What happened
On September 21, 2024, a private Bell 206B helicopter, registration N206BH, was conducting a VFR flight from La Caya to Cacique, Monción, in the Santiago Rodríguez province of the Dominican Republic. The flight originated from the rooftop of a residence in Cacique.
During the takeoff phase, the aircraft experienced a sudden and total loss of engine power. The pilot reported hearing an audible bang immediately preceding the power loss. In response to the emergency, the pilot performed an autorotative landing on a nearby cliffside. Upon impact with the terrain, the helicopter struck the ground and rolled down a slope, eventually coming to rest upside down in dense vegetation. Following the impact, a small fire was observed in the engine exhaust duct, which the pilot extinguished using the onboard fire extinguisher. Both occupants of the aircraft survived the accident without injury, though the aircraft was destroyed.
The investigation
The CIAA investigation focused on the engine's performance and fuel system integrity. Investigators examined the Rolls Royce 250-C20J engine while it was still installed in the aircraft. The inspection included checks of the engine mounts, exhaust collector, fuel control unit (FCU), and power turbine components.
While the fuel in the supply line and the airframe fuel filter appeared clean and free of water, investigators discovered an unidentified soft matter within the airframe filter. Crucially, upon disassembling the fuel injector, the team found that the injector filter was completely clogged with a semi-transparent gel.
Findings
- The investigation found no evidence of mechanical failure or internal engine malfunction.
- The primary cause of the engine shutdown was fuel starvation caused by a restriction in fuel flow.
- This restriction was produced by a semi-transparent gel that had accumulated and completely obstructed the fuel injector filter.