Luscombe 8 N71899 accident near Bend, Oregon

Probable cause

A failure of the left fuel valve, which resulted in fuel exhaustion and a total loss of engine power.

NTSB analysis

The pilot reported that he departed with full fuel tanks, which should have provided about 3.5 hours of endurance. While enroute, the pilot noted the fuel levels in the two fuel tanks were uneven and were draining faster than expected and that the left fuel gauge appeared lower than the right gauge. The pilot had difficulty monitoring the airplane’s fuel levels because he perceived the fuel gauges to be inaccurate and the needles were bouncing. As the airplane approached the destination airport at the conclusion of the 2.5 hour flight, the engine suffered a total loss of power. The pilot performed a forced landing in a field, during which the airplane impacted a fence and came to rest inverted. As a result, the airplane sustained substantial damage to the fuselage and empennage.

Postaccident photos revealed the lower cabin insulation was fuel soaked, and fuel staining was observed beneath the left fuel valve. The pilot reported that both fuel tanks were devoid of fuel after he impacted the ground. When fuel was fed into the airplane’s left fuel line after the accident, the left fuel valve began to leak from around the valve shaft.

Figure 1: The left fuel valve and fuel system diagram.

Based on the available information it is likely that the airplane lost an unknown quantity of fuel due to a leak in the left fuel valve, which resulted in fuel exhaustion and a total loss of engine power.

Text from the NTSB. Open the NTSB docket for WPR24LA294 for the full record.