Accident Overview
On June 25, 2017, about 1400 central daylight time, a Bellanca 17-30A airplane, registration N14728, was substantially damaged during a forced landing to a field approximately half a mile south of Grove Municipal Airport (KGMJ), Grove, Oklahoma. The private pilot and passenger were not injured. The personal flight was conducted under Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no Federal Aviation Administration flight plan had been filed. The flight had departed Bollinger-Crass Memorial Airport (MO5), Van Buren, Missouri, about 1230, and was en route to KGMJ.
Pilot's Account
According to a written statement submitted by the pilot, while en route at an altitude of 8,500 ft mean sea level, he leaned the fuel mixture and the engine started running rough with a partial loss of power and a "miss-fire." The pilot enrichened the fuel mixture and switched fuel tanks, after which the rough-running engine cleared up. The flight continued without incident until the pilot was maneuvering for landing. While in a right turn from the base leg to the final leg, the engine lost partial power. The pilot switched from the right fuel tank to the auxiliary fuel tank but was unable to restore all engine power.
Post-Accident Examination
An FAA inspector who responded reported that both the left and right wing spars were substantially damaged during the forced landing. A post-accident examination of the fuel tanks revealed 5.75 gallons of fuel in the right fuel tank and 15 gallons (full) in the auxiliary fuel tank. Visible fuel was present in the left tank, but it was not measured.
The airplane was recovered for further examination and testing. An airframe and powerplant mechanic assisting with the investigation drained 5 gallons from the right tank, 5 gallons from the left tank, and noted the auxiliary tank was full. There was no evidence of fuel leaks around either fuel cap, and the fuel screens were free of contamination.
Additional fuel was added to the tanks, and the engine started without hesitation, running for 25 minutes at varying power settings. After the engine warmed to normal operating temperatures, the mechanic cycled through all three fuel tanks, spending at least 5 minutes on each. Checks of both magnetos and the mixture control revealed no anomalies. The loss of engine power and engine roughness could not be duplicated.
Fuel System Information
The airplane was equipped with a 34-gallon left main fuel tank, a 34-gallon right main fuel tank, and a 15-gallon auxiliary tank. According to placards on the fuel filler caps and the Pilot Operating Handbook, 4 gallons on each side were unusable.