Upgraded Chinook:

 

 

          More Cargo at Higher Altitudes

 

 

             The U.S. Army’s CH-47 cargo helicopter has been a useful air mobility asset for U.S. Special Operations Forces and conventional Army units. But the fleet is aging, saddling the Army with growing maintenance and operation costs.

             For that reason, the Army initiated the CH-47F Improved Cargo Helicopter (ICH) upgrade program, which will add about 20 years to the life of older Chinooks. Although the program is expected to generate savings in operations and maintenance costs, it has been under close scrutiny at the Pentagon, as a result of significant cost overruns (National Defense, June 2002, pg. 14). But the upgrade work will continue, as planned, because other alternatives were deemed too costly.

             The office of the defense secretary recently estimated that the CH-47F unit cost will be about $22 million. The Chinook is now expected to remain in the Army inventory until at least 2033, 71 years after the CH-47 first entered service.

             Plans call for 300 of the 433 CH-47Ds in the Army inventory to become CH-47Fs. Within that total will be 36 MH-47G Special Operations Aircraft reclaimed from today’s MH-47D and -47E fleet, or from standard CH-47Ds. The ultimate number of Chinooks rebuilt for the Army could grow awaiting a Joint Combined Lift replacement around 2025.

             The first low-rate initial production CH-47F is scheduled for delivery in 2004.

             In May, Boeing delivered the first remanufactured CH-47F Chinook to the U.S. Army. The aircraft, serial number 8002, is one of two prototypes manufactured for the modernization program. Both helicopters began flight and system validation testing in 2001. Aircraft 8002 was scheduled to begin test flights at Fort Rucker, Ala., in late May. (* See note below)

             Boeing estimates it takes about a year to turn a D-model Chinook into a CH-47F. The company’s Philadelphia plant can upgrade at least four aircraft per month. Current remanufacture plans ramp up from seven improved Chinooks in fiscal 2003 to 27 in fiscal 2009, and conclude with 29 aircraft in 2016.

             The Army estimates that this upgrade will cut Chinook operating costs per flight hour from $2,526 for the CH-47D to $1,895 for the CH-47F. Additionally, the CH-47F will haul the Army’s heaviest loads at high-density altitudes and share information with other platforms.

             Boeing modernized U. S. Army CH-47A’s, B’s, and C’s to CH-47Ds from 1982 to 1994. When the aircraft reach the end of their 20-year operational life span, structures crack and avionics and other subsystems fail more frequently. Brittle wiring and corroding connectors also cause problems.

             In Afghanistan, Chinooks provided the power and range to haul worthwhile payloads at mountain elevations beyond the reach of Army Black Hawks. Army lift requirements have nevertheless outgrown the CH-47D. The D-Model Chinook was required to carry 15,000 pounds over 30 nautical miles, taking off at 4,000 feet on a 95-degree F day. The Army’s M198 howitzer with its crew and equipment weighs around 16,000 pounds, too heavy for today’s Chinook to lift under high-and-hot conditions.

             Plans for a CH-47 follow-on or CH-47(FO) with four-bladed rotors, new engines and fully integrated avionics emerged soon after Desert Storm, but proved too expensive for the Army budgets. Today’s CH-47F recapitalization is therefore not as ambitious as the CH-47D modernization. D-model remanufacture stripped every aircraft to bare structure for totally new wiring and plumbing, and replaced transmissions, rotor blades and engines.

             Much of the wear and tear on helicopters comes from vibration. By de-tuning the airframe with stiffer structures, the CH-47F remanufacture reduces both vibration and the weight of vibration suppression systems. Since most of the stiffening is up front, the CH-47F replaces the forward third of the fuselage with an entirely new cockpit section. The lower vibration levels demonstrated in EMD promise to reduce O&S costs and improve the reliability of avionics and controls, said Boeing officials.

             The rest of the aircraft structure is inspected for cracks and corrosion and repaired as necessary. While CH-47F remanufacture rewires the Chinook, it retains existing fluid lines. The aft rotor pylon of the CH-47F makes teardown and assembly easier, for rapid deployment.

             Original plans called for the CH-47F to use existing transmissions without changes. The Army has since agreed to overhaul the gearboxes as part of remanufacture. While the 7,500 shaft-horse power transmission of the Chinook is adequate to meet current Army lift requirements, the helicopter needs more high-and-hot engine power, program officials said.

             Separate from the recapitalization, the Army is upgrading the Honeywell (formerly Lycoming) 3,750 shaft-horsepower T55-L-712 turbo-shafts of the Chinook to 4,867 shaft-horsepower T55-GA-714A standards. The higher sea-level power margins of the improved engine will give the CH-47F enough high-and-hot power to carry a 16,000 pound howitzer with crew 100 nautical miles, three times farther than Army requirements. Despite the added power, gross weight of the CH-47F remains 50,000 pounds for now, equal to that of the CH-47D. Special Operations Chinooks and current export aircraft are about 54,000 pounds.

             Up front, the CH-47F introduces a glass cockpit that is less sophisticated than those found in some export Chinooks or the one planned for the new UH-60M Black Hawk. Boeing integrated the Chinook crew station around Rockwell Collins hardware and software on a MIL-STD 1553B databus.

             Each pilot has a control display unit (CDU) in the center console to host the entire system and give crew members access to communications and navigation functions. The CH-47F has dual GPS/INS navigators to drive the digital map and provide vertical speed information.

             An improved data modem gives the CH-47F access to orders and situation reports from joint air and ground units via a choice of radios. The communications package includes an ARC-164 UHF AM set with Have Quick II frequency hopping, dual ARC-201D VHF FM Sincgars radios, an ARC-186 VHF AM/FM radio and ARC-220 HF radio for over-the-horizon communications.

             The CH-47F uses the same aircraft survivability suite available in the CH-47Ds and international Chinooks. The ICH will have provision for a second M130 flare/chaff dispenser, and the databus can accommodate SIRFC and SIIRCM—the Suite of Integrated Radio Frequency Countermeasures and Suite of Integrated Infrared Countermeasures.

             Digital electronics in a reduced vibration environment promise higher avionics reliability and lower O&S costs. However, to control costs and moderate the integration challenge, the CH-47F retains the existing electromechanical instruments to display engine parameters. The new cockpit is not as integrated as the Honeywell Avionics Control Management System in Dutch CH-47Ds and International CH-47SDs. It has, for example, a stand-alone radar warning receiver display. Despite its new databus, it has no provision for a forward-looking infrared (FLIR) night vision sensor.

             The 160th Special Operations Aviation Regiment already has more capable avionics with the Lockheed Martin Integrated Avionics System in its MH-47Es, and the Rockwell Collins Adverse Weather Cockpit System on its MH-47Ds. The CH-47F remanufacturing line gives the Special Operations Command an opportunity to standardize the aircraft flown by the 160th SOAR.

             Notional plans call for six of the seven Lot 1 CH-47Fs to be upgraded to MH-47Gs, with enlarged fuel sponsons, air refueling probes, multi-mode radars, and new common avionics including color multi-function displays. The Rockwell Collins avionics architecture system is meant to standardize MH-47, MH-60, and A/MH-6 avionics software. Boeing will integrate the new avionics suite into the MH-47G cockpit.

             The CH-47F retains the analog flight control computer of the CH-47D, but a more advanced and supportable digital computer is in the works for Block 2F-model Chinooks.

             Note: The first Chinook delivered was 98-00011, Boeing build number M8001. Click-N-Go Here to read more. 98-00012 was Boeing build number M8002.]

 

 

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