What happened
On October 8, 2020, an AS3CO B2 helicopter, registration PR-MJZ, was performing a flight from Corumbá to Poconé in the state of Mato Grosso do Sul, Brazil. The aircraft, operated by the Ministry of Justice and National Public Security Secretariat, was carrying two pilots and one tactical operator.
Approximately five minutes before reaching its destination, the aircraft experienced a loss of main rotor RPM. The crew heard the low rotor RPM aural warning and attempted to perform a low-altitude autorotation. However, the aircraft collided with the ground at a high rate of descent. The impact caused substantial damage to the airframe, including the destruction of the skids, stabilizers, tail boom, and rotor components. The pilot sustained serious injuries and passed away several days after the accident, while the second pilot and the tactical operator sustained serious and minor injuries, respectively.
The investigation
CENIPA's investigation focused on the powerplant failure and the operational decisions made by the crew. Investigators examined the engine, specifically the Arriel 1D1, and identified internal corrosion and partial clogging of the filter within the Fuel Control Unit (FCU).
The investigation also reviewed the meteorological conditions, noting that visibility was reduced due to smoke in the region. The investigators analyzed the crew's flight path, finding that the pilot had descended to approximately 200 feet above the ground in an attempt to maintain visual flight conditions. The investigation also looked into the maintenance history, noting that a previous maintenance task on the engine's anticipator had occurred 50 flight hours prior, but did not provide access to the contaminated area of the FCU.
Findings
- Internal corrosion and clogging within the Fuel Control Unit (FCU) contributed to the powerplant malfunction.
- The crew's decision to continue VFR flight under degraded visibility was a significant contributing factor, as it led to a reduction in flight altitude.
- The low flight altitude (approximately 200 feet) significantly reduced the available reaction time to manage the emergency and execute proper procedures.
- A lack of standardized training and manuals for Special Public Aviation Operations contributed to potential inadequacies in crew performance and risk assessment.
- The absence of Crew Resource Management (CRM) training was identified as a factor that may have hindered efficient resource use during the emergency.