Accident Details
On November 13, 2012, at about 1720 eastern standard time, a Piper PA-18-150, registration N9764P, was substantially damaged during the landing rollout following a forced landing to a field near Canton, Georgia. The airline transport pilot and a passenger were not injured. The flight was conducted under 14 Code of Federal Regulations Part 91 as a personal flight, originating at Air Acres Airport (5GA4), Woodstock, Georgia, about 1650.
According to the pilot, while performing flight maneuvers at 2,500 feet mean sea level (msl), he descended to 2,000 feet msl and noted that engine rpm and airspeed began to decrease. The pilot checked the throttle position, mixture control, fuel selector, magneto selection, and cycled the carburetor heat, but was unable to regain full engine power. With only partial engine power available, he elected to land in a nearby field, using full flaps and a side slip maneuver. After clearing trees, the pilot landed on a grass field. The airplane struck a slightly raised path in the field, bounced, nosed over, and came to rest inverted. The pilot turned off the fuel selector and battery before exiting.
Post-Accident Examination
Inspection of the engine after the cowl was removed revealed a hole worn in the lower section of the engine cowl. When the cowl was reinstalled, it was noted that the carburetor heat control arm had little clearance from the lower cowl, and the hole in the cowl was in the vicinity of that arm. The carburetor heat control arm would contact and catch on the lower cowl when pressure was applied. When the carburetor heat was pulled to the ON position, the arm would catch on the cowl, limiting the application of carburetor heat.
The pilot stated that the lower engine cowl was fabricated to fit the airplane. During a postaccident examination of the cowl with a Federal Aviation Administration inspector, the pilot noted that the lower cowl did not have adequate clearances from the engine.
The most recent annual inspection was performed on September 20, 2012. At that time, the engine had accumulated 1,034.7 hours of total time in service and 141.3 hours since overhaul.
Weather Conditions
The 1715 automated weather observation at Cherokee County Airport (CNI), located near the accident site, reported wind from 300 degrees at 6 knots, visibility 10 miles, clear skies, temperature 10°C, dew point -5°C, and an altimeter setting of 30.27 inches of mercury. According to the Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, the carburetor icing probability chart indicates a probability of icing at cruise/glide power for the temperature and dew point conditions reported around the time of the accident.