The accident occurred during the first flight since an annual inspection was performed on the airplane. The pilot reported that the airplane was last fueled approximately 5 months before the accident flight, at which time the fuel tanks were topped-off. According to the pilot, after being refueled the airplane was flown about 30 minutes to the accident airport where the annual inspection was performed. The Inspector Authorization (IA) mechanic who performed the annual inspection stated that he ran the engines for about 30 minutes before the annual and about 40 minutes after the inspection was completed. The IA mechanic did not refuel the airplane after the annual inspection. The pilot told a Federal Aviation Administration (FAA) inspector that he did not visually check the fuel tank levels before the accident flight. The pilot stated that after takeoff he remained in the traffic pattern and performed a full stop landing. He then back-taxied on the runway before his next takeoff. After the second takeoff, during initial climb, the pilot noticed that the rear engine was losing power. He applied full power to the forward engine and was able to maintain sufficient altitude to clear a tree line, but the airplane was losing airspeed. He then performed an off-field landing approximately 4 miles from the departure airport. The airplane landed in a soft field, during which the landing gear collapsed and the fuselage, left wing, and left stabilizer were substantially damaged. The pilot stated that after the accident he visually inspected the right main fuel tank and found it empty. He indicated that he had been running the rear engine on the right main fuel tank during the accident flight. A postaccident inspection by a FAA inspector revealed the left main and left auxiliary fuel tanks contained 14 gallons and 17 gallons, respectively. The right main and right auxiliary fuel tanks contained 3 ounces and 3 gallons, respectively. The fuel selectors were all found turned off at the accident site. The rear engine was started and operated between an idle power setting and 1,500 rpm without anomalies. The engine responded to throttle inputs and both of its magnetos were operational during the test run.