Accident Summary
A private pilot flying a cross-country personal flight under Title 14, CFR Part 91 was searching for potential landing areas near a cabin on a remote island. The pilot scanned the area at 400 feet above ground level (agl) for about 15 to 20 minutes. The airplane was configured with 20 degrees of flaps, carburetor heat on, and an engine power setting of about 18 to 20 inches of manifold pressure. The outside temperature was 52 degrees Fahrenheit.
Flight Sequence
After spotting the cabin, the pilot began a descent for a low-level pass along a beach. The airplane was configured to full flaps, engine power near idle, and carburetor heat on. When the pilot attempted to add engine power to level the airplane, the engine did not respond. The pilot pushed the throttle in and out several times without any change in power from idle. The airplane continued to descend. As the wheel began to strike low brush, the engine went to full power, but the airplane touched down in rough terrain and nosed over. The accident resulted in structural damage to the fuselage and wings.
Pilot's Previous Report
In the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1), the pilot indicated that during the flight to the island, the engine had developed a slight roughness accompanied by an approximate 1-inch drop in manifold pressure. The carburetor temperature gauge indicated -35 degrees Fahrenheit. The pilot applied carburetor heat, which raised the carburetor temperature to about 0 degrees Fahrenheit, but no further. The pilot then reduced engine power to idle, reapplied carburetor heat, and after about 1 minute, the carburetor temperature increased to about 55 degrees Fahrenheit, which resolved the engine roughness.
The pilot reported that he had experienced a carburetor heat problem about 8 months prior to the accident. After a normal landing at an airport, he attempted to apply engine power for takeoff, but the engine would only produce about 14 inches of manifold pressure with carburetor heat on. After several seconds of idling the engine with full carburetor heat applied, full power was restored.
Investigation
The airplane was recovered from the island, but the engine was not examined by FAA or NTSB personnel. The pilot indicated that the airplane had received an annual inspection in February 2006, and he had flown the airplane for about 120 hours without a repeat of the carburetor heat problem.