CHI96LA064

While making a precautionary landing the pilot applied carburetor heat during the downwind leg of his approach to a road. It was removed a short time later. While on final approach the pilot said the airplane began descending too rapidly. He said he applied power and the engine did not respond. The pilot said the airplane drifted to the right as it neared the road. He said he applied left aileron and it continued to drift to the right. The pilot said he could not recall if he had applied right rudder when he applied left aileron. The pilot said the ailerons didn't respond because the airplane was too slow. The airplane landed in snow next to the road and nosed over. The on-scene investigation found no mechanical anomalies that would prevent normal flight. According to pilot/operator handbook for the Bellanca 7GCBC, the pilot is directed to use carburetor heat only when 'atmospheric conditions indicate that icing is probable....' The temperature and dew point were 17 and 12 degress F. respectively. The FAA's carburetor icing chart shows carburetor icing was probable.

On December 28, 1995, at 1100 central standard time (cst), a Bellanca 7GCBC, N88384, piloted by a commercially certificated pilot, was substantially damaged during a precautionary landing. The 14 CFR Part 91 public use flight was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot and passenger reported no injuries. The flight local departed Devils Lake, North Dakota, at 0815 cst.

During the return flight to the departure airport the pilot said he noticed fog "...between [his] position and Devils Lake... ." He said he decided to land heading west on an east-west road because there was a 10 to 15 knot wind from the southwest. While on final approach the pilot said the airplane began to descend too fast. He said he added power and the engine did not respond. As the airplane neared the road, the pilot said it began drifting to the right. He said application of left aileron did not change the airplane's drift direction. The airplane landed in deep snow on the road's north side and nosed over shortly after touching down.

During an interview the pilot said he had the engine throttled back, but could not recall how far. He said he had temporarily applied carburetor heat earlier on his downwind leg. The pilot was asked if he applied right rudder when he had applied the left aileron for drift correction. He said he could not recall. The pilot said the ailerons were not responsive when he moved them to the left. He said he felt the reason for this was that his airspeed was too slow.

The on-scene investigation was conducted by Federal Aviation Administration (FAA) Principal Maintenance and Operations Inspectors (PMI and POI). The PMI said he did not find any anomalies with the engine or control system that would prevent normal flight. He said the wing fuel tanks were about half full. The POI said the pilot told him he jammed the throttle full forward when he realized he needed power to slow the airplane's descent.

The pilot was asked if he observed a change in engine RPM when he had applied carburetor heat. He said there was no indication of carburetor icing at the time he applied the carburetor heat. According to the Bellanca 7GCBC pilot's operating handbook, "...do not use carburetor heat when landing unless atmospheric conditions indicate that icing was probable... ." The reported temperature/dew point (17 and 12 degrees Fahrenheit respectively) at Devils Lake Municipal Airport, Devils Lake, North Dakota. According to the FAA's carburetor icing probability chart, there was the possibility for light carburetor icing during glide or at cruise power. Copy of the chart is appended to this report.

FAA Advisory Circular AC-91-13C states in part that when operating in cold air "...there may be a problem of keeping the engine warm enough for high power operation if needed. It may be desirable to use more power than normal..." during the descent. FAA Advisory Circular AC-20-113 says that carburetor "...heat should be applied for a short time to warm the induction system before beginning a prolonged descent with the engine throttled back and left on during the descent."