Pilots Can Learn From NTSB Final Report on Bonanza Accident in Arizona

According to the NTSB report, the accident aircraft, a 1975 Beechcraft F33A Bonanza, departed H. A. Clark Memorial Field Airport (KCMR) in Williams, Arizona, on January 26, 2022, at about 10:55 a.m. MST. The pilot had planned to fly to Eagle Airpark (A09) in Bullhead City, Arizona.

The pilot reported to NTSB investigators that following departure, as the aircraft climbed through about 700 to 800 feet agl, the engine lost power and he initially attempted to turn back toward the airport. The pilot said the stall warning sounded as he began the turn, and it quickly became clear the aircraft could not glide back to the airport, so he opted to land in a field. The Bonanza “subsequently landed hard and impacted vegetation during the landing roll,” the NTSB report stated. The aircraft was substantially damaged, and the pilot sustained minor injuries.

During interviews with the NTSB, the pilot said that during previous flights he had noticed “minor heating” in two of the engine’s cylinders, which he mentioned to his mechanic. His mechanic reportedly told him to turn on the fuel boost pump to resolve the problem. According to the report, the pilot said this technique “worked great until the day of the accident.”

During the accident flight, the pilot noticed the two cylinders overheating while climbing shortly after takeoff and turned on the boost pump. The engine lost power immediately afterward.

The mechanic told investigators that he suggested the pilot take note of exhaust gas temperature, cylinder head temperature, and fuel flow when the problem occurred, and bring in the accident airplane for further maintenance.

“He did not recall suggesting that the pilot use the auxiliary fuel boost pump during takeoff or climb,” the report stated.

The NTSB said the probable cause of the accident was “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.”

While some details of the pilot and mechanic’s recollection of circumstances leading up to the accident do not align, the event presents an example of how easily pilots can make mistakes when they do not follow the manufacturer’s instructions that accompany the aircraft.

Both the POH for the F33A and a placard near the auxiliary boost pump indicate the pump should be off during takeoff and turned on only during a loss of fuel pressure. Fuel pump procedures can differ significantly between aircraft, depending on the engine and fuel system. Some aircraft use auxiliary pumps for priming and little else short of an emergency.

The Continental IO-520 BA in the F33A contrasts with the Lycoming IO-540 in my airplane, which operates with the boost pump on during takeoff and landing. Such differences can be tricky for pilots who fly many different aircraft types or those who recently began flying new airplanes with fuel systems that differ from their old ones.

As is often the case with aviation accidents, the case of this F33A reflects the need for pilots to stay intimately familiar with their aircrafts’ operating manuals, systems and placarding, and to maintain a high level of formality and care when reviewing checklists before, during, and after flights.