What happened
On November 24, 2000, an AS350 B3 helicopter, registration PT-YCG, was performing a local flight at the Helibrás helipad in Itajubá, Minas Gerais. The flight was intended as a courtesy demonstration for a group of executives. The aircraft was carrying the pilot and five passengers.
Following engine start, the pilot began a scheduled hydraulic system check. During this procedure, the pilot moved the cyclic control longitudinally while simultaneously attempting to adjust a page on the Vehicle and Engine Multifunction Display (VEMD). During this sequence, the aircraft abruptly lifted off the ground without pilot command. The helicopter ascended several meters and entered an uncontrolled turn. In an attempt to avoid nearby aircraft on the ground, the pilot maneuvered the helicopter to the left, which caused the aircraft to tilt to the right, leading the main rotor to strike the ground. The helicopter overturned onto its cabin and fuselage.
The investigation
CENIPA investigators examined the aircraft and the operational circumstances. The AS350 B3 was a new aircraft with only 4 hours and 55 minutes of flight time. While maintenance records were up to date, the investigation focused on the state of the collective lever lock during the hydraulic test.
Tests conducted by the operator revealed that when hydraulic pressure is depleted during longitudinal cyclic movements, the collective tends to rise. Investigators also examined the pilot's actions, noting that the pilot had removed his hand from the collective to interact with the VEMD. The investigation also looked into the pilot's workload and the company's oversight regarding checklist adherence.
Findings
- The primary cause of the accident was the unintended movement of the collective lever, which occurred because the collective was either left unlocked or inadvertently unlocked during the hydraulic check.
- The pilot's high workload and fatigue contributed to a loss of situational awareness and difficulty concentrating on standard procedures.
- Excessive self-confidence and high levels of experience led the pilot to suppress or skip certain items on the pre-flight checklist.
- The company's supervision failed to recognize that the pilot's heavy workload and diverse responsibilities were leading to a habit of non-compliance with specific checklists.
- The aircraft sustained severe damage to the structure, engine, landing gear, rotors, transmission, and tail cone, though all six occupants escaped without injury.