Unballasted sling causes tail rotor failure in Airbus AS350 accident

Casualties unknown • Thiézac, FR

An Airbus AS350-B3e sustained significant damage after an unballasted metal sling wrapped around its tail rotor during an external load operation.

What happened

On 30 October 2020, an Airbus AS350-B3e, registration F-HLXO, was performing external load sling operations near Thiézac, France. The mission involved transporting heavy tanks and bags using a 10-meter metal cable and a 2-meter textile extender.

During the initial phase of the mission, the pilot delivered a load to a set-down zone. Upon arrival, a ground agent found that the textile sling straps were too short, keeping the hook under tension and preventing it from being opened. To resolve the issue, the crew decided to uncouple the textile sling from the metal sling. This action removed the 15 kg ballast that had been attached to the end of the metal cable.

As the pilot returned to the loading zone, the aircraft descended and gained speed. While flying at approximately 87 knots—exceeding the recommended safety speed (Vy) for unballasted slings—the metal sling became wrapped around the tail boom and the tail rotor. The pilot reported hearing a grating sound and losing effective pedal control, but was able to perform an emergency landing near the take-off zone.

The investigation

The BEA examined flight data from the Helisafe and Vision 1000 computers, which allowed investigators to synchronize cockpit audio with flight parameters. This confirmed the exact moment the sling interfered with the tail rotor. Because the aircraft was removed from the site by the operator before the BEA arrived, the investigation relied on photographs to assess the damage.

Physical evidence showed that the metal sling had wrapped around the tail rotor blades, the tail gearbox, the horizontal stabilizer, and the tail fin. The investigation also reviewed the experience of the pilot, who had over 1,300 flight hours, and the procedures used by the ground personnel.

Probable cause

The accident was caused by the metal sling wrapping around the tail rotor due to excessive airspeed during descent while the sling was unballasted. Contributing factors included the decision to fly without the required 15 kg ballast and the failure to properly check the length of the load straps during preparation.

Frequently asked questions

What happened in the 2020-10-30 Airbus AS350-B3e accident near Thiézac, FR?

An Airbus AS350-B3e sustained significant damage after an unballasted metal sling wrapped around its tail rotor during an external load operation.

What aircraft was involved and where did it happen?

The accident on 2020-10-30 involved a Airbus AS350-B3e, registration F-HLXO, at Thiézac, FR.

What was the probable cause of the accident?

The accident was caused by the metal sling wrapping around the tail rotor due to excessive airspeed during descent while the sling was unballasted. Contributing factors included the decision to fly without the required 15 kg ballast and the failure to properly check the length of the load straps during preparation.

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