Amateur-built RV-7 N331KM accident near Nevada City, California

Probable cause

The improper installation of the fuel pump, leading to a fatigue failure of the pump's lever arm and subsequent loss of engine power. Contributing to the accident was the lack of suitable terrain for a forced landing.

NTSB analysis

The pilot of the two-seat experimental airplane transmitted a distress call stating that he had lost engine power and could not restart the engine. Another pilot who was airborne at 5,500 feet msl (mean sea level) at the time of the accident said that he had radio communications with the pilot of the accident airplane. The accident pilot stated that he could not get the engine to restart, that he had tried everything, and he was going down. The pilot then observed the accident airplane in a controlled descent into an area populated by large trees. A postaccident examination of the engine revealed that the lever arm of the engine-driven fuel pump had failed in fatigue. Testing of the electric fuel boost pump demonstrated that it was capable of delivering fuel to the engine; however, the Pilot's Handbook of Aeronautical Knowledge states that, in regard to fuel-injected engines, it is difficult to restart a hot engine or an engine that quits because of fuel starvation. The airplane logbooks documented that 44 days earlier the engine-driven fuel pump had been removed and replaced twice. After the first installation the engine would not run. The fuel pump was installed a second time, which resulted in successful engine operation. The engine ran for 16.1-hours before the fuel pump lever arm failed from a fatigue crack in the pivot area of the arm, causing the engine to lose power from fuel starvation. It is possible to incorrectly install this type of fuel pump. When the engine's fuel pump push rod is in the extended position it can interfere with the placement of the fuel pump lever arm during the installation, which results in it being obstructed or jammed against the engine case, possibly creating a crack in the pivot area of the lever arm. In this situation the engine usually does not run because the pump lever arm and engine push rod are not aligned correctly and fuel is not being pumped. The crack may not be visually detectable because the location is obscured by the pump case.

Text from the NTSB. Open the NTSB docket for LAX08LA063 for the full record.