Beech A36 N2270L accident near Houghton Lake, Michigan

Probable cause

A loss of engine power during cruise flight for undetermined reasons.

NTSB analysis

The accident occurred during a two-leg cross-country flight. The airplane was fully fueled before the return flight. After takeoff, the flight climbed to about 9,000 ft above mean sea level (msl) and proceeded direct to the intended destination. Midway through the flight, the engine began “sputtering for a quick second” and subsequently lost power. The pilot’s attempts to restore engine power, which included adjusting the mixture, were not successful. The propeller continued to windmill during the gliding descent. The pilot executed a forced landing to an open marsh area, and the fuselage and both wings were damaged during the impact sequence.

Postaccident examinations of the fuel-injected engine and airframe fuel system did not reveal any anomalies consistent with a loss of engine power. The left-wing fuel tank vent was clogged with dirt due to the ground impact. The left-wing fuel vent orifice within the fuel tank bladder contained a small amount of debris; however, the vent was not fully obstructed and remained operational. The right-wing fuel vents were clear. Fuel was recovered from both wing tanks at the accident site.

Engine monitor data revealed that the oil pressure, fuel flow, and exhaust gas and cylinder head temperatures were stable during the initial portion of the flight. However, at the time of the loss of engine power, the fuel flow abruptly dropped to near zero and remained there for the duration of the flight. Engine speed and manifold pressure data was not recorded. The exhaust gas temperatures initially increased and then decreased abruptly.

The data recovered from the engine monitor suggested that the loss of engine power was due to an abrupt decrease in fuel flow. However, the engine and airframe fuel system examinations did not reveal any discrepancies consistent with a loss of fuel flow, specifically, or a loss of engine power, in general. The amount of fuel drained from the airplane following the accident indicated that fuel was present in both fuel tanks at the time of the power loss. The minor debris observed in the right fuel tank vent was not significant enough to obstruct the vent line and did not contribute to the loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN22LA403 for the full record.