Beech F33A N1HH accident near Williams, Arizona

Probable cause

The pilot’s activation of the auxiliary fuel boost pump shortly after takeoff, which resulted in an excess amount of fuel to the engine and a total loss of engine power.

NTSB analysis

The pilot reported that, during previous flights, he had observed overheating of two of the engine cylinders, and activation of the auxiliary fuel boost pump had worked to resolve the overheating. Shortly after takeoff on the accident flight, the pilot observed cylinder heating and activated the boost pump, after which the engine lost total power. The pilot performed a forced landing in an open desert field. The airplane landed hard and impacted vegetation during the landing roll, resulting in substantial damage to the airplane.

Data retrieved from the airplane’s engine monitoring system showed that the fuel flow rate increased from 23.4 gallons per hour (gph) to 28.7 gph, with a peak fuel flow of 30.8 gph, followed by a sudden decrease. The engine manufacturer recommended that the fuel flow setting should be between 23.2 – 24.9 gph. Both the pilot operating handbook for the airplane and a placard on the auxiliary boost pump indicated that the pump should be off during takeoff and only turned on in the event of a loss of fuel pressure.

It is likely that the pilot’s activation of the auxiliary fuel boost pump resulted in excess fuel being delivered to the engine during the initial climb, which resulted in the total loss of engine power.

A postaccident examination of the airframe and engine revealed no evidence of mechanical failures or malfunctions that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR22LA083 for the full record.