Beech 58 — Kerrville, TX

What happened

The pilot was conducting an instrument flight rules (IFR) flight in a twin-engine airplane with five passengers. During a GPS approach to the destination airport, both engines lost total power within 10 seconds of each other; the left engine regained near full power about 40 seconds later, which it maintained until the end of recorded data. As the pilot continued the approach, he did not ensure the flaps were up or feather the propeller of the inoperative right engine, which was contrary to the airplane manufacturer's emergency procedures guidance.

As the airplane descended with the right engine inoperative below the cloud ceiling to about 500 ft agl, its flightpath leveled and airspeed decreased below the minimum controllable airspeed (Vmc). The airplane's continued flight profile below Vmc with the unfeathered propeller of the inoperative right engine, the left engine near full power, and the airplane's aft center of gravity resulted in a right-turning spin and ground impact.

The pilot's filed flight plan indicated a minimum fuel load required of 58 gallons, although this did not account for the instrument approach and alternate airports. However, the pilot's flight planning log indicated only 50 or 54 gallons of fuel onboard. Thus, based solely on the pilot's logs, there was insufficient fuel onboard the airplane to embark on the flight. Because the airplane was beyond its maximum gross weight with just 50 gallons of fuel onboard, it is likely that the pilot did not want to add additional fuel. Thus, the pilot's decision to depart on the accident flight without adequate fuel onboard showed poor judgement.

Although the pilot departed without an adequate fuel reserve for the IFR flight, an actual fuel load of 50 or 54 gallons would have been sufficient to reach the destination airport (the airplane burned about 42 gallons just before the crash site about 6 miles from the airport). However, when the airplane was fueled at the pilot's request 8 days (five flights) before the accident flight, it was not completely filled. Because the pilot was not present for the fueling and did not crosscheck the fuel receipt with his fuel-planning logs, he did not recognize that the error meant he had less than 50 gallons of fuel onboard before departing on the accident flight. As evidenced by the close correlation between the pilot's fuel logs and the engine data monitoring (EDM) fuel consumption data for the accident flight and the five flights before it, the pilot mainly relied on EDM data to determine the quantity of fuel onboard the airplane. Thus, the fueling error introduced 8 days before the accident was carried through the pilot's planning logs for the next six flights, including the accident flight.

Further review of the accident airplane's fueling records, the pilot's flight-planning logs, and fuel consumption data from the EDM revealed that the airplane actually had about 12 gallons less fuel than the pilot indicated in his fuel log for the accident flight. Thus, the lack of sufficient fuel for the accident flight resulted in the airplane's engine power loss during the approach.

In addition, the abnormally high resistances in both fuel quantity transmitters would have caused the cockpit fuel quantity indicators for both wings to read about 5 gallons higher each than the actual fuel present, corresponding to an additional 1/16th tank on each of the indicators. Thus, because of the high resistances in both fuel quantity transmitters, the pilot's belief that 50 (or 54) gallons of fuel were onboard at takeoff (rather than the actual fuel level of 38 gallons) may have been corroborated by the fuel quantity indicators; however, the effect of the inaccurate indications on the pilot's actions are uncertain.

The pilot's autopsy indicated he had severe coronary artery disease, which placed him at increased risk of a sudden cardiac event. However, the accident sequence was not consistent with acute pilot impairment or incapacitation as recorded data indicate that the pilot was controlling the airplane up until the airplane dropped below its minimum controllable airspeed, so it is unlikely that the pilot's coronary artery disease or any sudden medical event contributed to this accident.

In summary, multiple errors before takeoff led to a loss of engine power due to fuel exhaustion. The pilot did not accurately record the amount of fuel added after fueling, the pilot did not verify the amount of fuel onboard the airplane, the fuel quantity transmitters did not accurately indicate the amount of fuel onboard, and the pilot decided to take off with inadequate fuel to conduct the IFR flight in an overweight airplane. Lastly, during the flight, once the right engine lost power, the pilot failed to properly configure the airplane per the manufacturer's emergency procedures guidance and allowed the airspeed to drop below the point at which the airplane could maintain flight.

An editorial "what led to it / how to avoid it" analysis for this accident is generated separately and will appear here.