Beech A36 N104RK accident near Lago Vista, Texas

Probable cause

The pilot’s mismanagement of the fuel system which resulted in fuel starvation and a total loss of engine power. Contributing to the accident was the pilot’s failure to maintain airspeed which resulted in the airplane exceeding its critical angle of attack and an aerodynamic stall at a low altitude.

NTSB analysis

The pilot was conducting a personal cross-country flight when there was a loss of engine power while in the traffic pattern at the destination airport. The pilot’s attempts to restore engine power, including switching fuel tanks, were unsuccessful. The pilot heard the airplane’s stall warning horn shortly before the airplane rolled right and entered an aerodynamic stall at a low altitude. The airplane impacted vegetation and terrain in a nose low attitude. The airplane came to rest inverted, with the fuselage suspended above the ground, against vegetation. The airplane sustained substantial damage to both wings and the fuselage.

The pilot did not directly ascertain how many gallons of fuel were in the main fuel tanks before departure. The wingtip auxiliary fuel tanks were empty at departure. The pilot estimated that the flight departed with about 56 gallons of fuel available; however, based on available information, the investigation could not determine with an appreciable level of accuracy how many gallons of fuel was available before the flight and how it was distributed between the two 40-gallon (37 gallon usable) main fuel tanks.

The pilot stated that the flight departed with the fuel selector positioned on the left main fuel tank where it remained until the airplane lost engine power while in the traffic pattern at the destination airport. According to track data, about 2 hours of flight time had elapsed when the accident occurred. The pilot repositioned the fuel selector valve to the right main fuel tank after the loss of engine power, but that action did not restore engine power.

Postaccident examination revealed that the fuel selector valve was positioned to use fuel from the right main fuel tank. First responders to the accident site reported that there was fuel leaking from the damaged right wing. There was no evidence of fuel in the left main tank or the auxiliary wingtip fuel tanks. Additionally, there was no evidence of fuel in the lines connected at the fuel selector valve, in the fuel lines forward of the firewall, fuel strainer assembly, engine-driven fuel pump, fuel manifold valve, or the fuel injector lines. About ½ tablespoon of fuel was recovered from the fuel metering assembly. A disassembly of the engine-driven fuel pump confirmed the drive coupler remained intact. A postaccident engine examination did not reveal a mechanical failure that would have prevented normal operation; the loss of engine power was likely due to an interruption of fuel flow to the engine.

Based on available performance data for the cruise altitudes flown during the flight, the expected fuel consumption rate at 75% engine power is 13.5-15.2 gallons per hour (gph). However, the airplane was not equipped with an engine monitor or fuel flow meter with the ability to record how the engine was operated during the flight and, as such, the amount of fuel used during the flight could not be calculated with an appreciable level of accuracy.

Based on the available evidence, if the pilot switched to the fullest main fuel tank before landing, as required by the airplane’s Before Landing Checklist, there likely would have been sufficient fuel remaining to safely land at the destination airport. The loss of engine power was likely due to fuel starvation resulting from the pilot’s mismanagement of the fuel system.

Text from the NTSB. Open the NTSB docket for CEN20LA421 for the full record.