Lockheed Martin is cleared to begin assembling the first two production versions of the Sikorsky CH-53K King Stallion under a $304 million contract awarded by the US Navy last week.

Sikorsky will deliver two of the heavy-lift rotorcraft with a maximum gross takeoff weight of 39,900kg (88,000lb) to the USMC in 2020 under the low-rate initial production Lot 1 contract. The Pentagon approved the King Stallion’s production and deployment phase in April.

The USMC plans to replac an aging fleet of CH-53E Super Stallions with 200 King Stallions, with four early production aircraft set for delivery this year. The US Navy has estimated the the aircraft's average unit price at about $87 million, if all 200 CH-53Ks are ordered.

The CH-53K remains similar in shape to the CH-53E, but represents a full transformation of the heavylift helicopter. The new version features three GE Aviation T408 engines, a new transmission, new rotor blades, a composite fuselage and new avionics.

Meanwhile, Sikorsky is eyeing the German Air Force’s “Schwerer Transporthubschrauber” (STH) heavy-lift helicopter programme, which would replac Germany’s fleet of 81 CH-53GA/GS helicopters originally delivered in the 1970s. The request for proposals is scheduled for release in mid-2018, with a contract award in 2019. Deliveries would begin in 2023 when Germany begins to retire the CH-53GA/GS fleet.

Sikorsky’s King Stallion, still in development with the USMC, is primed for a head-to-head competition with Boeing’s CH-47 Chinook.