CEN19LA076

The pilot's fuel mismanagement and his improper use and placement of the fuel selector, contrary to operating procedures, which resulted in a partial loss of engine power due to fuel starvation.

The pilot departed with about 40 gallons of fuel on board and completed several flights to local area airports. After about 90 minutes of total flight time, the pilot departed the last airport and had flown a few miles when the engine began running roughly. He stated he switched the fuel selector back and forth between both fuel tank positions, turned the fuel pump on, and advanced the mixture to full rich, but the engine roughness continued. He performed an emergency landing to a road, during which the airplane hit a parked car. The right wing separated from the fuselage, and the airplane flipped upside down. Nine gallons of fuel were recovered from the left wing tanks, and the inboard right wing tank was found empty, with the right fuel cap secure on the wing. The outboard right wing tank was ruptured and the right wing fuel lines were compromised during impact, but no evidence of fuel from the right wing tanks was found at the scene. The on-scene examination noted that the fuel selector lever was found in an intermediate position between the left and right tank detents, about 1 to 2 inches past center, more toward the right tank position. Recovered engine data monitor (EDM) data associated with the accident flight showed a consistent decrease in cylinder head temperatures (CHTs) during the final 3 minutes of the recording, and exhaust gas temperature (EGT) data showed a series of temperature fluctuations during the same time period. The decreasing CHTs and varying EGTs were consistent with a rough-running engine with fluctuating engine speeds. Postaccident functional engine test runs were performed, and no anomalies were noted with the engine or fuel system. When the fuel system was configured to mimic fuel available in the left tank and no fuel in the right tank, engine roughness and a partial loss of engine power was duplicated through placement of the fuel selector lever to the approximate position as found at the accident scene. The engine roughness can likely be attributed to a mixture of fuel and air in the fuel system. It was not possible to compute exact fuel usage associated with all the engine operations on the day of the accident due to a lack of information regarding power settings and altitudes flown. However, computations using best economy and best power fuel flow rates for the 94 minutes recorded by the EDM resulted in fuel used of 21.62 gallons for best economy and 37.6 gallons for best power. Although the EDM did not record fuel usage, it is likely the airplane consumed sufficient fuel to empty the right tanks during operations on the day of the accident. The pilot's operating handbook states the electric fuel pump should be turned on before switching tanks, and, to provide continuity of fuel flow, the selector should be changed to another tank before fuel is exhausted from the tank in use. If signs of fuel starvation occur at any time during flight, fuel exhaustion should be suspected, and the fuel selector should be immediately positioned to a full tank and the electric fuel pump switched to the on position. It is likely that the pilot exhausted the fuel in the right tanks before switching tanks, contrary to the recommended operating procedures, which introduced air into the fuel system and resulted in a partial loss of engine power due to fuel starvation. Additionally, the pilot likely continued to switch between the left and right tanks, and ultimately placed the fuel selector handle between the left and right tank positions, instead of selecting and leaving the fuel selector on the left tank with available fuel. This allowed more air into the system and further reduced the fuel available to the engine.

The airplane had a total fuel capacity of 98 gallons. The usable fuel was 47.0 gallons in each wing tank (47.0 gallons is the total per side, each side having two interconnected tanks). The wreckage was initially moved to EDC, where it was stored outdoors with the left wing attached. It was relocated to a secure storage facility in Lancaster, Texas, on February 19, 2019. Recovery personnel retrieved 9 gallons of liquid consistent with aviation fuel from the left wing prior to removing it from the fuselage for transportation. The inboard right wing tank did not contain any fuel and the right fuel cap was secure on the wing when viewed at the accident scene by Federal Aviation Administration (FAA) inspectors. The right tank fuel lines were compromised where the wing separated from the fuselage during the accident, and the right outboard fuel tank was ruptured where leading edge impact damage had occurred. No evidence of fuel leakage from the right wing tanks was evident at the accident scene and no fuel was found in the right wing tanks by recovery personnel. FAA inspectors documented the fuel selector handle in a position about 1 to 2 inches past center towards the right tank position (see figure 2). Figure 2 - Fuel Selector Position An examination of the wreckage and functional engine test runs were conducted by the NTSB Investigator in Charge (IIC) and parties to the investigation on August 13, 2019. The fuselage with the engine attached had been loaded on a trailer and secured in preparation for an attempted engine run. The following observations were made during the post-accident examination at the storage facility. Fuselage The fuselage was upright and secured with ratchet straps on a trailer. The wings were separated from the fuselage. The stabilator flight control cables were continuous from the cockpit to the stabilator bellcrank. The rudder cables were continuous from the rudder pedal assembly to the rudder sector at the empennage. The continuity of the aileron flight control cables in the cabin was not established. The fuel selector handle was in the "LEFT" position and the control rods were intact and continuous to fuel selector valve which was also in the left tank position. Low air pressure was applied to the left and right tank inlet ports on the fuel selector valve which allowed air to pass when placed in both the left and right detents. The valve rotated smoothly and the detents were noticeable. In preparation for running the engine, the fuel line from the fuel selector valve to the electric fuel pump was disconnected and a flexible fuel line was connected to the inlet port of the electric fuel pump. This line continued outside the fuselage and was connected to a portable fuel container to facilitate running the engine. Left Wing The left wing was separated from the fuselage. The flap and aileron both remained attached to their hinges. The fuel filler cap was located in the fuel filler opening and was unremarkable. The fuel line fitting was disconnected from the outlet port of the inboard fuel tank and a borescope was used to look into the fitting and observe the fuel strainer. No debris was observed in the screen. Right Wing The right wing was separated from the fuselage. The flap was separated from the wing. The aileron remained attached to its hinges. The leading edge exhibited impact damage forward of the aileron and outboard of the outer fuel tank. The fuel filler cap was not accessible or examined due to the positioning of the right wing. The fuel line fitting was disconnected from the outlet port of the inboard fuel tank and a borescope was used to look into the fitting and observe the fuel strainer. No debris was observed in the screen. Empennage The vertical stabilizer remained attached to the tail cone and the rudder remained attached to the vertical stabilizer. The rudder stops were intact and unremarkable. The stabilator had been removed from the vertical stabilizer. Engine The engine remained attached to the truss mount and the truss mount remained attached to the firewall. A visual examination of the engine did not reveal any impact damage to the engine crankcase, cylinders, components, or accessories. The oil dipstick was intact and indicated an oil quantity of 8 qts when removed and examined. No evidence of fuel or oil leakage were observed. Propeller The three-blade Hartzell propeller had been removed from the crankshaft propeller flange. The blades remained captured in the hub and the spinner remained attached to the spinner bulkhead. The blades were marked with "A", "B", and "C" to assist with the examination. Blade "A" exhibited aft bending, curling of the blade tip, and abrasion on the trailing edge near the blade tip. Blade "B" exhibited curling of the blade tip and abrasion on the leading edge and cambered face near the blade tip. Blade "C" exhibited aft bending, curling of the blade tip, and abrasion on the leading edge, cambered face, and trailing edge. A two-blade, variable pitch propeller was installed to facilitate running the engine. On January 27, 2019, at 1514 central daylight time, a Piper PA-32RT-300T airplane, N39650, suffered a partial loss of engine power resulting in an off-field landing near Pfugerville, Texas. The pilot received minor injuries and the airplane was substantially damaged. The airplane was registered to Stew Industries, LLC, and was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Day visual meteorological conditions prevailed, and the flight was not operated on a flight plan. The flight originated from the Austin Executive Airport (EDC), Austin, Texas, with an intended destination of Taylor Municipal Airport (T74), Taylor, Texas. The pilot reported he started the day with 40 gallons of fuel onboard and confirmed a pilot logbook entry for 1.3 flight hours on the day of the accident. The 1.3 hours included flights flown from T74 to EDC and from EDC to Lakeway Airpark (3R9). The logbook did not include an entry for a subsequent flight from 3R9 to EDC or the accident flight. The pilot departed EDC to fly to T74 and had flown only a few miles when the engine started running rough. He stated he moved the fuel selector handle alternatively between the left and right fuel tank positions, turned on the fuel pump, and advanced the mixture to full rich, but the engine roughness continued. He tried to return to EDC, but could not make it. He performed an off-field landing to a road, where the airplane hit a parked car. The right wing separated from the fuselage during impact and the airplane flipped upside down. FlightAware captured the airplane's recorded flight track from 1355 to 1514 on the day of the accident. The data showed the airplane flying in the area between EDC and 3R9. The airplane was equipped with a J.P. Instruments, Inc.(JPI) engine data monitor (EDM) 700 configured to record individual cylinder head temperatures (CHT), cylinder exhaust gas temperatures (EGT), EGT span, and battery voltage. The unit was undamaged and National Transportation Safety Board (NTSB) investigators extracted data from the unit while it remained in the airplane wreckage. There were 5 distinct sessions on January 27, 2019, including the accident flight. The fourth session on the day of the accident recorded only 4 seconds of data and was not considered in the investigation. Ninety-four (94) minutes of data was recorded. Data associated with the accident flight showed a consistent decrease in CHTs during the final 3 minutes of flight. EGT data showed a series of decreases and increases in temperatures during the same period. (Figure 1) Figure 1 – Final Minutes of Accident Flight JPI Data Prior to the first engine run attempt the fuel line was disconnected from the main fuel servo at the engine and reconnected. No liquid/fuel was present in the fuel line. The fuel filter/screen was rem