What happened
On 13 September 2025, the pilot of a Eurocopter AS 350 B2 helicopter was conducting aerial fire suppression operations over an active grass fire in regional North Queensland. The helicopter was about 500 ft above ground level, with about 50 kt airspeed and a laden water bucket. At about 1220 local time, the helicopter completed a turn and the pilot reported feeling a jolt and observed, via an external mirror, the water bucket and attached line falling from the helicopter. The bucket and line impacted the ground causing significant damage to the bucket but no other damage or injuries.
The pilot recalled that, at the time the bucket released from the helicopter, their hands were clear of the cyclic cargo release button and manual release handle. The pilot landed the helicopter immediately and advised the helicopter operator of the incident.
Shortly after landing the pilot conducted a post-flight inspection. There was no damage to the helicopter, however the pilot was able to replicate the cargo hook unintentionally opening by moving the assembly in certain directions (Figure 1 shows the type of cargo hook fitted). The pilot later determined that the manual release cable had been incorrectly rigged. They observed a loop in the manual release cable prior to the cable entering the cargo hook assembly that caused the cable to tension and triggered the opening of the cargo hook.
Figure 1: Cargo hook used by the operator’s AS350
Source: Onboard Systems, annotated by the ATSB
Safety message
The uncommanded release of an underslung load has the potential for fatal consequences, damage to property and the load itself. Another occurrence of an underslung load being released without pilot input from a Eurocopter AS 350 helicopter as a result of the incorrect rigging of the cargo hook manual release cable has been detailed by the ATSB (AB‑2024‑033).
Although the rigging mechanism of the manual release cargo hook cable is not visible to the pilot during a pre-flight inspection, pilots intending to conduct underslung operations are encouraged to check for correct rigging and, if possible, simulate the full range of cargo hook movement prior to flight to observe any abnormalities.
About this report
Decisions regarding whether to conduct an investigation, and the scope of an investigation, are based on many factors, including the level of safety benefit likely to be obtained from an investigation. For this occurrence, no investigation has been conducted and the ATSB did not verify the accuracy of the information. A brief description has been written using information supplied in the notification and any follow-up information in order to produce a short summary report, and allow for greater industry awareness of potential safety issues and possible safety actions.