Accident Sequence
On June 11, 2022, at about 1836 Pacific standard time, a Piper PA-24-250, registration N7428P, was substantially damaged during a forced landing near Auburn, Washington. The pilot and passenger were not injured. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
The total flight duration was about 1 hour. Approximately 18 nautical miles from the destination airport, the pilot moved the fuel selector from the left main fuel tank to the right main fuel tank. About 5 miles from the airport, he completed the before-landing checklist and reduced engine power to 15 inches of manifold pressure while slowly advancing the propeller lever. Shortly thereafter, the engine lost total power. The pilot immediately verified that the mixture was full rich and the fuel boost pump was on. He then moved the fuel selector back to the left main tank, but quickly switched again to the right main tank because it contained more fuel. The engine briefly restarted but lost power again. The pilot executed a forced landing to an open field. During the landing roll, the airplane struck a dirt berm, resulting in substantial damage to the right wing.
After the accident, the pilot powered the aircraft, selected the right main tank, and turned on the electric fuel pump. He initially heard the pump cavitate but then observed the fuel pressure gauge rise. He then turned off the power and placed the fuel selector back to the off position. His visual inspection showed no fuel in the left main tank, while the right main tank contained "plenty of fuel."
Postaccident Examination
A postaccident examination of the airframe and engine found no preimpact mechanical anomalies. The right main tank, right auxiliary tank, and left auxiliary tank appeared full of fuel. The left main tank was not breached and contained about one gallon of fuel. The fuel system was traced from each wing tank to the carburetor through the fuel selector, which rotated normally and was unobstructed. The fuel selector was in the off detent when first viewed. All four selector positions (right and left main, left and right auxiliary) produced audible and tactile detents. With the selector positioned to each tank, fuel escaped from the fuel strainer/drain. The fuel supply and vent lines in both wing tanks were free of obstructions. The carburetor was disassembled; the bowl contained about 5 ounces of fuel, and the metal floats were intact. No water was detected in the carburetor bowl using water-finding paste. The accelerator pump functioned when the throttle was actuated, and the needle valve and seat functioned when the float was moved manually.
Mechanical continuity of the engine rotating group, valvetrain, and accessory section was confirmed when the crankshaft was manually rotated. Thumb compression was achieved on all six cylinders, and valve lift appeared normal. A lighted borescope inspection of the cylinders revealed normal piston face and valve signatures, with no signs of catastrophic engine failure.
Weather Conditions
Weather observations at Seattle-Tacoma International Airport (SEA), about 43 minutes before and 17 minutes after the accident, reported a temperature of 20°C and dew point of 9°C. A review of the carburetor icing probability chart from FAA SAIB CE-09-35 indicated that these conditions were favorable for serious icing at glide power.