HD Hyundai Heavy Industries (HD HHI) has been selected as the preferred bidder for the KSS-II (Type 214) mid-life upgrade (MLU) program by the Republic of Korea’s defense procurement agency, DAPA. The total value of the current MLU program is 500 billion KRW (approximately $360 million USD) and covers performance upgrades for the first three submarines acquired under the KSS-II Sohn Won-il–class acquisition program. The MLU plan was approved at the 165th Defense Project Promotion Committee meeting, held at the end of last year. Key systems slated for upgrade include the combat management system, towed array sonar, mine avoidance sonar, and a floating antenna system.
HD HHI has teamed up with LIG Nex1 for this MLU program. LIG Nex1 previously carried out the Performance Improvement Program (PIP) for the KSS-I Jangbogo-class (Type 209) submarines, successfully executing a comprehensive upgrade focused on sonar and combat system modernization. Notably, the PIP included the world’s first integration of a towed array sonar (TAS) onto a Type 209 submarine, significantly enhancing its long-range detection capabilities.
LIG Nex1 also overhauled the combat management system (CMS), replacing the aging ISUS-83 hardware with modern processing and storage components. These upgrades improved signal processing speed, enhanced target analysis accuracy, and enabled simultaneous torpedo engagements. Furthermore, the attack periscope was upgraded with infrared (IR) detection capabilities and higher image resolution, improving surveillance and target identification.
This marks the first time HD HHI will conduct a submarine MLU for the ROK Navy. Previously, the company overhauled the ROKS Yoon Bonggil, completing the work 35 days ahead of schedule and delivering the vessel to the Navy in June. Having demonstrated its efficiency and quality in that project, HD HHI is expected to deliver strong results in its first MLU effort. The current MLU targets the first three submarines of the KSS-II class, but follow-on upgrades for the remaining six units are anticipated, positioning HD HHI for potential future contracts under the program.
As the Republic of Korea Navy faces a decline in the number of skilled in-house technicians and the retirement of experienced technical personnel, there is a growing shift toward outsourcing maintenance and overhaul work through competitive bidding involving private-sector companies. Against this backdrop, HD HHI’s successful participation in the KSS-II MLU program enhances its credibility and positions the company as a strong contender in the evolving defense MRO market. This experience is expected to provide a significant advantage in future tenders, particularly as the Navy seeks capable partners to support the long-term sustainment of its fleet.
