Australia:
A Wessex Mk31B helicopter suffered a ground resonance incident aboard Durance-class replenishment oiler HMAS Success (OR304), while the tanker was on passage to Darwin during Exercise Kangaroo 89. No personnel were injured, but the aircraft was subsequently written off due to damage. 8 Aug 1989
Operating at sea approximately 140 nautical miles (nm) northeast of Darwin, HMAS Success Flight’s Wessex helicopter was running on deck during an intermediate stop while conducting an intra-Task Group logistic support mission.
The aircraft had completed the initial portion of the mission, the transfer of passengers to and from nearby HMAS
Torrens to
Success, and was preparing for departure with an underslung load for delivery to USS
Oldendorf via Vertical Replenishment (VERTREP).
With the aircraft chocked and lashed on deck, the aircrewman had exited the aircraft to conduct cargo hook checks prior to commencing the underslung load portion of the mission.
As he re-embarked, the aircraft developed a violent padding side-to-side (rocking of the helicopter on its landing gear) that increased very rapidly to an uncontrollable degree. Recognising the onset of ground resonance, the pilot immediately attempted to shut down the engine by closing the high-pressure fuel cock.
One tie down lashing was seen to fall from the aircraft, allowing the aircraft to rapidly yaw to the right. The yaw collapsed the left-hand undercarriage radius arm, allowing all four rotor blades to strike the flight deck in turn. The aircraft came to rest approximately 30 degrees left wing down, and, once all violent motion had ceased, the three aircrew exited the aircraft unharmed.