On July 28, 2002, at 0906 eastern daylight time, a Cessna 150H, N6486S, registered to Griffin Flight School, Inc., and operated by Peachtree Flight Center, collided with trees during a forced landing in Senoia, Georgia. The instructional flight was operated under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed at the time of the accident. The certificated flight instructor and the student pilot reported no injuries, and the airplane sustained substantial damage. The local flight departed Peachtree City Falcon Field in Peachtree City, Georgia, at 0830. The flight instructor stated the student was performing a simulated engine failure with power at idle and had descended from 2,500 feet above mean sea level to 500 feet above the ground. When the throttle was advanced to recover from the descent, the engine did not respond. Attempts by the flight instructor to restore engine power were not successful. The flight instructor maneuvered the airplane for a forced landing, and it collided with a stand of small pine trees. The flight instructor stated carburetor heat was used during the simulated engine failure maneuver. The student pilot stated carburetor heat was not used during the maneuver. The flight instructor reported no abnormalities with the engine prior to the event; he stated the magnetos, carburetor heat, throttle, and mixture controls functioned normally during run-up and cruise. Examination of the wreckage revealed the cowling was separated at the firewall, the lower tubes of the engine mount were broken, the tail section was separated, and both wingtips displayed crush damage. Fuel was observed leaking from the wreckage and was stopped by turning the fuel selector valve to the "off" position. About 12 gallons of fuel was recovered from the tanks. On August 9, 2002, the engine was examined on the airframe at a recovery facility. The severed engine mounts were welded to stabilize engine movement. Repairs were made to the propeller spinner and oil filter adapter, which sustained damage during impact. Provisions were made for fuel supply, and the engine was started from inside the cockpit and controlled using the throttle and mixture controls. The engine ran smoothly at speeds ranging from idle to 2000 rpm. A magneto check was performed at 1500 rpm, and each magneto operated within normal parameters. The operation of the engine was limited to 2000 rpm for the safety of personnel. No defects were observed during the engine run that would have prevented normal operation. A review of icing probability curves for conditions favorable to the formation of induction system icing reveals the temperature and dew point reported at the time of the accident fall within the "serious icing, glide power" range. The Owner's Manual for the Cessna 150 states in the Before Landing on page 1-2 the procedures for descent are as follows: 1. Mixture - rich, 2. Carburetor Heat - apply full heat before closing throttle.