 On 31 May 2013, the Navy awarded Sikorsky a $435 million contract to deliver four prototype CH-53Ks for operational evaluation and mission testing; Sikorsky says the first two prototypes will examine structural flight loads while the third and fourth vehicles will focus on validating general performance, propulsion and avionics.On 1 October 2013, Sikorsky issued an $8.5 million contract to Kratos Defense & Security Solutions for the design and development of maintenance training systems for the CH-53K, including a full-fidelity Maintenance Training Device Suite (MTDS) and a Helicopter Emulation Maintenance Trainer (HEMT).The MTDS provides a realistic environment for training and evaluating maintainers of the CH-53K's various subsystems, such as avionics, electrical, and hydraulic systems.