 The "Yavuz"-class frigates have adopted the CODAD propulsion method with 4 MTU 20V Diesel engines, which require a substantial amount of maintenance.There were also questions over the selection of the Swiss manufactured Sea Zenith, an advanced CIWS system that was never previously used on any naval platform, but there have been no negative reports regarding the system's performance from the Turkish Navy.The later Track IIA frigates have incorporated major improvements including the CODOG propulsion method with two MTU 16V diesel engines and two LM2500-30 gas turbines, a greater displacement of 3,350 tons (full load) and the replacement of the older Mk-29 Sea Sparrow launcher with the Mk-41 Mod 8 VLS.