What happened
On March 24, 2014, an EMB-720C operated by Cururupu Táxi-Aéreo Ltda. departed from the São Luís Aerodrome (SBSL) in Maranhão, Brazil, for a scenic flight over the Lençolenses Maranhenses region. Approximately 25 minutes into the flight, while over the rural area of Humberto de Campos, the pilot noted abnormal engine noise accompanied by rising oil temperatures. Shortly thereafter, the engine suffered a sudden shutdown.
The pilot successfully performed an emergency landing in an uninhabited rural area. All 6 occupants—the pilot and five passengers—were uninjured, though the aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the engine, which had previously undergone an overhaul and been reinstalled following a 2007 accident involving substantial damage to the crankshaft, block, and internal components. The investigation revealed that the engine failure was caused by the breakage of the connecting rod head of cylinder number 6. This failure was triggered by an obstruction in the lubrication hole of the number 6 rod journal, which also showed signs of material forging throughout its extent.
Investigators identified a discrepancy regarding the engine's components, noting that the installed crankshaft possessed a different part number than those specified in the manufacturer's parts catalog and engine history. Furthermore, there was a lack of documentation to verify the measurements, clearances, or the traceability and origin of the parts installed during the overhaul. Due to the disintegration of the bearing and rod head during the failure, the root cause of the lubrication hole obstruction could not be definitively determined.
Findings
- Maintenance of the aircraft
- Use of a crankshaft with a part number inconsistent with the manufacturer's specifications.
- Lack of documentation regarding the traceability and technical approval of parts installed during the engine overhaul.