Incident Overview
On August 10, 2014, at approximately 1020 Pacific daylight time, a Ryan Navion aircraft, registration N4533K, experienced a partial loss of engine power while on approach to land at Sierra Skypark Airport (E79) in Fresno, California. The airplane was registered to and operated by the pilot under 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan was filed. The flight had originated from Madera Municipal Airport (MAE) in Madera, California, at about 0950.
Flight Sequence
The pilot reported that the accident flight was the second flight of the day; the airplane had been operating normally with no indications of a potential malfunction. While approaching the destination airport to land, the pilot entered the traffic pattern for the runway. On short final, the pilot increased power to maintain the glideslope when he heard a "muffled bang or chug" followed by the engine sounding "as if it was drowning." The airplane began to descend, and the pilot executed an off-airport landing. During the landing sequence, the left wing impacted a fence. The airplane then traversed across a median before coming to rest against a second fence.
Postaccident Examination
A postaccident examination conducted by a Federal Aviation Administration Inspector revealed that the fuel system was intact and evidence of fuel was noted throughout. The spark plugs were removed and no damage was noted. The engine was rotated by hand and compression was evident on all six cylinders; the magneto impulse coupling also fired. The oil filter was removed and found to be clear of debris. The propeller blade tips were curled forward. At the conclusion of the engine examination, no preimpact mechanical malfunctions or failures were revealed that would have precluded normal operation.
Injuries and Damage
The pilot and two passengers were uninjured. The airplane sustained substantial damage to the left wing.