Paul Lewis/WASHINGTON DC
The US Marine Corps must start work on the Sikorsky CH-53X modernisation programme in fiscal year 2004 if the service is to sustain its heavylift helicopter fleet beyond 2010 and dovetail expenditure with planned development and production funding for the Joint Strike Fighter (JSF), Bell Boeing MV-22B Osprey and Bell AH-1Z/UH-1Y upgrades.
USMC plans to upgrade 111 CH-53Es at a unit price of $22-26 million, about half the cost of a new helicopter. Engineering and manufacturing development (EMD) would be "below $1 billion" estimates Lt Col Curt Haberbosch, USMC assault support and executive helicopter requirements co-ordinator.
He adds that a funding window starts in 2004. The CH-53X would begin after AH-1Z/UH-1Y EMD is completed. Planning calls for 15 helicopter-a-year full rate production to start in fiscal year 2011 as USMC funding of the MV-22 and JSF begins to ramp down.
The other schedule driver is the projected CH-53E fatigue life. The critical structure is the tail rotor pylon/boom transition bulkhead, which is limited to 6,120h. At current 18.9h per month utilisation rates, the first helicopter will be grounded later this year.
Only five more CH-53Es are scheduled for withdrawal by 2010, after which there will be a rapid decline in the number of airworthy machines. To avoid a shortfall in heavylift capacity "we have to start in 2004 and even that's pretty tight as it leaves us only seven years", says Haberbosch.
Upgraded machines would receive new cabin centre sections and tail kits along with uprated powerplants, an elastomeric-bearing main rotor head and S-92-derived anhedral composite blades. Maximum take-off weight with an external load would increase by 2,270kg (5,000lb) to 35,640kg.
The 4,580kW (6,150shp) Rolls-Royce AE1107C turboshaft is the USMC's preferred new engine as it offers commonality with the MV-22. It also provides a better power margin, particularly in hot and high conditions.
Mission objectives are to extend the CH-53X's combat radius to 370km (200nm) matching the MV-22s and, with a new cargo-handling system, to triple its useful load to 12,700kg. The USMC hopes new dynamic components and a 1553-databus avionics suite will reduce the three-engined helicopter's $9,500/h flight cost and 42h per flight hour maintenance rate.
Source: Flight International
