What happened
On 22 January 2022, a UH-1H helicopter, registration ZS-HHJ, was engaged in aerial firefighting operations at the Silver Mine Nature Reserve in the Western Cape. While attempting to refill a Bambi bucket from a shallow dam, the pilot was unable to fully submerge the bucket due to low water levels. This caused the suspension cables to become entangled on the aircraft's tail rotor guard, resulting in the bucket swinging horizontally during lift-off.
Seeking to untangle the equipment, the pilot transitioned to a nearby sports field. During the descent over a ridge, the aircraft encountered a strong updraft. This turbulence caused the bucket to swing out of the pilot's view in the monitoring mirror. Shortly after, a physical impact was felt on the fuselage. Upon landing and conducting a post-flight inspection, the pilot discovered that the bucket remained attached to the tail rotor guard and that the tail rotor blades had sustained damage from contact with the bucket.
The investigation
SACAA AIID examined the operational procedures and the aircraft's maintenance history. The investigation confirmed the pilot held a valid Commercial Pilot Licence and the aircraft had a current Certificate of Airworthiness. However, investigators noted that the operator had removed the bucket and sling equipment before investigators could examine them, which hindered the investigation process.
Findings
- The primary cause of the incident was the Bambi bucket becoming entangled on the tail rotor guard and subsequently striking the tail rotor blades after it moved out of the pilot's visual field.
- The operator's manual lacked specific procedures for managing water refills from shallow sources or mitigation steps for snagged cables.
- The manual also lacked necessary tail rotor clearance calculations required by the manufacturer's guidelines.
- The pilot did not perform an orbital observation to verify the status of the load once it disappeared from the mirror view.