On November 14, 2008, at 1824 eastern standard time, an American General AG5B, N1191W, crashed into trees shortly after takeoff from the Wing South Airpark (FA37), Naples, Florida. The certificated private pilot sustained serious injuries, three passengers sustained minor injuries, and the airplane received substantial damage. The flight was operated as a personal flight under the provisions of 14 Code of Federal Regulations (CFR) Part 91, and no flight plan was filed. Night visual meteorological conditions prevailed at the time of the accident. The airplane departed on runway 36, a 4,400-foot-long, 100-foot-wide, asphalt runway. According to the pilot, he lost all memory of the accident, from the afternoon prior to departure, until waking up in the medevac helicopter enroute to the hospital. The pilot’s wife, was who also a certificated pilot, was occupying a rear seat. She stated that the takeoff was normal and the airplane lifted off and started to climb to about 100 to 150 feet above the ground. She then noticed that although the engine appeared to be running normally, the rpm were about 2,100, or 200 rpm below the 2,300 rpm she was expecting. She saw the pilot holding full forward pressure on the throttle and mixture controls. The airplane started to sink, losing altitude and the pilot selected the “high” setting on the electric fuel pump, but this did not have any effect and the engine continued to run smoothly. The sink continued and the airplane started to contact the trees and crashed into a wooded area. After exiting the airplane and dazed from the accident, three of the occupants were rescued by the fire department. Another passenger had to be extracted from the airplane and carried to the ambulance. According to a pilot-rated passenger, the liftoff and initial climb appeared normal, however, soon after it was apparent that the airplane was not accelerating. The passenger mentioned to the pilot that the airspeed seemed to be stagnating and he confirmed the same concern. The pilot and passenger both checked for full throttle position and rpm, which was at 2,150. The passenger stated that the only option at that point was to lower the nose in an attempt to increase airspeed. The passenger added that there was no increase in airspeed and they both realized that the airplane would impact trees. The passenger watched the pilot continue to fly the airplane straight and level to the point of impact. According to the owner of the airplane, who was also rated pilot and observed the departure, the airplane took off in about half of the runway length (2,200 feet) from the south end of the field, toward the north. The airplane climbed approximately 150 feet and appeared to be well above the height of the trees, then started to sink and disappeared into the trees, while at an increased pitch attitude. He stated that he loaned the airplane to the pilot for the evening flight. The owner added that the airplane was fueled from an above-ground fuel tank at FA37, which was for the use of the tenants, and that he had flown the accident airplane about 30 minutes since the last fueling. He estimated the fuel load on the airplane at the time of the accident to be 40 gallons. According to the right front seat pilot-rated passenger, the pilot weighed 175 pounds (lbs), he weighted 175 lbs, the two rear seat occupants weighed 130 lbs and 120 lbs, respectively, and the airplane had approximately 38 to 40 gallons of fuel onboard. The airplane’s actual weight and balance was not provided for examination. However, an estimated empty weight of 1,592 pounds was used for a basic weight and balance. Using the weights listed above, with 8 quarts of oil, and 40 gallons of fuel the airplanes estimated gross weight at takeoff would have been 2,463 pounds. The airplanes certificated maximum gross weight was 2,400 pounds. The center of gravity was not calculated because the airplane’s actual weight and balance was not located. The four-seat, low-wing, fixed tricycle gear airplane was manufactured in 1991. It was equipped with a Lycoming O-360, 180-horspower engine. Review of the airplane’s maintenance records revealed that the last annual inspection was completed on April 26, 2008, at a total airframe time of 1,247 hours. The closest weather reporting facility to the accident site was Naples Municipal Airport (APF), located approximately 4 miles north of the accident site at an elevation of 8 feet. APF weather observation at 1853, wind 170 at 05 knots, visibility 10 statute miles, ceiling clear, temperature 25-degrees Celsius ©, dew point temperature 22 degrees C, altimeter setting 29.92 inches of Mercury (HG). A review of the carburetor icing chart found that the temperature and dew point temperature were conducive to serious icing at glide power. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the airplane initially impacted the tops of trees in a level attitude, but as it fell to the ground, it was in an approximate 80-degree left bank. Both wings and the right horizontal stabilizer were separated from the fuselage and had severe impact damage from the trees. The propeller damage observed was consistent with the engine developing power, and the throttle and mixture controls were observed in the full forward position. On January 13, 2009, a representative of Lycoming Engines and the FAA inspector conducted a post recovery examination of the airplane wreckage at the facilities of Air & Sea Recovery, Inc., Ft. Pierce, Florida. A cursory examination of the engine was accomplished, and no evidence of any mechanical deficiency was found that would have prevented the engine from developing power prior to the accident. The engine was determined to be in test run worthy condition. Arrangements were made to transport the engine to the facilities of Certified Engines, Inc., Opa-Locka, Florida. On January 14, 2009, the representative of Lycoming Engines and the FAA inspector conducted an engine test run. Minor impact damage to the ignition harness was repaired and a substitute exhaust system was installed. The engine was mounted onto a test stand and with necessary provisions for fuel supply, and electric power supplied to the starter, the engine was started and operated for a period of about 2 minutes. After warm-up, the throttle was advanced and the engine operated normally. The engine attained full static rpm of 2,250. Operations were smooth and magneto checks were equal, with less than 100 rpm drop at 1,700 rpm. Idle power was smooth at 700 rpm. Examination of the wreckage by FAA inspectors did not reveal any evidence of a preexisting mechanical failure or malfunction.