The main improvements are new engines and cockpit layout.
The CH-53K will have over twice the lift capacity and radius of action of the CH-53E, and a wider cargo hold to allow it to carry a Humvee internally.
It supports maintenance training as well as remove-and-replace training for avionics systems, electrical systems, hydraulic systems, and other mechanical subsystems.
The HEMT uses a 3D virtual environment to support maintenance training scenarios.
The RH-53A and RH-53D were used by the United States Navy for minesweeping.
The CH-53D included a more powerful version of the General Electric T64 engine, used in all H-53 variants, and external fuel tanks.
Sikorsky proposed the S-80 design to the Marines in 1968.
The design features three 7,500 shp (5,590 k W) engines, new composite rotor blades, and a wider aircraft cabin than previous CH-53 variants. The USMC plans to receive 200 helicopters at a total cost of billion.
Israel's current CH-53 "Yasur" fleet is to remain operational until 2025.
On 1 October 2013, Sikorsky issued an .5 million contract to Kratos Defense & Security Solutions for the design and development of maintenance training systems for the CH-53K.
The CH-53A is equipped with two of the T64-GE-6 turboshaft engine and has a maximum gross weight of 46,000 lb (20,865 kg).
Variants of the original CH-53A Sea Stallion include the RH-53A/D, HH-53B/C, CH-53D, CH-53G, and MH-53H/J/M.As of 22 January 2016, the second of the four had been delivered.