Powered ground tests of the Sikorsky CH-53K, the U.S. Marine Corps’ future heavy-lift helicopter, are now well under way at the company’s West Palm Beach, Florida facility in the run-up to first flight later this year. The first ground-test vehicle (GTV1) started systems testing in late April, about a week before the first flying article was rolled out on May 5. Operational service of the mostly composite helicopter, which has been dubbed the “King Stallion,” is expected in 2019.

“The rollout of the CH-53K helicopter introduces a new era in Marine Corps aviation,” said Sikorsky president Mick Maurer. “The clean-sheet CH-53K will effectively triple the external load carrying capacity of the CH-53E aircraft–to more than 27,000 pounds, over a mission radius of 110 nautical miles.

“With its 88,000-pound maximum gross weight, powerful new engines, lightweight composite structure, new rotor blades and fly-by-wire flight controls, the CH-53K will have the means to move troops and equipment from ship to shore, and to higher altitude terrain, more quickly and effectively than ever before.”

Three 7,500-shp GE Aviation T408 engines power the helicopter, offering 57-percent more horsepower and 20-percent lower specific fuel consumption compared to the CH-53E’s GE T64 turboshaft. To convert the extra engine power into torque and shaft horsepower within a similarly sized main gearbox, Sikorsky developed a new transmission system that transfers that power to the “largest and most technologically advanced” main rotor blade that Sikorsky has ever produced. Measuring 35 feet in span length and almost three feet in chord width, the all-composite blade has 12 percent more surface area than the blade on the CH-53E, the King Stallion’s predecessor that was produced in the 1980s.

All Digital

Thanks to an airframe built from strong, lightweight composite materials, the CH-53K retains the same external footprint as its predecessor–a required specification for the helicopter to fit on existing U.S. Navy ship elevators–but has a cabin that is 13 inches wider. On the flight deck, a Rockwell Collins digital glass cockpit governs a fly-by-wire flight control system developed by Sikorsky (Hall 1, Chalet 15 and Outdoor Exhibit 3/4), UTC Aerospace Systems, Eaton and BAE Systems.

According to Sikorsky, the CH-53K is one of the first all-digital helicopters designed. This approach enabled the company to assemble the aircraft inside a 3-D virtual reality lab at its Stratford, Connecticut headquarters before any metal was cut or composites were laid out. “Our ‘build before you build’ approach allowed our engineers to work ‘inside’ the helicopter,” said Maurer, “to verify assembly designs and correct issues long before discovery and expensive rework on the assembly line.”

Meanwhile, powered ground tests of GTV1 will help to shake out any issues with the CH-53K’s aircraft systems, including rotors, drive, electrical, hydraulic, avionics and flight controls. GTV1 will log some 250 hours of powered ground tests before the CH-53K’s first flight later this year, which will kick off a three-year flight test program. The ground-test vehicle is bolted to the ground at a remote testing area within Sikorsky’s West Palm Beach, Florida facility and will ultimately log a total of 900 hours of tests by the end of 2016, after which the airframe will be shipped to Naval Air Station China Lake in California for live weapons testing. There it will be shot with an array or ordinances to see how the airframe holds up.

Currently, the USMC has nine CH-53Ks under contract: four engineering development model flight vehicles, which are currently being built on the production line in West Palm Beach; GTV1; a static article; a fatigue article; and two recently added system demonstration flight-test articles. The USMC intends to order at least 200 CH-53Ks and set up eight operational squadrons and one training squadron.