What happened
On March 28, 1999, an Embraer 720 D, registration PT-RRX, was performing a visual flight rules (VFR) mission from Santarém to Óbidos, Brazil. Approximately twenty minutes into the flight, while cruising at 1,600 feet, the aircraft experienced an engine failure. The pilot attempted to restart the engine by switching to the right fuel tank, but the attempt was unsuccessful, as the engine exhibited characteristics of a fuel system failure.
Due to the low altitude and distance from the nearest runway, the pilot opted to perform a forced landing on Lago Curuai, near a small village. The pilot emerged uninjured, but the aircraft became submerged in the lake.
The investigation
CENIPA investigators examined the aircraft's maintenance records and flight logs, uncovering significant irregularities. The investigation found that the engine and propeller logbooks were outdated and that maintenance services were inadequate and not performed periodically. Furthermore, the aircraft's flight logs were not being accurately maintained; a comparison between the aircraft's logs and Santarém Tower records revealed that the actual flight hours exceeded the hours declared in the documentation. This discrepancy allowed the owner to improperly extend mandatory inspection intervals.
Because the aircraft was submerged, a direct technical examination of the engine was not possible. However, investigators noted that the engine had been removed from the lake for insurance purposes without the authorization of the investigation commission. The investigation also noted that the aircraft lacked a hangar and was exposed to frequent regional rains.
Findings
- Inadequate maintenance oversight: The aircraft's maintenance was irregular, and there were no records of compliance with Airworthiness Directives (AD) or Service Bulletins.
- Fuel system vulnerability: The pilot failed to perform a fuel tank drain prior to departure and demonstrated a lack of knowledge regarding this procedure. This, combined with the aircraft's exposure to rain, created a high risk of water contamination in the fuel system.
- Operational irregularities: There were indications that the aircraft may have been used for unauthorized commercial passenger transport, contributing to the excessive flight hours.
- Human factors: The pilot was not wearing required corrective lenses during the flight.