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Monday, August 1, 2011

First Sikorsky CH-53K Enters Final Assembly

By Douglas Nelms

Final assembly of the first CH-53K is taking place at Sikorsky’s new Florida Assembly and Flight Operations (FAFO) center in West Palm Beach.  Sikorsky

Sikorsky has begun final assembly of the first CH-53K prototype test aircraft, with the sponsons and main rotor pylon now attached to the basic airframe. As of mid-July, all landing gears had successfully completed a trial fit check and were ready for final installation. The company says the program has entered the assembly and test phase with all the program milestones on track and with the key performance parameters (KPPs) and technical performance measures (TPMs) being met.

This first of seven prototypes is the ground test vehicle (GTV) and was started on Jan. 1, 2011. It is scheduled to start ground-flight testing early next year. The CH-53K will replace the CH-53E currently in operation with the U.S. Marine Corps. Assembly of the GTV and four other prototypes, or System Development and Demonstration (SDD) aircraft, will be at Sikorsky’s new Florida Assembly and Flight Operations (FAFO) facility in West Palm Beach. Two of the seven test aircraft will be assembled in Stratford, Conn.

The second aircraft will be the static test article, used to conduct structural load test and analysis. This will be followed by four engineering development models (EDMs)—labeled simply EDM One, Two, Three and Four, according to David Zack, CH-53K program manager.

Sikorsky will instrument EDM1 to support airframe structure and dynamics testing, and the first flight aircraft. “This will see that all the systems prove out and will be fully instrumented to gain data to prove that it is flight worthy,” Zack said. EDM2 will be used for aircraft handling qualities, performance and propulsion testing, with EDM3 for structural analysis and avionics testing and EDM4 for avionics and mission system testing. All four EDM prototypes will be flight capable. First flight is scheduled for the second quarter of FY14. The seventh test aircraft is the fatigue test article and will be assembled in Stratford. The eighth will be the first of the low rate initial production (LRIP) aircraft, starting after the Milestone C decision scheduled for FY15.

Greg Hames, CH-53K deputy program manager, noted that the new version is not “just upgrading the CH-53E. It is not a rebuild or remanufacture like most other new military helicopter programs.” He said that the airframe is changed from metallic to composite materials, that it is totally digital fly-by-wire, and that Sikorsky is using “brand new technologies” in the CH-53K. The aircraft was designed in Sikorsky’s design reality lab “that we have for reducing risks and overall costs to the program,” Zack said. This uses CAD/CAM protocol to create a full 3D rendering of the aircraft, allowing design teams to lay down systems such as fuel lines, hydraulics and harnesses, and to look for potential interferences, he continued. The design is then “imported into the digital operation sheets that we use to build the aircraft. It goes from paper to two-dimensional, then three-dimensional to a tablet that the mechanics and electricians—the artisans—can view right from their handheld tablets in a three-dimensional perspective.” Zack noted that the main rotor pylon has roughly a thousand interfaces, and was dropped down on top of the airframe “with a 99.99 percent precision. It had one hole that required a minor rework.” Wichita, Kan.-based Spirit AeroSystems built the major airframe (cockpit, cabin and airframe join), with the main rotor pylon from Aurora Flight Sciences, headquartered in Manassas, Va. Other major subcontractors include: ITT Integrated Structures (tail rotor pylon and sponsons); UK-based GKN Aerospace (aft transition); Onboard Systems (external cargo hook system); Hamilton (secondary power system, actuation and flight control computers); BAE (active inceptor systems and cabin armor, pilot/co-pilot seats); Triumph Aerospace (various dynamic components), Heroux-Devtek (landing gear systems); Sanmina-SCI Corporation (intercom system); and DRS Technologies (cabin floors/cargo handling system). The helicopter will have fully digital glass cockpit avionics from Rockwell Collins. According to Zack, the avionics “gets integrated into the systems integration lab (SIL) in Stratford, along with the flight control fly-by-wire control log development that is also occurring in Stratford, still with Rockwell Collins avionics management system loaded into the SIL. We have roughly three million lines of code, and 80 percent of that is functional in our SIL.” Three General Electric GE38-1 engines, each rated at 7,332 shp, will power the CH-53K. This compares to the three 4,750 shp GE-T64-GE-419 engines that power the CH-53E. This will provide a maximum gross weight of 74,000 lbs with internal payloads, or a MGW of 88,000 lbs with external payload, compared to the CH-53E MGWs of 69,750 lbs and 73,500 lbs, respectively. Zack noted that the CH-53K will have a payload of 27,000 lbs over 110 nautical miles under “high and hot” ambient conditions, nearly triple that of the CH-53E (see Rotor & Wing, June 2011, page M16).  “The GE engines now have more than 700 test hours, of which 300 are endurance tests,” Zack said. The first of the three engines for the GTV aircraft is scheduled for delivery at the end of July. The remaining two engines are scheduled for delivery later this year.

Sikorsky is now “actively working” to get under contract for the initial operational test and evaluation (IOT&E) phase, which is for the first four LRIP aircraft. The company has expanded its West Palm Beach facility by an additional 60,000 square feet to handle initial production of the CH-53K. The manufacturer is planning to produce 24 aircraft per month once full production begins, although the production site for those aircraft has yet to be determined. Total program at this time includes production of more than 200 aircraft. Initial operational capability (IOC) is projected in 2018.

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