What happened
On November 22, 2016, a private Cessna 175C, registration SP-FYZ, was conducting a flight from Przasnysz to Warszawa Babice via Bobrowniki. During the flight, in the vicinity of Błonie, the pilot experienced intermittent engine power interruptions and reported the issue to FIS Warszawa. To maintain safety margins in the event of further power loss, air traffic control instructed the pilot to climb to 2,500 feet, which was completed.
Upon arriving near the EPBC aerodrome, the pilot established contact with Babice Info and was granted priority for landing on runway 10. As the aircraft entered the final approach, the engine power interruptions became more severe, and the engine ultimately shut down just above the runway threshold. Despite the loss of power, the pilot successfully completed the landing and the subsequent rollout without further incident. The aircraft was then towed to a hangar.
The investigation
The investigation focused on determining why the engine failed despite the pilot having the carburetor heat active during the flight. Post-flight inspections and engine tests, including checks of the magnetos, carburetor heat, and propeller pitch, were performed and showed no immediate defects. However, a detailed technical inspection of the engine system revealed a loose duct responsible for delivering heated air to the carburetor.
Findings
- The primary cause of the engine failure was carburetor icing within the fuel system.
- The icing was caused by a loose duct leading warm air to the carburetor, which compromised the effectiveness of the carburetor heat system.
- Atmospheric conditions at the time were conducive to the formation of icing in flight.
- The aircraft was sufficiently fueled and the pilot was fully qualified with valid medical certification.