Blountville

The airplane was flying in instrument meteorological conditions at flight level 200 (about 20,000 feet), and a large area of thunderstorm activity was located to the northwest. About 20 miles from the thunderstorm activity, the airplane began to encounter moderate turbulence and severe icing conditions. The pilot deviated to the south; however, the turbulence increased, and the airplane entered an uncommanded left roll and dive. The autopilot disengaged, and the pilot's attitude indicator dropped. The pilot leveled the airplane at an altitude of 8,000 feet and landed without further incident. Subsequent examination revealed that one-third of the outboard left elevator separated in flight and that the empennage was substantially damaged. Meteorological and radar data revealed the airplane entered an area of rapidly intensifying convective activity, which developed along the airplane's flight path, and likely encountered convectively-induced turbulence with a high probability of significant icing. The effect of icing conditions on the initiation of the upset could not be determined; however, airframe structural icing adversely affects an airplane's performance and can result in a loss of control.

The pilot reported that as he overflew the Tri-City airport, Tennessee at 9,000 feet, the right engine power slowly decreased. The airplane was in the clouds with an outside air temperature of about zero degrees Celsius. Right engine manifold heat was applied for a few seconds, with no noticeable difference in engine performance. The right magnetos were also checked with no obvious malfunctions noted. A descent for landing was initiated to the Tri-City airport and manifold heat was applied and removed several times, with no appreciable effect. On short final approach, when the landing gear was extended, the right main gear did not indicate down. There was insufficient time to perform the emergency gear extension procedure. A go-around was initiated, during which the pilot discovered that the left manifold heat control was now stuck in the 'ON' position. The pilot stated that with less than full power available on the left engine, and the right propeller unfeathered, the airplane could be climbed to about 200 feet. He flew the airplane until terrain clearance was no longer possible, then landed in a field, gear up. The airplane slid into trees and was substantially damaged.