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An AW-159 Wildcat maritime operation helicopter, which has been pulled from operations due to fatigue-based cracks in its vibration damper, is seen during an operation in February 2017. (provided by the South Korean Navy)

An abnormality detected in the AW-159 Wildcat maritime operation helicopter, which was used for patrol flights until November 2019, has been attributed to fatigue-based cracking in its vibration damper.

“On Nov. 23, 2019, damage occurred to the vibration damper on an AW-159 maritime operation helicopter. Flights by the model were suspended, and all units were examined with the manufacturer and experts to determine the cause and the possibility of the same phenomenon occurring again,” the South Korean Navy explained on Jan. 3.

“The investigation showed that the damage to the affected helicopter had occurred due to fatigue-based cracking,” it said.

The Navy planned to resume flights as of Jan. 3, 2020, for all seven of the helicopters besides the one in which the problem was observed. The damper connects the helicopter’s blades with its body and serves to absorb vibrations to prevent shuddering of the fuselage.

At around 12:10 pm on Nov. 23, 2019, a Wildcat made a precautionary landing at a military base after vibrations that occurred while it was performing operations. The design life for a damper is typically around 1,000 hours -- but the one in which the problem occurred had reportedly only been used for around 300. That same afternoon, the Navy issued an order to ground all eight Wildcat helicopters, including the one in which the vibration was observed.

In its explanation on Jan. 3, the Navy announced plans to continue investigating the matter with the manufacturer to determine why fatigue-based cracking occurred so soon within the operational period.

“No irregularities occurred with the fuselages of the other seven helicopters [besides the one in which the vibration occurred],” a Navy official said.

“Going forward, the Navy plans to intensify its safety inspections and operation rules for the model’s fuselage and operate them under rigorous flight safety measures,” the official added.

The AW-159 is a maritime operation helicopter used on destroyers and frigates. It includes state-of-the-art detection equipment and weapon capabilities for attacks on warships and submersibles, including the Spike anti-ship missile and the domestically produced Chung Sang Eo (Blue Shark) torpedo. In June 2016, the Navy acquired eight Wildcat helicopters developed with the UK and Italy in order to respond to the threat of North Korean submersibles, with an operational deployment on Feb. 1, 2017.

By Noh Ji-won, staff reporter

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