that takeoffs “should be made using the left main tank and landings should be made using the main tank that is more nearly full.” Examination of the accident scene revealed a 100-ft-long debris path that began at a 50-ft tree and continued along a true heading of about 265°. The debris path contained broken tree branches that led to the main wreckage, which came to rest in a residential backyard above an in-ground swimming pool. The fuselage was oriented on a heading of about 100° and was located about 0.5 nautical miles north of the runway 18 threshold and about 0.2 nautical miles left of the extended runway centerline. The engine was found partially separated from the fuselage. Examination of the airplane revealed that the right wing sustained leading-edge crush damage along most of its span. A semicircular-shaped gouge about 2 ft inboard of the right wing tip contained leaves and small branches. The left wing sustained leading edge crush damage along most of its span, with paint transfer marks consistent with the color of the pool’s rim cap. The wing structure surrounding the fuel tank bladders was mostly intact. The fuel filler caps were secure and undamaged. About 15 gallons of fuel was recovered from the right fuel tank, not including an undetermined amount of fuel that spilled when the fuel cap was removed for examination. About 2.5 gallons of fuel remained in the left tank. The fuselage was buckled on both sides near the roof, aft of the baggage door and aft windows. The remainder of the empennage was mostly undamaged. The lower forward section of the fuselage was crush damaged forward of the wings. The flaps and landing gear were in the retracted positions. The fuel selector handle was found partially extended (upward in the pump operating position). The handle was found rotated toward the RIGHT fuel tank position; the fuel selector valve was found in the LEFT fuel tank position. An electric switch mechanism, designed to illuminate a warning light on the instrument panel when the pump/fuel selector handle was disengaged from the fuel selector valve, was found unattached from the selector valve/pump mechanism and stored in a cockpit map pocket. A 1969 Federal Aviation Administration airworthiness directive (AD 69-18-01) required either the installation of this switch and cockpit warning light or the replacement of the mechanism with one that had a separate fuel selector and pump controls. The airplane was recovered to a salvage facility for further examination. Flight control continuity was confirmed from the cockpit controls to all flight control surfaces. The fuel selector valve/wobble pump assembly was removed. With the handle in the down/valve-engaged position, the handle rotated smoothy in both directions through 360°. Each valve position (LEFT, OFF, RIGHT, OFF) detent could be felt in the handle, and an audible click was heard for each detent. The valve operated normally when tested with compressed air. The wobble pump operated normally when tested with the input lines submerged in a container of fuel. The fuel filter screen was absent of debris. Both fuel tank bladders appeared to be intact. The fuel tank venting lines were intact except for some crushing damage to one line at the leading edge of the left wing. Compressed air passed through all portions of the vent lines except for the damaged line. The left fuel tank finger screen and attached fuel line were found pulled from the tank toward the fuselage. The screen was absent of debris. The right fuel tank finger screen was inaccessible. All engine controls, propeller control, and fuel lines remained attached to their respective locations on the engine. Examination of the engine revealed no anomalies that would have precluded normal operation.
The pilot’s unsuccessful attempt to switch fuel tanks, which resulted in fuel starvation. Contributing to the accident was the uninstalled fuel selector handle warning device.
Source: NTSB Aviation Accident Database
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