King Stallion Trots Toward Flight Test Program   

By By Andrew Drwiega, International Bureau Chief | October 2, 2014

Sikorsky's CH-53K at the rollout ceremony on May 4, 2014 at the company's facility in West Palm Beach, Fla. Photo by Andrew Parker 

Combat unit training scenarios must include a continuum of threat levels designed to train students to avoid, degrade, defeat or destroy threat systems in order to survive. Man-portable air defense systems (MANPADs), present one of the most lethal threats to helicopters since Vietnam. Training to deal with them is nearly impossible. The CH-53K, or King Stallion as it has been christened by employees at Sikorsky, will be the second largest of the world’s rotorcraft heavyweights, giving way only to the incredible size of the Russian Mi-26.

The King Stallion is destined to replace the United States Marine Corps’ (USMC) existing CH-53E heavy-lift helicopters and is scheduled to begin its placement with Marine aviation units from 2019. The rotorcraft will not only replace its predecessor, but will out-lift it by a factor of three to one. Each of its three General Electric GE38-1B engines will provide over 3,000 shaft horse power (SHP) more than the old General Electric T64-GE-416/416As. It has been designed to lift 27,000 lbs over a range of around 110 nautical miles (nm) in keeping with the USMC’s stipulated require-ment for littoral lift.


On April 17, the first ground test vehicle (GTV) with all seven main rotor and four tail rotor blades attached fired into operation at Sikorsky’s Florida Assembly and Flight Operations plant in West Palm Beach, Fla.

Colonel Robert Pridgen, the USMC’s program manager for heavy-lift helicopters reported that the event was another indication that the program was on track following the bare head testing (no rotors attached to the rotor hub) under full power that progressed through January.

“This successful light off of powered ground tests reinforces our confidence in this team and our aircraft to meet the U.S. Marine Corps’ future heavy-lift mission needs,” said Pridgen.

He added that the “discipline and hard work” that had been demonstrated to get the project thus far, needed to be continued “with respect to dynamic and system-level performance” of the CH-53K. While it was expected that the first flight would occur late in 2014, this has already been pushed back to 2015.

According to the U.S. Government Accountability Office’s (GAO) report to the Congressional Committees on Defense Acquisition in March 2014, the delivery of the test vehicles had been delayed. The report cited that “the CH-53K design appears stable, but it has not been demonstrated using a system-level prototype to show that it will perform as expected. The program has reported that they are relying on delivery of test vehicles to demonstrate their design.”

The report attributes the delays, as noted by the Defense Contract Management Agency (DCMA), to factors including “late qualification testing, qualification test failures, re-testing, and the qualification of software. The delays have affected aircraft test schedules as well.”

At that time, as a result of the delays, the production decision had been moved to February 2016. Delays have resulted in cost increases, which is why customers beyond the USMC are being actively sought.

However, once GTV work is finally completed, it will lead into a three-year flight test program which will be based around four flight test aircraft. These will begin the final stages of production later this year with delivery expected in 2016-17. The flight test program will gradually increase in complexity over time until it can eventually demonstrate its full operating potential of the helicopter. Each of the four flight test aircraft, known as engineering development models (EDMs), is predicted to accumulate around 500 test hours, during which they will address different elements of the testing program.

By replacing the CH-53Es with a helicopter offering triple the payload over the same mission radius will speed up mission profiles by allowing faster insertion and build up of forces. The CH-53K has the same footprint as its predecessor.

The program of record for the USMC remains at 200 King Stallions (including test aircraft) which will be divided between eight front-line squadrons and a training squadron.

CH-53K on display in West Palm Beach, Fla. Photo by Andrew Parker

Replacing the CH-53E

The CH-53E was itself a replacement for the CH-53D in the USMC. In 1967, the USMC wanted a heavy helicopter with more lift, around 1.8 tons more, in fact. To reach this level of performance, Sikorsky needed to add a third engine, which it did during prototyping. The company also increased the size of the rotor system and added a seventh blade. In order to handle the power, a stronger transmission was required and Sikorsky extended the fuselage by six feet, two inches (1.88 m). The rotor blades were also changed to a titanium-fiberglass composite, and the tail rotor was made larger and tilted to add extra lift while in the hover.

The first CH-53E flew in 1974, and the first production model flew in December 1980. It could now lift 30,000 lbs internally or 32,000 lbs externally. It had a maximum speed of 170 knots without the external load. The USMC and Navy ordered a total of 177 rotorcraft.

In 2006, the U.S. Naval Air Systems Command (NAVAIR) awarded Sikorsky a $3.6 billion contract to design and develop the successor to the CH-53E. The contract stipulated the design and build of one GVT and four EDMs. There would also be two GTVs for static testing and fatigue testing.

In addition to the extra weight that the helicopter should lift, the USMC also stipulated a 23 percent reduction in maintenance time, a 20 percent reduction in fuel consumption, and better survivability.

The early years of the program were dogged by delay, which has caused it to run almost four years behind the date originally envisaged when development started in late 2005, according to the GAO report published in April 2011. The total funding required to deliver 194 operational aircraft to the USMC is more than $20.6 billion, according to the GAO report released in March 2014.

Technically speaking

 Computer-generated depiction of CH-53Ks. Image courtesy Sikorsky

The CH-53K is an all-digitally designed helicopter, according to Sikorsky, to the extent that it has even been assembled in a 3D virtual reality lab within Stratford. The redesigned composite airframe is lighter, reduces vibration and maintenance while increasing airframe survivability.

It features digital fly-by-wire avionics, netcentric tactical data links, split torque transmission within the rotor drive system to help distribute power evenly, an elastomeric main rotor head and new generation composite main rotors. The main rotors also feature an advanced airfoil section and an anhedral tip which contributes to life. The Health and Usage Monitoring System will further contribute to reducing maintenance issues, particularly valuable while on deployment.

Other features include a new defensive protection system, three onboard machine guns, and a triple-hook cargo handling system.

The size of the challenge that faced Sikorsky can perhaps be understood more when the fact that the 12,600-lb transmission and gear assembly weights more than a standard UH-60 Black Hawk.

A small but valuable addition was the planned inclusion of a composite flex beam in the tail that attaches the spar, upper skin and lower skin in each rotor blade to the rear horizontal shaft. This was the result of a Small Business Innovation Research (SBIR) contract from NAVAIR in 2011 to custom manufacturing solutions developer Accudyne Systems.

The objective was to reduce the production cycle time of each composite flexbeam, which was a very man-hour intensive process, from 40 to 10 hours through automating the process. This would not only accelerate production but also cut cutting labor costs.

On August 4, General Electric was awarded a $68 million modification to a previous contract for 16 GE38-1B engines, closure kits, tooling, and associated systems engineering and program management in support of the CH-53K helicopter program. Work will be performed in Lynn, Mass.

International Market

Rotor blades of the CH-53K. Photo by Andrew Parker.

Sikorsky may potentially be able to add 100 additional CH-53Ks to its planned production target, claiming them to be for international customers without specifically identifying who those customers are.

Speaking at the Berlin Airshow earlier in the year, the U.S. Navy’s international program manager for heavy-lift helicopters said that there was a possibility for up to 100 extra orders.

The most obvious of these would be the German Air Force, which owns Germany’s fleet of 66 CH-53s (it did have 84) that were transferred from German Army Aviation (Heersflieger) in January 2013. The modernized CH-53GAs are being delivered under license by Airbus Helicopters, which is also responsible for maintaining the fleet through a contract with the German government that was initiated when Germany bought its first batch of CH-53s from Sikorsky.

The Luftwaffe fleet is operated from two locations: Laupheim and Schonewalde/Holzdorf. Eventually the fleet will comprise a range of CH-53GS/GE/GA aircraft that have been gradually upgraded since the beginning of the century. There will be 20 CH-53GS (Special) aircraft; 6 CH-53GE (Enhanced) and the remaining 40 CH-53GAs (Advanced). The latest upgraded aircraft are scheduled to be in service until around 2030.

The European Defence Agency’s (EDA) Ministerial Steering Board approved a Category B program on May 18, 2009 to develop a Future Transport Helicopter (FTH) based around commonly identified Franco-German requirements of a Heavy Transport Helicopter (HTH).

The helicopter would weigh between 32 and 35 tons with an expected delivery date of 2020. It outlined a European requirement for such a helicopter to be capable of lifting up to 33,000 lbs. However, after the active participation of both Airbus Helicopters and Boeing, and in fact the selection of a preferred type of helicopter that was akin to a larger version of Boeing’s CH-47 Chinook.

May 2014 rollout of the CH-53K rollout. Photo by Andrew Parker

By 2011 the EDA’s FTH team had received responses to a Request for Information (RFI) from industry and were assessing the results to be incorporated into a business case document for Member States to review in 2012.

While Germany had led this program, other participants had been sought but with no success. The slashing of defense budgets in Europe meant that the two leading nations could not afford to enter into a new ‘heavy-lift’ development program by themselves. Consequently it is no longer on the EDA’s public ‘to do’ list regarding the expansion of European helicopter capability, preferring instead to focus on multinational training.

With an obvious German requirement to begin replacing its CH-53 fleet around or before 2030, Sikorsky may consider that its CH-53K is now the only game in town.

Other potential Foreign Military Sales (FMS) customers could include the Israeli Air Force who are a major operator with around 37 CH-53 Sea Stallions and the Japanese Maritime Self Defense Force which have six CH-53Es. Sikorsky may have identified potential new operators, perhaps in the cash rich nations of the Middle East and Asia (where nations are building their maritime capability in view of China’s geographical expansion plans.


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