First CH-53K prototype prepares for ground tests

The first prototype aircraft of the CH-53K heavy lift helicopter being developed by Sikorsky for the US Marine Corps (USMC) has been delivered to the flight test team. The prototype – the Ground Test Vehicle (GTV) – will now undergo preparation and testing for hundreds of hours of powered ground checks ahead of the four follow-on flight test helicopters that will take to the skies during 2014-15.

According to Sikorsky, flight test engineers will spend the coming months performing preliminary acceptance tests that include calibrating the GTV's fuel system and attaching measuring devices at more than 1,300 test locations on the aircraft to record temperature, aerodynamic loads, pressure and vibrations. By mid 2013, the GTV will be attached to a specially built outdoor platform to hold the aircraft in place when its three engines are powered on - a process known as a light-off. Initial light-off test events will be performed without rotor blades, followed by more rigorous tests with the blades attached.

Though designed to the same footprint size as the CH-53E Super Stallion helicopters they will begin to replace in 2019, CH-53K helicopters will triple the external load carrying capacity to more than 27,000 pounds over 110 nautical miles under high hot ambient conditions. Technology enablers for increased lift include 7,500-shaft-horsepower GE38-1B engines; a split torque transmission design that more efficiently distributes engine power to the main rotors; fourth-generation composite rotor blades for enhanced lift; and a composite airframe structure.

Michael Torok, Sikorsky's CH-53K program vice president, said: ‘The primary purpose of the GTV is to shake out the CH-53K helicopter's dynamic systems by thoroughly testing and measuring the performance of the rotor blades, transmission, and engines while the aircraft is tied to the ground. Extensive ground-based flight checks with Sikorsky and NAVAIR test pilots at the cockpit controls will confirm whether these dynamic systems, as well as hydraulic, electrical, and avionics systems, can meet the requirements established by the marines for their next-generation heavy lift helicopter.’

Col. Robert Pridgen, program manager for the heavy lift helicopters, added: ‘This is an important point of transition for the CH-53K programme. I am encouraged by the initial results of our testing at the component and subsystem level. Now we bring it all together. The GTV is our first dynamic system-level integration of those same components. We are looking forward to the sights and sounds these next heavy lifters will bring to the marine corps.’

Sikorsky is designing, building and testing the GTV and the four flight aircraft, designated Engineering Development Models, as part of a $3.5 billion System Development and Demonstration contract. Two additional ground test articles are undergoing airframe structural testing at Sikorsky's main manufacturing plant in Stratford, as part of the same contract. The aircraft's major fuselage sections are supplied by Aurora Flight Sciences, ITT Excelis, GKN Aerospace and Spirit Aerosystems.