What happened
On September 6, 2022, a Robinson R44 II helicopter, registration PR-WGS, was performing a private flight from Fazenda Lagoa Nova to the Minervino Pinheiro Football Stadium in Monte Santo, Bahia. The aircraft was carrying a pilot and two passengers.
As the pilot was executing a traffic pattern for landing, the aircraft experienced a loss of control. Unable to recover the flight attitude, the pilot performed an emergency landing in an open field near Avenida Walter Calload. During the final moments of the landing, the main rotor blades struck an embankment, causing the helicopter to spin and come to a halt. The aircraft sustained substantial damage, including the destruction of the main rotor blades and windshield, as well as damage to the tail cone, tail rotor, and skids. All three occupants escaped the crash uninjured.
The investigation
CENIPA investigators examined the aircraft's maintenance history, the pilot's experience, and the environmental conditions at the time of the accident. The investigation confirmed that the pilot was properly licensed and qualified, and the aircraft's airworthiness documentation was up to date. Meteorological conditions were favorable for VFR flight, with visibility exceeding 10 km.
Technical analysis of the engine revealed a loss of compression in five cylinders. Investigators also looked into the pilot's situational awareness, noting that a request from a passenger to view a specific location on the ground may have distracted the pilot during a critical phase of flight.
Findings
- The loss of control was likely associated with the aircraft's speed dropping below its translational lift velocity.
- A momentary loss of situational awareness regarding wind direction and airspeed may have occurred during a 180-degree right-hand turn.
- The pilot's attempt to correct the descent by applying collective input likely caused a drop in rotor RPM, a condition potentially aggravated by reduced engine power due to cylinder compression loss.
- Inadequate use of anti-torque pedals during the collective application may have contributed to the unrecoverable state of the aircraft.
- Maintenance discrepancies were noted in the engine cylinders, though it could not be determined if these were linked to the execution of Service Instruction 1191.
Safety action
CENIPA recommended that the National Civil Aviation Agency (ANAC) disseminate the lessons learned from this investigation to Civil Aviation Instruction Centers (CIAC). The goal is to alert Robinson R44 pilots to the risks outlined in Robinson Helicopter Company's Safety Notice 34 (SN-34) regarding the prevention of loss of translational lift.