Accident Overview
On June 8, 2023, at about 1219 mountain daylight time, a Piper PA-30, registration N7318Y, was substantially damaged during a forced landing near Nephi, Utah. The pilot, who was the sole occupant, was not injured. The airplane was being operated as a Title 14 Code of Federal Regulations Part 91 personal flight.
Engine Power Loss
The pilot reported departing from Cedar City Regional Airport (CDC) in Cedar City, Utah, with the intention of relocating the airplane to Skypark Airport (BTF) in Bountiful, Utah, for an annual inspection. While cruising at approximately 9,500 ft mean sea level, the left engine's rpm decreased from 2,400 to 1,000 rpm briefly before returning to 2,400 rpm. Subsequently, the engine continued to cycle sporadically between 1,000 and 2,400 rpm. The pilot attempted to troubleshoot the issue but decided to divert to Nephi Regional Airport (U14) in Nephi, Utah, and initiated a straight-in approach to runway 17.
Landing and Impact
During the landing flare, about 5 ft above the runway, the left engine lost all power. The pilot immediately applied right rudder to counteract the lowered left wing; however, the airplane touched down and exited the left side of the runway. The airplane subsequently impacted a dirt mound and came to rest in an open field. The right wing sustained substantial damage.
Postaccident Examination
Postaccident examination of the airframe and both engines did not reveal any preimpact mechanical anomalies. The fuel system was traced from each wing tank to the carburetor through the fuel selector, which rotated normally and was unobstructed. Fuel lines that were not damaged or removed for transport were secure. Fuel sampled from the right strainer was tested with water-finding paste and revealed no water contamination.
Removal of both the left and right fuel strainer bowls and filter discs revealed contaminants consistent with rust/corrosion. Corrosion was found in the cavity walls and cover plate of both fuel strainer knob assemblies. The left and right fuel selector valves were removed, and corrosion was found in the threads of the left and right fuel line auxiliary outlet unions. A follow-up examination of the fuel flow dividers and fuel servos did not reveal any mechanical anomalies or failures.
Mechanical continuity was established throughout the rotating group, valvetrain, and accessory section as the crankshaft was manually rotated. Thumb compression was achieved at all four cylinders, and the valves displayed normal lift. Borescope examination of the cylinders' combustion chamber interior components revealed normal piston face and valve signatures, with no indications of catastrophic engine failure.
Previous Maintenance
The pilot stated that about 7 months prior to the accident flight, the right engine fuel injectors were found obstructed during an inspection. According to the engine logbooks, on February 2, 2023, approximately four months before the accident, the right engine experienced a loss of power in flight. Troubleshooting found a restricted fuel screen and corrosion. The mechanic replaced both fuel screens and gaskets, replaced the right outboard auxiliary tank fuel line, flushed the fuel lines, and cleaned all fuel nozzles. The left engine's fuel nozzles were also cleaned and the fuel lines flushed during that maintenance event.