Background
A private pilot, who had resumed flying three weeks earlier after a five-year layoff, was accompanied by a flight instructor in the right seat for a cross-country flight. The outbound leg concluded with an uneventful landing and taxi; no mechanical anomalies were noted.
The Incident
During the return leg at night, while on the downwind leg, the private pilot asked the flight instructor to take over the landing because she was unsure of the "perspective." The flight instructor assumed control, and the private pilot kept her hands and feet off the controls while observing the runway environment. On final approach, the private pilot turned on the landing light. The airplane touched down on both main landing gear, with the flight instructor holding the nose wheel off the runway. The private pilot, unable to see forward, perceived the airplane veering to the right. She then heard the flight instructor exclaim "oh shoot" and "something about the rudder." The airplane subsequently "hit something" and bounced, then veered left and stopped in the center of the runway.
According to the flight instructor, during the return leg he noticed the airplane deviating left of the intended heading multiple times. At some point, the private pilot stated she could not trim the airplane. The flight instructor attempted to trim it, and even with maximum right trim set, he still had to hold right rudder to maintain heading. He continued holding right rudder for the remainder of the flight.
At the destination airport, weather was "clear with light to nil wind." On final approach, the flight instructor set power between 1,700 and 1,800 rpm, and the airplane was stabilized at 70 knots and aligned with the center of the runway both visually and through glideslope and localizer indications. He held right rudder and adjusted heading by easing off or applying rudder as needed to maintain runway alignment. He considered using flaps but decided against it, uncertain whether they might exaggerate the left-turning tendency.
Approaching the runway, the flight instructor noticed the airplane turning right, so he eased off some right rudder. He then "totally removed right rudder pressure and started the transition approach to land," but "for whatever reason, the aircraft turned to the right suddenly and unexpected." To keep the airplane over the runway, he turned the controls left and applied full left rudder, but did not observe an immediate response. He advised the private pilot and a passenger of his actions, stating "the rudder is not responding" while initiating a go-around. He then heard a "bang" as if the airplane struck something, and the impact "forced the airplane more over and closer to the center if the runway." He aborted the go-around and landed.
Post-Landing Findings
After landing, while taxiing to the ramp, the flight instructor pressed both rudder pedals several times and noted that the right rudder pedal was much stiffer than the left. Photographs of the scene showed three wheel tracks to the right of the runway, consistent with the width of the airplane's landing gear. The tracks veered off the runway, with the right main landing gear track passing next to the remnants of a 3,000-foot remaining sign. The tracks then gradually veered back left and onto a taxiway toward the runway. A subsequent examination of the airplane for proper rigging revealed no significant anomalies.