What happened
On October 17, 2020, at approximately 12:30 UTC, an INPAER Explorer (registration PR-ZSL) departed from the CAVU Aerodrome in Raposa, Maranhão, bound for Aquiraz, Ceará. The aircraft was operating a private flight with a pilot and two passengers on board. Shortly after takeoff, the aircraft experienced a loss of engine power. The pilot attempted an emergency landing along the banks of the Paciência River, which resulted in the aircraft becoming submerged. While the aircraft sustained substantial damage, all three occupants escaped the wreckage without injury.
The investigation
CENIPA investigators examined the aircraft and its components to determine the cause of the power loss. The investigation confirmed that the pilot was properly licensed and medically certified, and the aircraft held valid experimental flight authorizations. Although the pilot had extensive flight experience, they had only 30 minutes of flight time in this specific model.
Investigators analyzed the fuel system, including the tanks, lines, and pumps, finding no obstructions or contamination that would have caused a fuel starvation event. The investigation also noted that the aircraft's maintenance logs and engine records were lost when the aircraft became submerged.
During the inspection of the engine, investigators found moderate corrosion, which was largely attributed to the aircraft being submerged in saltwater. However, the investigation also identified severe galvanic corrosion on the magnetos and internal corrosion within the igniters. Because the aircraft was based near the coast, investigators considered the possibility that pre-existing corrosion from salt air exposure might have been present prior to the accident.
Furthermore, the investigation found that the oil filter had been in service for over four months. According to the manufacturer's service bulletin, engines operating in coastal environments require more frequent oil changes than the standard 50-hour interval. While the filter appeared clean, the maintenance schedule for the engine was not being strictly followed according to the manufacturer's specific requirements for maritime environments.
Findings
- Pre-existing corrosion on the magnetos is considered a potential cause of the engine power loss.
- The aircraft's maintenance interval for oil changes was not being performed in accordance with the manufacturer's recommendations for coastal operations.
- The loss of aircraft documentation during the submersion prevented a definitive determination of the engine's full maintenance history.