HISTORY OF FLIGHT: On January 25, 1994, at 1612 central standard time, an Aeronca 7AC, N84212, was substantially damaged following during a forced landing near Tulsa, Oklahoma. The flight instructor sustained minor injuries while the pilot rated passenger was fatally injured. Visual meteorological conditions prevailed for the personal flight. The instructor reported that just after takeoff, during the initial climb, he experienced a loss of engine power due to what he thought was carburetor icing. He further stated that he initiated a turn back to the runway, saw a light pole, and while maneuvering to avoid the light pole lost control of the airplane. The instructor further reported that he did not apply carburetor heat. Witnesses observed the airplane crossing 21st Street at a low altitude, heading south. The airplane was observed establishing a steep angle of climb, followed by a sharp turn to the east and the nose dropping towards the ground. PERSONNEL INFORMATION: The commercially rated instructor pilot was also an airframe and powerplant certificated mechanic and had performed all the required maintenance on the airplane since he purchased it on October 15,1989. The passenger was a private pilot. He was being given a demonstration flight in a tail wheel type airplane to determine future flight instruction. AIRCRAFT INFORMATION: A review of the airframe and engine records by the FAA inspector did not reveal any anomalies or uncorrected maintenance defects. WRECKAGE AND IMPACT INFORMATION: Witness marks were found on the eastbound lane of 21st Street at 137th East Avenue and the airplane came to rest on its nose, up against the center median. Flight control continuity was established to all flight controls. Likewise, engine continuity was established. The carburetor heat was off and the selector control was in the mid range. Examination of the airplane and engine did not disclose any mechanical problems. METEOROLOGICAL INFORMATION: The temperature was 60 degrees fahrenheit with a dew point of 51 at the time of the accident. According to the carburetor icing probability chart this places the airplane in the serious icing range at cruise power. The copy of the chart is enclosed with the report. ADDITIONAL DATA: The wreckage was released to the owner.