What happened
On February 2, 2009, at approximately 1:45 PM, a Bell OH-5able helicopter, registration HI-855, crashed in the Los Calimetes area of Elías Piña, Dominican Republic. The aircraft was performing agricultural spraying operations over an avocado plantation. After completing eight successful flights that day, the pilot began the ninth mission. Approximately five minutes into the flight, while flying at an altitude of roughly 4,300 feet MSL (about 100 feet above the surface), the aircraft lost control. The helicopter struck avocado trees before hitting a 45-degree slope, where it rolled several times before coming to rest against a tree. The two occupants—the pilot and a passenger—sustained minor injuries.
The investigation
The CIAA investigation examined the aircraft's mechanical condition, the pilot's credentials, and the environmental factors at the time of the accident. Investigators found that the engine had been sent to Rolls Royce in the United States for laboratory testing, which confirmed that the turbine operated normally under all test regimes. The investigation also revealed that the spraying equipment had been removed from the aircraft by the operator before investigators arrived, an action intended to obscure evidence of the spraying operation. Additionally, it was discovered that the pilot's medical certificate had expired in October 2008, though it was renewed the day after the accident.
Findings
- The primary cause of the accident was the pilot's failure to follow basic operational safety rules, specifically regarding specialized agricultural flight maneuvers.
- The aircraft experienced Loss of Tail Rotor Effectiveness (LTE). This was driven by high density altitude (4,300 feet), the weight of the aircraft following refueling (45 gallons of fuel) and the addition of 100 gallons of agricultural liquid, and prevailing winds. These factors increased torque requirements, making it impossible to maintain anti-torque control.
- The pilot lacked the specific training and authorization required for aerial spraying operations.
- The terrain, characterized by steep slopes and dense vegetation, prevented a successful emergency autorotation attempt due to the low altitude and low airspeed at the time of the loss of control.