On December 9, 2001, about 1745 hours Hawaiian standard time, a Cessna 150K, N6136G, experienced a total loss of engine power during cruise flight. The pilot made a forced landing in a park on the Island of Oahu, and during rollout the airplane collided with a tree. The airplane was operated by Oahu Aviation Flight School, Inc., Honolulu, Hawaii, and it was substantially damaged. The private pilot received a minor injury, and the passenger was not injured. Visual meteorological conditions prevailed during the dusk flight, and no flight plan was filed. The flight was performed under 14 CFR Part 91. The round-robin flight originated from the Honolulu International Airport on Oahu about 1530. The pilot reported that he believed the airplane's fuel tanks were full, but he may have "misjudged" their actual quantity. After takeoff, the pilot flew to the Island of Lanai, and arrived there about 1620. While on Lanai, the pilot did not check the amount of fuel in the tanks. The pilot departed Lanai about 1650 and planned to return to Honolulu. The pilot reported that while en route the engine lost power. At the time, the fuel tank gauges registered slightly less than 1/2 full. Unable to reach his destination, the pilot made a forced landing in the Waialae Iki Park (about 8 miles east of the Honolulu International Airport). During rollout, the airplane collided with a mango tree. According to the operator, the pilot had been scheduled to rent the airplane between 1400 and 1600, but he had been delayed for undetermined reasons. The airplane's fuel tanks were not full upon the pilot's departure from Honolulu. The total time registered on the engine's tachometer (from Honolulu to Lanai to impact) was approximately 1.9 hours. The operator reported that after the accident the airplane was examined. The undamaged right wing fuel tank was found containing several drops of fuel. The damaged (but not breached) left wing fuel tank contained about 1 quart of fuel. The operator also stated that the airplane's engine burns approximately 6 gallons per hour. According to the Cessna Aircraft Company, the airplane's fuel tank capacity is 26 gallons. The total usable fuel in all flight conditions is 22.5 gallons.