The Sikorsky CH-53K King Stallion helicopter has flexed its muscles, lifting a 27,000-lb (12,245-kg) payload at Sikorsky's Development Flight Test Center in West Palm Beach, Florida. The demonstration flight, which saw the aircraft hover while carrying a little less than the weight of a double-decker bus, was part of the development and testing program for the transport helicopter slated to enter service with the United State Marine Corps by the end of the decade.

For the test flight, the King Stallion had to lift its payload to an altitude of 100 ft (30 m). This was to negate what is called the "out of ground effect" (OGE). When a helicopter is flying close to the ground, the downwash from the rotors forms a sort of air cushion under the aircraft that helps support it. To eliminate this, the CH-53K had to fly higher than its main rotor's diameter of 79 ft (24 m). According to Lockheed Martin, which bought Sikorsky last year, this produces the most stressful of power lift conditions for the vehicle.

The fly-by-wire CH-53K King Stallion heavy-lift helicopter is being developed for the US Marine Corps and will be the heaviest helicopter in the US military inventory, capable of carrying a crew of five and up to 37 to 55 troops. In addition to hits heavy lift capability, it has enough internal space to carry a Humvee and has a new external cargo system. So far, its prototypes have reached speeds of over 140 kts (161 mph, 259 km/h) and have previously lifted loads of 20,000 lb (9,072 kg).

A third CH-53K King Stallion helicopter has been added to the program to speed up development and testing, and a fourth is scheduled to join it later this year. One of the prototypes will carry a 27,000-lb external load over 110 nautical miles (127 mi/204 km) at 91.5° F (33° C) at an altitude of 3,000 ft (914 m) to fulfill the US Navy operational requirement in "high hot" conditions.

Up to 200 of the Stallions are scheduled for delivery with the first to enter service with the Marines in 2019.

"This 27,000 pound external lift is yet another key milestone for the program," says Dr Michael Torok, Sikorsky Vice President, CH-53K Programs. "The King Stallion achieved this external lift with ease, and we are on track to successfully complete the initial operational assessment this year."