for the two frigates. Unlike the Australians, the New Zealand contract specified new-build helicopters. Kaman Aerospace loaned four SH-2F Seasprites to the RNZN while the new helicopters were constructed: the SH-2Fs operated from February 1998 to August 2001, when the first two SH-2Gs were accepted into service. In 2006, the RNZN fitted two Mini Typhoons for each of its Anzac-class frigates. In 2007, Te Kaha began undergoing a series of major upgrades as part of the four-stage Platform Systems Upgrade (PSU), planning for which started in 2004. The four areas of modification under the PSU were improved stability and compartment configuration changes, overhaul of the propulsion system, installation of a new Integrated Platform Management System (IPMS), and upgrades to onboard environmental control. The stability upgrades were to accommodate predicted increases in displacement as updated equipment was installed on the ships. As part of the modification, the ships' quarterdecks were partially enclosed, creating space for a gymnasium and improved laundry facilities. Propulsion changes are primarily focused on replacing the TB83 diesel engines with the TB93, providing an additional and higher speeds during diesel-only sailing. The IPMS replacement is prompted by the perceived obsolescence of the current system by 2013; as of 2009, tendering for the new system was underway. The environmental control upgrade is intended to improve personnel comfort during deployments to South East Asia, the Middle East, or similar climates, and will use more environmentally friendly products. Each stage of the upgrade is organised to occur simultaneously with ship maintenance dockings, with the first two upgrades being installed during each ship's major maintenance docking in 2009 and 2010 respectively, then the other two upgrades during the next docking in the 2011–2012 period. A series of austere upgrades were approved on 14 April 2014, at an original contract cost of NZ 446m under the ANZAC Frigate Systems Upgrade (FSU) programme. These include the replacement of the existing combat management system, with a system modelled on that of the RCN Halifax frigates awarded to Lockheed Martin, The British Sea Ceptor anti-air missile replaced the Sea Sparrow on 27 May 2014. Other changes included the Norwegian Penguin Mk 2 Mod 7 for the Seasprite helicopters and the fitting of a Sea Sentor Surface Ship Torpedo Defence, or SSTD system, as well as MASS (Multi Ammunition Softkill System). A new inertial navigation positioning system (Northrop Grumman) and navigation radar and SharpEye™ surveillance radars with