What happened
On November 16, 2008, a Neiva EMB 720D, registration PT-RVS, operated by Roraima Táxi-Aéreo, departed Boa Vista International Airport (SBBV) for Surucucu (SWUQ) carrying a pilot and five passengers. Approximately 25 minutes into the flight, the pilot noticed a vibration in the engine. Although the pilot initially attempted to mitigate the vibration by adjusting propeller pitch and reducing power, the engine eventually suffered a total failure.
Following the engine failure, the pilot declared an emergency and sought an alternative landing site. After receiving information from another aircraft regarding a disused airstrip near the Mucajaí River, the pilot attempted a landing at a plantation in the Fazenda Liberdade area, near Alto Alegre, Roraima. During the approach, the pilot executed a left turn to clear obstacles and entered a stall maneuver to touchdown. The aircraft landed with a high sink rate and was misaligned with the runway, causing the left landing gear to collapse. The aircraft sustained substantial damage, but all six occupants escaped without injury.
The investigation
CENIPA investigators examined the engine components and discovered extensive internal damage, including the breakage of the camshaft, connecting rod bolts, and the crankshaft. The investigation focused on the cause of the crankshaft fracture, specifically looking at fatigue-related failure. The analysis compared the findings with international studies, such as those by the Australian Transport Safety Bureau (ATSB), and identified characteristics of stress-induced failure.
Crucially, the investigation revealed that the aircraft was operating outside of its certified weight limits. The pilot had used an outdated weight and balance form that listed an incorrect empty weight for the aircraft. Consequently, the aircraft departed with an excess weight of approximately 76kg above the manufacturer's maximum takeoff weight. The investigation concluded that the engine failure was likely caused by a crankshaft fracture due to fatigue, potentially triggered by high-stress operating conditions such as heavy takeoff weights and the use of unpaved or short runways.
Findings
- The aircraft was operating outside of its weight and balance limits.
- The pilot utilized an outdated weight and balance calculation form.
- The aircraft departed with approximately 76kg of excess weight.
- The engine failure was caused by the breakage of the crankshaft.
- The landing gear failure was caused by the high sink rate and misalignment during the emergency landing.