MIA99LA152

After performing several aerobatic maneuvers at about 6,000 feet msl and 110 mph, the pilot noted that the engine rpm surged for about two seconds and then recovered to the previously set 2,500 rpm. He elected to return to the departure airport, which was about 17 miles from his location. About 1 minute later, at an altitude of 5,500 feet he said he '...noted the oil temperature started to climb.' At this point he was about 14 mile from the airport. He said, '...the engine vibrated severely with a loud metallic sound, oil poured onto the windscreen, and the cockpit filled with smoke...and the engine simultaneously seized, stopping the prop before I could feather it...I...determined that we could probably not clear the ridge line...the only practical place within gliding range to perform a forced landing was a small pasture about 1 mile behind us in the bottom of a valley alongside a small road...slowing to...90 mph...touched down about 150 feet past the fence...I had difficulty keeping the tailwheel from bouncing as we plowed through the high grass and had to make continuos rudder inputs to keep tracking straight. After approximately 300 feet of roll out, the aircraft yawed right, the left main collapsed under the aircraft, and we slid sideways onto the bottom left wing, which snapped off, taking the left upper wing with it...rotated about 180 degrees counterclockwise, and stopped in an upright position....' The engine teardown revealed that the No. 6 connecting rod had failed due to oil starvation. According to the FAA inspector, the cause of the oil starvation was 'undetermined.'

On May 8, 1999, about 1010 eastern daylight time, a Christen Pitts S-2B, N260Z, registered to a private individual, impacted with the terrain near Knoxville, Tennessee. Visual meteorological conditions prevailed at the time, and no flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was substantially damaged. The commercial-rated pilot and one passenger reported no injuries. The flight had originated at 0950, from the McGhee Tyson Airport, Knoxville.

According to the pilot after performing several aerobatic maneuvers and, "...then performed a basic snap roll, entering the maneuver at about 6,000 feet msl at 110 mph...while completing the maneuver, the engine rpm surged for about two seconds and then recovered to the previously set 2,500 rpm...I scanned the engine instruments and noted the oil pressure to be at the bottom of the arc, with all other indications normal." He elected to return to the departure airport, which was about 17 miles from his location.

About 1 minute after turning to the airport, at an altitude of 5,500 feet he said he "...noted the oil temperature started to climb." He notified approach control that he was having "a potential engine oil system problem" and stated his intentions to enter a left base for runway 23. At this point he was about 14 mile from the airport.

He said, "...immediately after this radio transmission, the engine vibrated severely with a loud metallic sound, oil poured onto the windscreen, and the cockpit filled with smoke. I immediately pulled the mixture control to idle cutoff, and the engine simultaneously seized, stopping the prop before I could feather it. We were at approximately 5,500 feet msl. I announced the engine failure to Knoxville approach and determined that we could probably not clear the ridge line...the only practical place within gliding range to perform a forced landing was a small pasture about 1 mile behind us in the bottom of a valley alongside a small road...about 15 miles southeast of the airport...the smoke cleared rapidly as we maintained 160 mph until over the pasture at about 1,000 feet...we made a descending 360 degree turn...noted the position of the power lines, fences, buildings, cattle, and other obstacles, slowing to...90 mph...touched down about 150 feet past the fence...the field was relatively flat and covered with wet grass approximately 2 to 3 feet high. I had difficulty keeping the tailwheel from bouncing as we plowed through the high grass and had to make continuous rudder inputs to keep tracking straight. After approximately 300 feet of roll out, the aircraft yawed right, the left main collapsed under the aircraft, and we slid sideways onto the bottom left wing, which snapped off, taking the left upper wing with it. We went up the nose, rotated about 180 degrees counterclockwise, and stopped in an upright position...."

The engine was torn down under the supervision of the FAA, on May 16, 1999, at the McGee Tyson Airport, Knoxville, Tennessee. The teardown revealed that the No. 4 cylinder connecting rod bearing had evidence of scoring. The oil filter screen was found with steel particles. The No. 6 connecting rod had failed due to oil starvation. According to the FAA inspector, the cause of the oil starvation was "undetermined." The interior of the case was extensively damaged from the No. 6 connecting rod pieces. N260Z was equipped with a Lycoming aerobatic certified AEIO-540-D4A5 engine.