What happened
On February 25, 2020, a Cessna 170A, registration PP-DXR, departed from Itanhaém Aerodrome (SDIM) for an aerial advertising mission involving banner towing. The flight, operated by Visual Propaganda Aérea Ltda., proceeded along the coast of São Paulo. During the return leg of the flight, while flying at approximately 600 feet above sea level near Praia do Tombo, the pilot reported a loss of engine power characterized by intermittent operation and engine failure.
Unable to maintain altitude for an emergency landing at a nearby airfield, the pilot performed an emergency water landing in the sea. The aircraft subsequently submerged and was not recovered. The pilot survived the incident uninjured.
The investigation
CENIPA investigators examined several hypotheses regarding the engine power loss. Because the aircraft was never located due to strong tidal currents and the corrosive effects of seawater, physical analysis of the engine or wreckage was impossible. Investigators ruled out fuel contamination, as previous flights on the same fuel source had been successful. They also found that a total fuel exhaustion was unlikely based on calculated consumption rates, which suggested the aircraft had sufficient endurance for the flight duration.
The investigation focused on the possibility of asymmetric fuel consumption or improper fuel management. The aircraft's fuel system relied on gravity, with a selector switch capable of selecting both tanks, the left tank, or the right tank. Investigators noted that the increased drag from the banner and the presence of headwinds during the return leg would have increased fuel consumption. The investigation also identified discrepancies between the operator's emergency manual and the aircraft's manufacturer checklist regarding fuel selector procedures during engine failure.
Findings
- The engine power loss was likely linked to improper fuel management or an unmonitored fuel imbalance.
- The pilot's attention and situational awareness during the monotonous nature of the long-duration, level flight over the sea may have been compromised.
- There was a lack of standardized procedures in the operator's manual regarding fuel selector use during engine failure, creating a discrepancy with the aircraft's checklist.
- The operator's safety management system lacked specific risk mitigation for fuel management and periodic fuel checks during banner towing operations.
- Emergency training for engine failure over water was conducted only once upon initial entry to the company, without a requirement for recurrent training.
Safety action
CENIPA issued recommendations to the National Civil Aviation Agency (ANAC) to ensure the operator implements better risk identification for fuel management in their Safety Management System (SMS). Additionally, the operator was advised to re-evaluate the frequency and methodology of engine failure training and to standardize emergency procedures and periodic fuel checks in their manuals.