What happened
On September 8, 2017, an Embraer EMB-711B, registration PT-NRR, was performing a cargo transport flight from Breves to São Sebastião da Boa Vista, Brazil. Approximately 25 minutes into the flight, the pilot experienced intense engine vibrations followed by an explosive sound and total engine failure. The failure caused oil to spray onto the windshield, significantly obscuring visibility.
The pilot performed an emergency landing in a swampy area on Marajó Island. During the landing, the aircraft's left wing detached upon contact with the marshy surface, and the airframe rotated approximately 135 degrees before coming to a complete stop. The pilot sustained minor injuries, while the two passengers remained uninjured. The aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the engine components, including cylinder #2, pistons, and various bolts. The investigation focused on the engine's overhaul history and maintenance records. Investigators found that while the aircraft had a valid airworthiness certificate, the maintenance logs for the airframe, engine, and propeller were not properly updated.
Specifically, the investigation scrutinized the engine overhaul performed in April 2007. According to Service Bulletin nº 240T, certain components, including engine studs, must be replaced during an overhaul regardless of their apparent condition. However, the operator's documentation failed to confirm whether these studs had been replaced during the 2007 service.
Findings
- The primary cause of the engine failure was a fatigue fracture of an engine stud near cylinder #2, which subsequently led to the overload failure of other engine components, including connecting rod bolts and pins.
- Inadequate maintenance processes and organizational failures contributed to the accident, as the operator failed to provide definitive proof that mandatory parts replacement, as required by Service Bulletin nº 240T, had been performed.
- Inadequate management oversight regarding the verification of maintenance execution and the updating of aircraft logbooks was identified as a contributing factor.
Safety action
CENIPA issued recommendations to the National Civil Aviation Agency (ANAC) to:
- Ensure the operator improves administrative and operational mechanisms for receiving, recording, and verifying maintenance services.
- Disseminate the findings of this investigation to alert EMB-711B operators and maintainers regarding the importance of complying with Service Bulletin nº 240T and accurately recording all part replacements.