What happened
On a summer evening in August 2013, a Kamov Ka-32A11BC helicopter, registered as C-GKHL and operated by VIH Helicopters Ltd., was engaged in aerial firefighting near Bella Coola, British Columbia. The aircraft was utilizing a long line and water bucket attached to its external load hook to collect water from a high-altitude mountain lake.
Shortly after lifting a load of water, the crew experienced a sudden loud bang, followed by intense grinding and howling noises. The aircraft began to vibrate violently, making it impossible for the crew to read the cockpit instruments. In response to the instability, the pilot not flying released the external water bucket and line. The pilot flying directed the aircraft toward land to attempt an emergency landing.
During the descent, the crew struggled to maintain a consistent heading due to the severe shaking. The helicopter made contact with the ground while drifting sideways to the right, despite the pilot applying near-full left cyclic input. Upon impact, the aircraft bounced and rolled onto its right side, causing the main rotor blades to strike the ground and break. The crew successfully shut down the engines and evacuated the aircraft. There were no fatalities, though the crew sustained minor injuries.
The investigation
The investigation focused on the mechanical failure that occurred during the water collection process. Investigators examined the sudden onset of noise and vibration, the behavior of the aircraft during the emergency descent, and the activation of the 406 MHz emergency locator transmitter upon touchdown. The investigation also looked into the mechanical state of the engines following the reported loud bang and grinding sounds.