What happened
On March 23, 2014, a Robinson R22 BETA, registration PP-SSP, departed from Helicentro Ribeirão Preto (SSUE) for a local flight. Approximately 13 minutes into the flight, while overflying the district of Bonfim Paulista, São Paulo, the aircraft experienced a sudden loss of control. The helicopter entered a steep, vertical descent with a high rate of sink, impacting a cornfield. The impact was violent, causing the aircraft to be destroyed and triggering a post-crash fire due to ruptured fuel tanks. The pilot and one passenger sustained two fatal injuries.
The investigation
CENIPA investigators examined the wreckage and flight dynamics, noting that the impact marks in the vegetation indicated a high-angle descent with almost no forward movement. The investigation found that the aircraft's systems and components showed no signs of mechanical failure prior to the accident. The aircraft was within weight and balance limits, and the pilot held valid commercial and flight instructor licenses, though recent operational proficiency in this specific model could not be verified. Investigators also noted that the flight controls for the passenger seat were found near the wreckage, suggesting they could have been removed for the flight.
Three hypotheses were evaluated regarding the loss of control: first, that the passenger may have applied improper controls during a demonstration; second, that the pilot may have attempted an out-of-ground-effect hover that resulted in a loss of rotor RPM; and third, that an improper recovery attempt during an autorotation led to a rotor stall. The investigation concluded that the high rate of descent was inconsistent with a normal flight or a standard autorotation.
Findings
- Inadequate control inputs may have led to a vortex ring state or a loss of control that could not be recovered.
- A lack of verifiable recent experience in the R22 BETA may have affected the pilot's psychomotor responses required for emergency recovery.
- The presence of a passenger with an interest in aviation may have led to the pilot allowing the passenger to manipulate the controls, potentially inducing a loss of control.