On September 10, 1999, a Cessna 170B (registration N3476D) was involved in an aviation accident near Auburn, WA. Investigators recorded the probable cause as: Loss of directional control due to deficient brakes and tailwheel. Factors include leaking brake cylinder, loose tailwheel casting, and obstructions (VASI lights) in the path of the airplane as it left the runway. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported a heavy tailwheel vibration after a three-point touchdown, causing the airplane to veer left and depart the runway, striking VASI lights. Inspection revealed a leaking right brake cylinder and loose tailwheel mounting.
Event Description
According to the pilot's account, the landing was a three-point touchdown. Immediately after touching down, he experienced severe shaking or vibration from the tailwheel area, and the airplane began to veer to the left. He applied right rudder and right brake in an attempt to correct the deviation, but the airplane continued left and departed the runway at low speed. The airplane then struck VASI (Visual Approach Slope Indicator) lights, resulting in damage to the right side aft fuselage and the elevator.
Witnesses at nearby hangars reported hearing the vibration and observing the tailwheel oscillating from side to side after what they described as a very smooth touchdown.
Findings
Investigators from the Federal Aviation Administration (FAA) examined the damaged airplane and identified two discrepancies: the right brake cylinder was leaking, and the tailwheel casting was loose at its attachment point with the tailwheel leaf spring.