North American AT 6C accident near Buckley, Washington, June 4, 2014

The NTSB's narrative final · quoted from the NTSB record

The two airline transport pilots, one of whom had recently purchased the airplane from the other, departed for the local personal flight to familiarize the new owner, who was seated in the front seat, with the airplane. The airplane was equipped with dual flight controls; however, it could not be determined which pilot was manipulating the controls at the time of the accident. Review of a video provided by a witness showed the airplane take off, and the engine sounded normal. A witness reported that, shortly after the airplane passed the departure end of the runway, the engine began to "sputter." The airplane then initiated a right turn. Throughout the turn, the engine seemed to power up but then lose power shortly thereafter several times. As the airplane completed the turn to a heading toward the departure airport, the engine lost total power. The airplane then descended into trees. Postaccident examination of the airplane revealed that the right wing fuel line was connected to the fuel selector valve outlet port and that the engine fuel supply line was connected to the right fuel tank position of the fuel selector valve. The fuel selector valve was removed, disassembled, and found in the left tank position, slightly away from the detent; however, it could not be determined if the fuel selector valve was moved during the impact sequence. With the right wing fuel tank line and the engine supply fuel line installed as found and with the fuel selector valve positioned to either the left main or left reserve fuel tank positions, fuel could not flow from the left fuel tank to the engine, which would have resulted in a loss of engine power; however, fuel could flow from the left to the right fuel tank. If the selector valve was positioned to the right fuel tank position, fuel could flow to the engine. Examination of the fuel tanks at the accident site revealed that the left fuel tank contained fuel to a level that corresponded to the location of where the fuel tank was breached, and no fuel was observed within the right fuel tank. Based on the available evidence, it could not be determined if the incorrect installation of the selector valve fuel lines prevented fuel flow to the engine and the loss of engine power. The fuel selector valve position at the time of the accident could not be determined because it is possible that the valve moved during the impact sequence. Examination of the carburetor revealed that one of the carburetor floats was partially filled with liquid and that the other float was impact-damaged and separated from the carburetor; it could not be determined if the floats were filled with liquid before the accident. Although a float filled with liquid would allow the fuel flow into the carburetor float bowl to increase and one partially filled float would result in a slightly rich condition, if a rich fuel to air mixture had existed, additional signatures would have been present within the engine exhaust and spark plugs, all of which exhibited normal operating signatures. No additional anomalies were found that would have precluded normal operation of the engine. Autopsy and toxicology findings for the front seat pilot revealed that his heart was heavier than average, likely due to the effects of high blood pressure. However, it is unlikely that this condition or the medications that he was taking to treat it contributed to the accident. Autopsy and toxicology findings for the aft seat pilot revealed that he had significant coronary artery disease with up to 80 percent occlusion of the left anterior descending coronary artery, which would have increased his risk of impairment due to sudden onset symptoms, such as chest pain or irregular heart rhythms. However, the investigation was unable to determine if the aft seat pilot was having any such symptoms at or around the time of the accident. In addition, the aft seat pilot had been using sertraline to treat depression for 2 months before the accident, but the investigation was unable to determine the full extent of the pilot's depression or side effects from the medication. Although the aft seat pilot had coronary artery disease and depression, it is unlikely that these conditions contributed to the accident.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

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