On February 22, 1994, at 1915 Pacific standard time, a Cessna 421C, N7039T, sustained structural damage to the forward fuselage and nose gear trunion when the aircraft ran off the runway while taxiing for takeoff at Tulare, California. The aircraft was owned by Van Ryn Feed Company Inc., of Corona, California, and was on a cross-country personal flight conducted under 14 CFR Part 91. Visual meteorological conditions prevailed at the time and no flight plan had been filed for the operation. The certificated private pilot and the passenger on board were not injured. The flight originated at Chino, California, at 1730 on the day of the mishap. Federal Aviation Administration inspectors reported that during the hours of darkness the pilot was preparing to make a right turn onto the approach end of runway 13 from a parallel taxiway when he lost control of the aircraft and ran off the taxiway into a ditch. The force of the impact drove the nose gear back into the fuselage causing substantial structural damage. In his written statement, the pilot reported that he had landed at Mefford Field to drop off three of his four passengers. As he taxied to the ramp, he noticed that his right brake felt "mushy" and he had a "little problem" in making two 90-degree right turns. As he continued to make two more 90-degree right turns, his brakes began to function normally. After deplaning his passengers, the pilot checked the braking action of both his right and left brakes and they responded normally. He proceeded to taxi back to runway 13 along a parallel taxiway until he reached a 45-degree intersecting taxiway connecting the parallel taxiway with the approach end of runway 13. He stated that as he applied his brakes to make the turn, he obtained no braking action. The aircraft continued straight ahead off the end of the taxiway and into a ditch where it impacted soft terrain. The force of the impact collapsed the nose gear and allowed both propellers to contact the ground. A postaccident technical inspection of the brake system revealed no discrepancies or abnormalities.