The South Korean Army’s supply of Surion helicopters has been suspended. According to the Defense Acquisition Program Administration they failed a critical airworthiness test, to withstand the cold. They plan to redesign the failed systems and redo the test within a year and a half, reports Defense News.

The Surion helicopters, codenamed KUH-1, was produced by Korea Aerospace Industries and Airbus Helicopters. The order was to replace their aging UH-1Hs and 500MDs.