Event Summary
While operating VFR-on-top for approximately 10 minutes, the aircraft's engine began producing a severe vibration and partial power was lost. The pilot declared an emergency and received weather conditions and a heading to the Industrial Air Park (ADM) in Ardmore, Texas, from Flight Service. The pilot then contacted Fort Worth Center and initiated an IFR descent through the clouds.
Descent and Landing
Upon exiting the clouds at about 400 feet above ground level, the aircraft was unable to maintain altitude. During the continued descent, it struck electrical wires and made a crash landing into a small mowed pasture. The airplane rolled approximately 300 feet before entering a vast depression, passed through a persimmon thicket, and came to rest inverted.
Damage Examination
An examination of the aircraft revealed damage to the left wing spar and left horizontal stabilizer. Additionally, a cylinder head had separated from the barrel.