What happened
On January 30, 2008, a Bell 206B helicopter, registration PT-HEO, departed from the Helisul IV helipad in Foz do Iguaçu, Brazil, for a sightseeing flight. The aircraft was carrying one pilot and four passengers. Approximately 450 meters after takeoff, the engine suffered a failure. The pilot responded by lowering the collective and banking to the left to execute an emergency landing in a nearby cornfield.
The landing was abrupt. The impact caused the main rotor to flex excessively and strike the tail cone, resulting in the rupture of the tail rotor drive shaft. The forward lower transparencies of the aircraft were also broken due to contact with vegetation. Despite the impact, the pilot and all four passengers were uninjured.
The investigation
CENIPA investigators examined the engine components and found that a fatigue crack had developed in a blade of the third-stage compressor, which led to the engine failure. The investigation revealed that the fatigue process was accelerated by the deterioration of blades in the third, fourth, and sixth stages due to pitting corrosion, particularly on the leading edges and the concave surfaces near the blade roots. Evidence of sanding was found on several blades, suggesting attempts to manually remove these pits.
Furthermore, the investigation identified a lack of documented maintenance regarding compressor washes. There were no records indicating the frequency, methods, or products used for these procedures, which is required by the maintenance manual. The investigation also noted organizational deficiencies within the operator, including inadequate management of crew training, lack of centralized safety documentation at the operational base, and insufficient oversight of maintenance and safety programs.
Findings
- Engine failure caused by a fatigue crack in a third-stage compressor blade.
- Corrosion-induced pitting on compressor blades facilitated the fatigue process.
- Lack of controlled records for compressor washing procedures.
- Inadequate management of safety resources, including inconsistent crew training oversight and poor maintenance documentation control.
- Possible improper execution of the autorotation procedure, leading to an excessively hard landing.