Accident Details
On June 5, 2014, at approximately 2130 Alaska daylight time, a tundra tire-equipped Aeronca 15AC Sedan airplane, registration N1301H, sustained substantial damage during an emergency landing at Dollar Creek Airstrip, near Talkeetna, Alaska. The airplane was operated by a certificated private pilot on a visual flight rules (VFR) cross-country personal flight under Title 14, CFR Part 91. The pilot was not injured. Visual meteorological conditions prevailed, and no flight plan was filed. The flight departed Lake Hood Airstrip, Anchorage, Alaska, about 2000, en route to Talkeetna via Pika Glacier.
According to the pilot, the purpose of the flight was to check on his son, who was camping on Pika Glacier as part of a mountaineering class. The pilot stated that he had exhausted the fuel from the left tank and was operating on the right tank with about 12 gallons remaining. After circling his son's camp twice at approximately 8,000 feet mean sea level, he departed for Talkeetna when the engine lost all power. Attempts to restore power by switching fuel tanks, applying carburetor heat, and pumping the throttle resulted in engine sputtering followed by a total loss of power. He turned toward Dollar Creek Airstrip, about 15 miles southeast at an elevation of about 800 feet, and managed to restore intermittent power by continuing to pump the throttle and rocking the wings. During the emergency landing, the engine sputtered, providing a short burst of power, causing the airplane to overshoot the intended landing area. The airplane overran the departure end of the runway and nosed over, sustaining substantial damage to the rudder and left wing lift strut.
Aircraft Information
The Aeronca 15AC Sedan was certificated under Civil Air Regulations (CAR) Part 03. The airplane's fuel tanks had been modified in accordance with an FAA Form 337 dated July 2, 1997, which allowed installation of two 24-gallon aluminum alloy fuel tanks replacing original bladder tanks. The modification specified that fuel management procedures remained unaltered except for quantities. However, no fuel flow tests, usable/unusable fuel quantity calculations, placarding, or flight manual supplements were referenced in the FAA Form 337. A FAA safety inspector from the Anchorage Flight Standards District Office approved the alteration.
Investigation Findings
Recovery personnel reported that the airplane came to rest inverted, with no visible fuel on the ground or vegetation. Approximately 8 gallons of aviation fuel were removed from the right fuel tank; no fuel remained in the left tank. Examination of the engine after recovery revealed no preaccident anomalies. The fuel system was examined: the vent system had been modified to an under-wing vent, and the original fuel selector (on/off only) had been modified to include options for both, left, or right tanks. The gascolator drain plug had been replaced with a brass plug; about three ounces of fuel recovered from the gascolator was light blue and appeared dirty, with rust-like particulate matter. The fuel screen strainer was dirty but not blocked. No obstructions were found in the fuel supply or vent systems.
Examination of the wing fuel tanks on June 21 revealed that the internal baffle in the left tank had half-moon lightening holes at the bottom, while the right tank's baffle lightening holes started about 1 inch from the bottom, and the baffle fit tightly against the tank bottom. Each tank was placarded "USABLE 24 GAL." on the exterior, while the cockpit fuel selector was placarded "36 GAL." No header tank was present. An FAA engineer estimated, based on measurements of an STC'd metal tank and extrapolation from the FAA Form 337, that total fuel per tank was about 22.5 gallons, with unusable fuel estimated at 4 to 5 gallons per tank.
Weather information from Talkeetna Airport, about 30 miles east, reported at 2153: wind from 210 degrees at 5 knots, visibility 10 statute miles, clear sky, temperature 59°F, dew point 36°F, altimeter 30.04 inHg.