What happened
On August 1, 2006, an Agusta Bell AB-412, registration D-HAFV, was engaged in firefighting operations near Cortes de la Frontera, Málaga. After completing water drops, the pilot was instructed to land to collect a firefighting brigade (BRICA) and stow the Bambi Bucket external load into a side basket.
The pilot landed on a steep, irregular hillside characterized by partially buried rocks. While ground personnel were attempting to secure the bucket, the helicopter began to experience intense, low-frequency vertical vibrations. Unable to stabilize the aircraft and facing an imminent risk of rollover, the pilot initiated a vertical ascent. During this sudden movement, a member of the ground crew, who was passing near the bucket cables, was caught by the lines and lifted several meters into the air before falling to the ground. The individual sustained serious injuries.
The investigation
The CIAIAC investigation focused on the stability of the aircraft during the landing and takeoff phases. The investigation established that several factors contributed to the aircraft's instability on the ground, including the steep slope, the uneven terrain, the fact that the force trim system was deactivated, and the collective lever not being fully lowered.
Furthermore, the investigators examined the cargo release system. The 'CARGO REL' switch was in the 'OFF' position, meaning the electrical release mechanism was inoperable. This would have forced the pilot to use a mechanical release pedal, requiring him to momentarily relinquish yaw control at a critical moment.
Findings
- The helicopter landed on irregular terrain that did not provide a stable base for the skids.
- The pilot did not correctly follow the standard post-landing procedures.
- The electrical cargo release system was not armed, preventing a quick release of the bucket.
- The positioning of the ground crew during the bucket retrieval process left them without a clear escape route.
- The sudden movement of the Bambi Bucket during the emergency ascent likely induced further instability in the aircraft.
Safety action
- REC 17/08: It is recommended that the operator, FAASA, include specific procedures in its Operations Manual for working with Bambi Buckets to ensure the electrical cargo release system is operational during all takeoffs and landings.