Event Overview
On August 8, 2012, at approximately 1930 central daylight time, an experimental amateur-built Ristine Avid Mark IV airplane, registration N1328L, departed the paved surface of runway 12 at Poplar Grove Airport (C77), near Poplar Grove, Illinois, following a loss of directional control. The airline transport pilot, the sole occupant, reported no injuries. The airplane sustained substantial damage to the empennage.
Flight Details
The aircraft was registered to and operated by the pilot under the provisions of 14 Code of Federal Regulations Part 91 as a personal flight. Visual flight rules (VFR) conditions prevailed, and no VFR flight plan was filed. The local flight originated from C77 at approximately 1910.
Pilot Account
According to the pilot, he performed approximately ten landings during light and variable wind conditions on the hard surface runway. All landings were on centerline with no drift or tire protest, and were three-point near-stall landings. During the final landing, the airplane was on centerline and straight with no left drift tendency until a sudden, uncontrolled jerk to the left occurred. The pilot indicated that the motion could not be stopped with opposite rudder input. The aircraft rolled off the runway onto smooth grass, continued, and ultimately came to rest in long grass approximately 150 degrees from the landing direction.
Examination Findings
A Federal Aviation Administration inspector examined the airplane. The inspection revealed that the lower right side longeron tail-spring support area had failed due to excessive corrosion.