What happened
On September 19, 2006, an HB-350B helicopter, registration PT-HMM, departed from Aeródromo Pinto Martins in Fortaleza, Ceará, bound for Baturité. The aircraft was carrying a pilot and three passengers. Approximately ten minutes into the flight, while over the municipality of Guaiúmu, the pilot experienced a sudden loss of power accompanied by abnormal engine noise.
In response to the engine failure, the pilot initiated an autorotation procedure to perform an emergency landing in an unprepared area on a private property. During the landing flare, the tail rotor struck a tall tree, and the aircraft subsequently hit smaller trees before striking the ground and rolling 90 degrees to the right. The impact resulted in serious injuries for all four occupants, and the aircraft sustained damage so severe that it was considered a total loss.
The investigation
CENIPA's investigation focused on the mechanical failure and the maintenance environment of the aircraft. Investigators examined the engine and discovered that the G3 bearing was damaged. The investigation also revealed significant discrepancies in maintenance records; the operator could not provide flight hour logs for the period following a recent 100-hour inspection.
Furthermore, the investigation found that for the two months prior to the accident, the aircraft had been operating in the Ceará region without the support or supervision of a certified mechanic. The pilot, who was not a qualified mechanic, had been performing daily preventive maintenance and even frequent compressor washes using assistance from hangar personnel. The investigation also noted that the aircraft had been operating in a saline atmosphere, which can exacerbate corrosion and lubrication issues.
Findings
- Engine failure in flight caused by a damaged G3 bearing.
- Lack of professional maintenance supervision, as the pilot was performing maintenance tasks without being a qualified mechanic.
- Inadequate maintenance oversight, with the operator failing to ensure a certified mechanic was available to supervise the aircraft's operation in a coastal environment.
- Maintenance discrepancies, including missing flight hour records and inconsistencies in the execution of inspections by the maintenance workshops.
- Operational risks associated with the pilot performing engine compressor washes and daily inspections without proper technical training or oversight.