SEA01LA002

The pilot reported that during the landing roll, the tail wheel equipped airplane suddenly veered to the left and exited the side of the runway onto the grass. The pilot applied corrective action and opted to go-around when he observed a debris pile in his line of travel. The aircraft did not clear the debris pile and the horizontal stabilizer collided with an obstruction. The airplane nosed down and over, coming to rest inverted. During the accident sequence, the tail wheel separated from the attachment/pivot point, and the axle shaft was broken. An independent metallurgist visually inspected the axle shaft and reported that the failure was due to overload. No mechanical failures or malfunctions were found during the main landing gear inspection of the wheel brake assembly.

On October 8, 2000, about 1400 Pacific daylight time, a WSK-PZL Warzawa-Okecie PZL-104 Wilga 80, N80EG, registered to and operated by the airline transport pilot as a 14 CFR Part 91 personal flight, veered off the runway at Stark's Twin Oaks Airpark, Hillsboro, Oregon, and collided with ground debris. Visual meteorological conditions prevailed at the time and no flight plan was filed for the local flight. The aircraft was substantially damaged and the pilot and his passenger received minor injuries.

During a telephone interview and subsequent written statement, the pilot reported that the landing on runway 2 was normal with the main landing gear touching first, then the tail wheel. The pilot reported that the aircraft was rolling out at approximately 25-30 knots when it suddenly veered to the left. The pilot applied full right rudder control with little braking action. The aircraft continued to the left and the pilot applied full right braking action with no effect. The airplane exited the side of the runway onto the grass heading for a debris pile located about 75 feet from runway centerline. The pilot reported that he then applied full power to takeoff for the go-around. The aircraft straightened out and the pilot pulled back on the control stick. The airplane lifted off just prior to the left side elevator striking a three-foot high concrete block among the debris pile. The aircraft touched down beyond the debris pile and nosed over.

Later the pilot reported that the tail wheel axle broke on touch down and caused the airplane to veer to the left.

During a telephone interview with the passenger, she reported that everything seemed normal until the landing roll when the airplane suddenly veered to the left "steeply" and exited the side of the runway onto the grass. She stated that she saw the pile of debris and that the pilot added power. She stated that she thought that the airplane did lift off, but then nosed down and over.

Witnesses reported that the aircraft had just landed when it suddenly veered to the left. Engine power was heard to increase as the aircraft exited the side of the runway at about mid-field. The aircraft traveled about 40 feet when the aircraft struck a pile of debris. The airplane then nosed down and subsequently nosed over, coming to rest inverted.

The Federal Aviation Administration Inspector from the Hillsboro, Oregon, Flight Standards District Office (FSDO), who responded to the accident site reported that he observed a single tire tread mark that departed the left side of the runway and continued in the grass for about 80 feet. The debris pile was located about 40-feet from the runway edge. The debris pile was approximately 50 feet beyond and in line with the end of the tire mark in the grass. A cement block measuring about three feet in height was among the debris in the pile. The inspector noted red, white and blue paint chips on and around this block. About 10 to 15 feet from the cement block, the inspector found a damaged section of the horizontal stabilizer STOL fence which is painted red, white and blue. About 80 feet from the debris pile, the main wrecked came to rest inverted. The tail wheel was found about half way between the debris pile and the wreckage. The inspector reported that he inspected the main wheel assemblies. The left main wheel was undamaged and free spinning. The brake assembly appeared intact and functional. The right main wheel was damaged, but the brake assembly appeared intact. The tail wheel assembly appeared intact, however, the tail wheel attachment/pivot point was damaged.

On October 31, 2000, another inspector from the FSDO inspected the main wheel brake assembly and the steerable tail wheel assembly. The inspector reported that the brake cylinder and housing was functional. The hydraulic piston did not bind on application and the housing was free to follow the action of the brake disc. During the inspection of the tail wheel, the inspector found that the tail wheel axle shaft was broken.

The axle shaft was taken to Northwest Labs, Seattle, Washington, by the pilot's insurance company's insurance adjuster from Pac Northwest, Redmond, Washington. The metallurgist visually inspected the axle shaft and reported that the failure was due to overload.