ERA25LA007

About 36 minutes after departure and while on final approach to land, the pilot heard a loud “pop” and felt heat emanating from an area behind the pilot and copilot’s seats. As the airplane approached the runway threshold, smoke accumulated in the cabin and visible flame developed. During the landing, the airplane’s nose landing gear collapsed, and the airplane came to rest on the runway. The in-flight and postaccident fire consumed a majority of the airplane. Postaccident examination revealed that the fuel selector was positioned to the auxiliary fuel tank. The right main fuel tank’s vent line was found attached, but its two hose clamps were not secured. A loose B nut was also observed on a high pressure hydraulic hose located at the controllable relief valve in the engine compartment. The majority of the fuel supply, vapor return, and vent lines were destroyed by fire. According to the airplane flight and service manuals, when the main tanks were full, use of the auxiliary fuel tank could result in vapor return fuel being expelled overboard through the main tank vent system until at least 1 hour of flight had been completed or 10 gallons of fuel had been consumed. A preaccident photograph showed the vent outlet located approximately 10 inches aft of, and generally aligned with, the left exhaust extension. The pilot reported departing with the fuel selector positioned to the auxiliary fuel tank and making no subsequent changes. Although overboard fuel expulsion from the main fuel tank vent line was the most likely source of fuel for the fire, hydraulic fluid from the loose B-nut could not be ruled out. Thermal exposure and wreckage movement likely contributed to the loose hydraulic fitting, making it a less likely fuel source; however, due to thermal damage the source of the fire could not be determined with confidence.

On October 03, 2024, about 1730 eastern daylight time, a North American Navion airplane, N9117R, was substantially damaged when it was involved in an accident at Rutherford County Airport / Marchman Field (FQD), Rutherfordton, North Carolina. The pilot and passenger sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he departed Concord-Padgett Regional Airport (JQF), Concord, North Carolina, and was destined for FQD. About 36 minutes into the flight and while on final approach to runway 19 at FQD, the pilot heard a loud “pop” and felt heat coming from behind the pilot and copilot’s seats. As the airplane approached the runway threshold, the cabin filled with smoke and fire was visible in the cabin. During the landing, the airplane’s nose landing gear collapsed and the airplane came to rest on the runway. The in-flight and postaccident fire consumed a majority of the airplane. A witness captured video of the airplane as it approached the runway that showed fluctuating flames along the lower fuselage. Postaccident examination showed that most of the fuel supply, vapor return, and vent lines were destroyed by fire. The fuel selector valve was observed in the auxiliary fuel tank position. The gascolator assembly was not located among the recovered wreckage. The main fuel tanks exhibited thermal expansion; the right tank displayed a breach along its inboard seam. The right fuel tank’s flexible vent hose remained attached, but its two hose clamps were unsecured. Hydraulic components in the engine area exhibited thermal damage, and a loose B-nut was observed on a high-pressure hydraulic hose attached to the controllable relief valve. Service publications indicated that the main fuel tank vent line extended into the atmosphere beneath the left side of the fuselage near the wing’s leading edge. A caution note in both the service and flight manuals advised against operating the airplane from the auxiliary fuel tank until the airplane has flown at least an hour or used a minimum of 10 gallons of fuel. The caution adds that use of auxiliary tank fuel, when the main tanks are full, will result in vapor return fuel flowing overboard through the vent lines, as this fluid normally flows into the main tanks. A preaccident photograph of the airplane showed the vent outlet located about 10 inches aft of, and generally aligned with, the left exhaust extension pipe. The pilot reported that he departed with the fuel selector on the auxiliary fuel tank and did not change positions during the flight.