The private pilot was on a local passenger flight in conjunction with a wilderness lodge operation operating under Title 14, CFR Part 91, when the accident occurred. The pilot said during landing at an off airport site he was in a left base to final turn when the left rudder became unresponsive. He said he was able to level the wings with the ailerons just before the airplane impacted the ground. The pilot said the takeoff and flight had been uneventful, but after the accident he and the passenger noted that the left rudder cable retaining bolt was missing. He said the left wing and fuselage received substantial damage during the impact with terrain. The pilot reported that the rudder cable connection is routinely inspected prior to every flight, and that prior to the accident flight no discrepancy was noted.