Amy Butler/Stratford, Conn.

With the first CH-53K test article—a ground-test vehicle (GTV)—more than halfway complete, a longtime U.S. Marine Corps plan to overhaul its heavy-lift fleet is nearing developmental testing and production.

The technical hurdles in developing a new rotorcraft in the same footprint as the CH-53E it replaces, while more than doubling its load, appear to have been retired, says Col. Robert Pridgen, the Marines' CH-53K program manager. “There is nothing in front of us that is going to slow me down,” he tells Aviation Week. He acknowledges that flight-testing discoveries are possible.

One of the main challenges—developing a new split-torque gearbox—has already been overcome, and “that was no small mountain to climb,” he declares. With this design, three GE38-1B engines separately feed into the gearbox, allowing for a lighter design than the helicopter's predecessor, says Dave Zack, Sikorsky's CH-53K program manager.

The introduction of high-efficiency, composite main rotor blades, each with a swept anhedral tip, are also key to the CH-53K's improved performance. Zack says these massive structures are a generational advancement over the upgrades that Sikorsky added to the UH-60M's main blades. Moreover, these changes are integral to a design that will enable the Marines to carry far more cargo and operate off of amphibious ships.

Sikorsky won the $3 billion CH-53K development contract in April 2006 after submitting an unsolicited proposal; the Marine Corps was looking at options to upgrade its heavy-lift fleet comprised of CH-53D and E models. Technology maturation early in the program for the main rotor blades and gearbox was critical, as both were at a technology readiness level of 4 instead of 6, which is typically when the Pentagon moves forward with a design.

Sikorsky's development contract stands out among many Pentagon aircraft deals in that it is a cost-plus, incentive-fee arrangement. This means the Pentagon pays the cost of the work rather than capping the price—a strategy adopted to accommodate the immature technology early in the program. The Pentagon estimates it will cost $25.7 billion to buy 200 CH-53Ks. The figure includes roughly $6.8 billion in growth due largely to a quantity increase; the Marines originally expected to buy 156 rotorcraft.

With the design sound and fabrication of the first test articles underway, Sikorsky is gearing up its manufacturing and testing base. Together with its top industry partners, the team has invested $340 million in various facilities. Among them is a massive durability test center here at Sikorsky's plant as well as a systems integration laboratory (SIL) that incorporates production-representative hardware and software. Roughly 95% of the K's software has been loaded into the SIL.