WPR24LA230

The pilot departed the airport, after estimating with a calibrated stick that the airplane had 20 gallons of fuel in the left tank and 1/2 gallon of usable fuel in the right tank, for a 13-minute flight to the airplane’s home airport. The pilot selected the left fuel tank for the flight. About 3 minutes into the flight, or about 6.5 miles from the airport, he received indications of an insufficient rate of electrical charge; he did not attempt to reactivate the alternator as outlined in the Pilot’s Operating Handbook but elected to return to the airport. ADS-B showed that the airplane, which was about 6.5 miles southwest of the airport, then turned left 180° followed by a shallow continuous left turn for the next 5 miles while maintaining an altitude of about 6,400 ft msl. The airplane then turned right and began to descend toward the airport, entering the base leg for runway 26. The pilot then prepared to lower the gear manually due to the low voltage indication when, “seconds later,” the engine lost power. Once the landing was assured, the pilot lowered the landing gear handle, which activated the battery-driven hydraulic pump that controlled the landing gear system. The pilot reported that, after touchdown and despite his control inputs, the airplane veered sharply left, then sharply right, before exiting the runway into gravel. The impact with terrain substantially damaged the left horizontal stabilizer and elevator. Postaccident examination of the airplane’s fuel system revealed that about 6 gallons of fuel remained in the left wing tank and no usable fuel remained in the right wing fuel tank following the six-minute flight. The pilot reported that fuel was leaking from the left wing and front cowl after the accident, until the airplane was moved. According to the manufacturer, the last 0.5 gallon of fuel in the tanks are unusable. A test run of the engine revealed that it operated normally. The examinations revealed no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. The pilot reported that the airplane had an electrical issue before the annual inspection and suspected the alternator, which was replaced in 2020. Engine data monitor (EDM) data confirmed that after takeoff there was a continuous loss of battery voltage while the flight progressed. During the postaccident examination, one wire and a grounding strap were movable with hand force; however, the alternator and voltage regulator tested normally, and the alternator field circuit breaker was secured in place. No reason for the loss of voltage could be determined. The low battery voltage was insufficient to power the hydraulic pump to fully extend and lock the landing gear, which resulted in its collapse upon touchdown. The EDM data also revealed that, while the airplane was on the base leg to land and immediately before the loss of engine power, a reduction in fuel flow was followed immediately by an increase in engineexhaust gas temperatures. Such an increase is consistent with a lean fuel-to-air mixture, as often occurs during the initial phases of a fuel exhaustion or starvation event. ADS-B data showed the airplane maneuvered continuously during the return portion of the flight; the airplane likely entered sufficient uncoordinated flight while maneuvering to uncover the left wing fuel tank’s supply outlet, starving the engine of fuel and resulting in the total loss of engine power.

On June 13, 2024, about 1510 Pacific daylight time, a Cessna P210N, N36RW, was substantially damaged when it was involved in an accident near Reno, Nevada. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that an annual inspection had been completed on the airplane, which included an inspection of the electrical system and the replacement of the alternator field circuit breaker. On the day of the accident, he was returning the airplane from the maintenance facility located at Reno/Stead Airport (RTS), Reno, Nevada, to Carson City Airport (CXP) Carson City, Nevada. During the preflight inspection, he used a calibrated stick to estimate the airplane’s left-wing tank contained about 20 gallons of fuel and the right-wing fuel tank contained about 1 gallon of fuel. He selected the left fuel tank on the fuel selector. He reported that the planned flight would be about 13 minutes in duration and that the fuel quantity was adequate. According to the pilot, he departed on runway 26. ADS-B data showed the airplane departed about 1503, turned south and climbed to 6,700 ft mean sea level (msl). During the takeoff climb, the EDM data showed all engine indications were consistent with normal operations. About 1 minute later, the voltage began to reduce from 28 volts and continued to reduce throughout the remainder of the flight, reaching about 11.6 volts near the end of the 7-minute flight. The pilot reported that the battery alarm activated, and he saw that the alternator circuit breaker had opened. He closed the circuit breaker and then saw the battery voltage dropping rapidly and the ammeter showed a discharge. He elected to return to the airport and prepared to lower the gear manually due to the low voltage indication. According to the pilot, “seconds later,” the engine lost power. About 1506, ADS-B showed that the airplane, which was about 6.5 miles southwest of the airport, turned left, 180°, followed by a shallow continuous left turn for the next 5 miles while maintaining an altitude of about 6,400 ft msl. The airplane then turned right and began to descend toward the airport, consistent with entering the base leg for runway 26 (figure1). Figure 1. Google Earth image showing the ADS-B path of the accident flight. EDM data showed that from 1508:53 to 1509:17 the fuel flow reduced from 19.7 GPH to about .1 GPH and the exhaust gas temperatures increased from a range of 1306-1384°F to a range of 1478-1579°F at 1509:05 before decreasing. At that time, the airplane was about 1 mile from the approach end of runway 26 at an altitude of about 760 ft above ground level (agl). After determining that a landing was assured, the pilot lowered the landing gear using the landing gear lever, which activated the electrically powered hydraulic motor, lowering the gear. According to the pilot, during the touchdown the airplane veered to the left. The pilot attempted to correct backto the runway. The airplane then veered to the right and departed the runway surface onto gravel. Postaccident examination revealed that the landing gear had collapsed and contact with the ground substantially damaged the left horizontal stabilizer and left elevator. The pilot reported that after the accident, he witnessed fuel leaking from the left-wing tank and front cowling. Postaccident examination of the airframe revealed that about 6 gallons of fuel remained in the left-wing tank and about 1 gallon remained in the right-wing tank. A test run of the engine revealed the engine started and ran without abnormalities. Examination of the electrical system revealed the alternator remained secured to its mounting pad to the engine. All electrical wires to and from the alternator were secure. One wire attached to the ground service contactor could be moved at its attachment point with hand force, and the alternator ground cable strap could be moved at its attachment point with moderate hand force. The alternator was tested and found to operate normally. The voltage regulator was tested using the manufacturer’s guidance and found to operate normally. A visual inspection of the circuit breaker panel revealed all circuit breakers were securely installed in the panel, with no loose wires. The battery was charged and did not lose voltage during the examination. Examinations revealed no preaccident mechanical malfunctions or failures with the airplane that would have precluded normal operation. The pilot reported that the alternator had a suspected problem and that it was on a squawk list before the annual inspection. A review of maintenance records revealed that on June 13, 2024, an annual inspection was completed, along with an inspection of the electrical system and the replacement of the alternator field circuit breaker. On December 16, 2020, a new battery, and a newly overhauled alternator were installed on the airplane. According to the Pilot’s Operating Handbook (POH) Emergency Procedures for insufficient rate of charge, “If the overvoltage sensor should shut down the alternator, or if the alternator output is low, a discharge rate will be shown on the ammeter followed by the illumination of the low-voltage warning light. Since this maybe a “nuisance” trip-out, an attempt should be made to reactivate the alternator system. To do this, turn the avionics power switch off. Check that the alternator circuit breaker is in, then turn both sides of the master switch off and then on again. If the problem no longer exists, normal alternator charging will resume, and the low-voltage light will go off. If the light illuminates again, a malfunction is confirmed. In this event then the flight should be terminated and/or the current drain on the battery minimized because the battery can supply the electrical system for only a limited time… In any case, battery power must be conserved for later operation of the landing gear and wing flaps…” The POH also statedthe following, “Fuel quantity, 1.5 gallons unusable fuel in each tank.” The Cessna Pilot Safety and Warning Supplement, dated June 1, 1998, stated, in part, “The shape of most airplane fuel wing tanks is such that, in certain flight maneuvers, the fuel may move away from the fuel tank supply outlet. If the outlet is uncovered, fuel flow to the engine may be interrupted and a temporary loss of power might result. Pilots can prevent inadvertent uncovering of the tank outlet by having adequate fuel in the tank selected and avoiding maneuvers such as prolonged uncoordinated flight or sideslips which move the fuel away from the feed lines. As a general rule, limit uncoordinated flight or sideslips to 30 seconds in duration when the fuel level in the selected fuel tank is ¼ full or less. Airplanes are usually considered in a sideslip anytime the turn and bank “ball” is more than one quarter ball out of the center (coordinated flight) position. The amount of usable fuel decreases with the severity of the sideslip in all cases.“