CHI94LA289

The pilot was attempting to soft field takeoff from a 2400 foot runway with 20 degrees of flaps. The gross weight of the airplane with 30 gallons fuel and 4 occupants was estimated at 2540 pounds. The maximum certified weight of the airplane was 2400 pounds. The calculated takeoff distance for the conditions was 1860 feet at 2400 pounds with a flap setting of 10 degrees. The pilot handbook recommends a 10 degree flap setting for short field takeoffs and that flap settings greater than 10 degrees are not approved for takeoff. The airplane contacted trees at the departure end of the runway and came to rest inverted. Post-crash operation of the engine at full throttle resulted in 2200 RPM.

On August 28, 1994, at 1632 hours central daylight time, a Cessna 172, N97618, operated as a rental aircraft by John Fini of Schaumburg, Illinois, landed in a field 3/4 mile from the departure end of runway 24 (2,400' x 100') at Olson Field, Plato Center, Illinois, and was substantially damaged. The airplane came to rest inverted. The private pilot and three passengers were not injured. Visual meteorological conditions existed at the time of the accident and no flight plan was filed.

The flight operated under 14 CFR Part 91, had originated from Schaumburg Airpark, Schaumburg, Illinois, and was returning after a stop at Olson Field. The pilot reported performing soft field takeoff procedures, setting 20 degrees of flaps (flaps were at 20 degrees after the accident), and that after becoming airborne the airplane did not climb. The pilot reported normal magneto operation during pre-takeoff checks, and 2200 rpm on takeoff. The pilot stated that the engine may have surged during his takeoff. None of the passengers could remember any power surges.

Post-crash inspection revealed no anomalies with the airplane. The engine was operated on the airframe, and developed 2200 rpm at full throttle. The magneto drop was less than 50 rpm with an engine setting of 1700 rpm. The total weight of the occupants was 840 pounds. The estimated fuel on board was 30 gallons (180 pounds). Aircraft empty weight was 1520 pounds. Total estimated weight at the time of the accident was 2540 pounds. The maximum certified weight in the normal category is 2400 pounds.

The distance required for takeoff over a 50 foot obstacle derived from the Cessna-172P Pilot Operating Handbook for a temperature of 20 degrees C, pressure altitude of 1000 feet, at a gross weight of 2400 pounds, with a 10 degree flap setting, is 1860 feet. There is no takeoff performance data available for gross weights above 2400 pounds, or for flap settings greater than 10 degrees.

The Pilot Operating Handbook, Section 4, Normal Procedures, calls for a flap setting of 10 degrees in the Short Field Takeoff checklist. Section 4, Normal Procedures, under "TAKEOFF, WING FLAP SETTINGS" states "Flap deflections greater than 10 degrees are not approved for takeoff."