What happened
On April 10, 2019, a Cessna 182N, registration PT-DYG, was performing a ferry flight from Palmas, TO, to Goiânia, GO, for an annual maintenance inspection. The flight was being conducted by a single pilot. During the descent, the pilot encountered light rain and decided to descend to FL065 to stabilize the aircraft. Shortly after reaching this altitude, the engine failed.
The pilot attempted an in-flight restart following the procedures outlined in the Quick Reference Handbook (QRH). Although the engine briefly restarted, it failed again after only a few seconds. Following a second unsuccessful restart attempt, the pilot executed an emergency landing in a watermelon plantation near Santa Isabel, GO. The aircraft sustained substantial damage, including a broken landing gear, but the pilot emerged unharmed.
The investigation
CENIPA investigators examined the aircraft's engine, fuel systems, and maintenance records. The investigation confirmed that the aircraft was airworthy, within weight and balance limits, and that all maintenance logs for the engine, propeller, and airframe were up to date. Fuel samples taken from both wing tanks were tested and found to meet all regulatory specifications.
Upon disassembly and bench testing, the engine and all fuel lines, filters, and pumps showed no signs of mechanical failure or blockage. Meteorological data from a nearby automated station in Itapaci, GO, indicated high relative humidity (80%) and temperatures conducive to ice formation. Investigators specifically noted that the carburetor heat lever was found in the 'OFF' position.
Findings
- The primary cause of the engine failure was carburetor icing, which restricted the fuel-air mixture to the engine.
- Atmospheric conditions, characterized by high humidity and specific temperature ranges, were highly favorable for severe carburetor icing, particularly when operating at reduced power settings.
- The pilot did not activate the carburetor heat during the descent, despite the presence of moisture and the potential for icing.
- Adverse meteorological conditions contributed to the occurrence.