What happened
On March 9, 2010, an Embraer 712 (registration PT-NYV) was conducting a local instructional flight from Aeródromo Carlos Prates in Belo Horizonte, Brazil. During the climb phase, following a touch-and-go maneuver on runway 27, the crew experienced abnormal vibrations. The instructor took control and immediately initiated a return to the airfield to land on runway 09.
During the final approach, the vibration intensified, prompting the instructor to shut down the engine near the runway threshold. As the aircraft decelerated on the runway, the pilot intentionally steered the aircraft toward the left side of the pavement. The aircraft traveled approximately 250 meters—covering 100 meters of the runway and 150 meters of the adjacent grass area—before the nose gear collapsed. The aircraft sustained substantial damage to the wings, engine, propeller, and landing gear. One crew member sustained light injuries, while the other remained uninjured.
The investigation
CENIPA investigators examined the propeller and discovered that one blade was missing its tip. Laboratory analysis conducted at the Institute of Aeronautics and Space (IAE) revealed that the failure was caused by a subcritical crack propagation. Microscopic examination identified fatigue striations and evidence of intergranular corrosion on the blade's underside.
Investigators also reviewed maintenance records and found that there was no evidence the operator had performed the specific inspections recommended in Sensenich Propeller Inc. Service Bulletin (SB) R15A. This bulletin required operators to inspect fixed-pitch metal propellers for signs of corrosion, such as bubbling paint or white powder, every 100 flight hours or annually.
Furthermore, the investigation analyzed the pilot's decision-making. Although the aircraft was traveling at a speed between 70 and 85 knots—slightly above the recommended 70-knot landing speed—the instructor chose to exit the runway prematurely. The investigation determined that the instructor's decision was driven by high anxiety and fear that the aircraft would not stop in time to avoid the steep 10-to-30-meter declines located at the end of the runways.
Findings
- The propeller blade tip failed due to a fatigue fracture initiated by intergranular corrosion.
- There was no documented proof that the recommended inspections from SB R15A had been performed during the most recent 100-hour or annual inspections.
- The pilot's decision-making was influenced by high levels of anxiety regarding the potential for a runway overrun into the terrain drop-off.
- Management supervision, pilot judgment, and the decision-making process were identified as contributing factors.