Piper PA-30 N7318Y accident near Nephi, Utah

Probable cause

A total loss of engine power due to fuel contamination as a result of the inadequate removal of fuel system corrosion during previous maintenance.

NTSB analysis

The pilot was conducting a repositioning flight when, while enroute, the left engine briefly lost power. The pilot attempted to troubleshoot, but the engine continued to cycle between 1,000 and 2,400 rpm. The pilot diverted to a nearby airport for a precautionary landing. During the landing flare, about 5 ft above the ground (agl), the left engine lost total power. The pilot applied right rudder to counteract the lowered left wing; however, the airplane touched down hard and exited the left side of the runway. The right wing impacted a dirt mound and sustained substantial damage.

Postaccident examination of the fuel system, left and right fuel strainer bowls, and filter discs revealed that the filter bowl and filter disc contained contaminants consistent with rust/corrosion. Both the left and right fuel strainer post had pitting corrosion. Rust/corrosion was also found in the cavity walls and cover plates of both strainer knob assemblies, as well as in the left and right fuel selector valves, primarily the left and right auxiliary inlet lines.

Review of the airplane’s maintenance records revealed that, about four months before the accident flight, the right engine lost power in flight; after that event, the fuel screen was found restricted and corroded. The pilot stated that multiple injectors from both engines were also found obstructed. The right outboard auxiliary tank was replaced, along with the fuel screens. Both left and right fuel lines were flushed by a mechanic. The pilot added about 7 months prior to the accident flight, the right engine fuel injectors were found obstructed during an inspection.

The rust/contamination found months before the accident was likely not adequately addressed and not completely removed from within the fuel system, which led to a build-up of contamination within the fuel delivery system that restricted the fuel supply to the left engine and resulted in the loss of power.

Text from the NTSB. Open the NTSB docket for WPR23LA220 for the full record.