CH-47F Block I/II Program: A Status Report

CH-47F Block I/II Program:  A Status Report

by Roger Breece and Mark Gulley

 U.S. Army Photo

The summer 2022 issue of Aircraft Survivability featured an article recognizing the 60th anniversary of the Army’s premier heavy-lift rotary-wing aircraft—the Chinook CH-47—and including some personal impressions about the aircraft from a retiring Army Chinook pilot [1].  As a bookend to last year’s article, this article provides readers with a brief update on the status of the CH-47 program, as well as the latest developments in the testing of the helicopter’s most recent model, the CH-47F, including developments related to the aircraft’s survivability, reliability, and safety.

CURRENT PROGRAM OF RECORD

The tandem-rotor, heavy-lift CH-47 continues to provide combat support and combat service support to deployed U.S. Army forces and more than 20 foreign military allies around the world.  The CH-47F Block II has been designed to buy back performance lost to ongoing weight increases, establish groundwork for future block upgrades, and accomplish midlife recapitalization.  The most notable Block II improvements include an improved drive train, an improved rotor system, a lithium-ion emergency power system, a lightweight fuel system, and numerous airframe commonality improvements.

The CH-47F Improved Cargo Helicopter (ICH) program began as a Service Life Extension Program (SLEP) for the Army’s fleet of CH-47D aircraft.  The program completed Initial Operational Test and Evaluation (IOTE) Phase II and First Unit Equipped (FUE) in 2007.  The F model received a Full Materiel Release (FMR) and Full Rate Production (FRP) decision.  In addition, the helicopteR—hereafter referred to as the CH-47F Block I aircraft, which comprises all the U.S. Army’s fleet of Chinooks today—has completed the Production and Deployment phase.

The Cargo Helicopter Modernization Project began as a response to the 2007 CH-47F System Evaluation Report [2].  Modernization projects focus on equipment changes driven by technology advances and obsolescence that could be applied to any H-47 Mission Design Series (MDS) aircraft.  These efforts have resulted in the Block II program.

Block II is an Acquisition Category (ACAT) 1C program, with the Army serving as the lead Service.  The program is an outgrowth of the Project Manager’s (PM’s) desire to efficiently accomplish engineering changes to the ACAT 1C ICH program.  The Cargo Helicopters Project Office is in the Program Executive Office for Aviation (PEO AVN) at Redstone Arsenal, AL.  The Milestone Decision Authority (MDA) is the Army Acquisition Executive.  The PM designed the CH-47 blocking strategy to insert incremental technology upgrades into the Chinook fleet to maintain the platform’s relevance and affordability over time while meeting Warfighter requirements.

CH-47F BLOCK II

The Block II upgrade buys back payload through power management and increasing maximum gross weight along with targeted subsystem weight reduction.  As such, the upgrade will support efforts of future Chinook increments to meet combat requirements while acknowledging that new Mission Equipment Packages (MEP) will continue to add weight to the system over time.  The upgrade also delivers improved aircraft performance, reduced maintenance workload, and enhanced crew safety.

The program addresses obsolescence and provides updates for the Common Avionics Architecture System (CAAS) and Digital Advanced Flight Control System (DAFCS) software, as well as incorporates a Product Improvement Program (PIP) included on approximately 171 CH-47F aircraft procured in the multi-year (MY) II production contract.  The PIP is an avionics obsolescence/ upgrade package initiated during the MYII production contract that will continue in Block II.  The Block II production configuration encompasses all upgrades to the Block I, along with the airframe and component upgrades shown in Figure 1.  The Improved Drive Train (IDT), only in the Block II aircraft, is especially key in contributing to increases in performance and reliability over the fielded CH-47F Block I.  Strengthened airframes and improvements to the fuel and electrical systems improve safety, survivability, and reliability for the aircraft.

Figure 1. Block II Upgrades.

At the time of this publication, Congress has appropriated funding to begin building Block II production aircraft even though the program is still in the Engineering, Manufacturing, and Development (EMD) Phase (Pre-Milestone C).  Six Block II production aircraft are currently under contract and are slated to begin production testing in 2024.

AIRCRAFT SURVIVABILITY EQUIPMENT FOR BLOCK I

The U.S. Army Block I fleet, which consists of 450+ aircraft, are in transition from a Federated Aircraft Survivability Equipment (ASE) suite to an Integrated ASE (IASE) suite, which incorporates all the ASE components into the CAAS displays and moves away from the older, stand-alone federated systems.  Still, most of the fleet is currently equipped with the older federated systems, as shown in Figure 2.

Figure 2.  CH-47F ASE.

The newer IASE suite consists of the following components:

• Common Missile Warning System (CMWS) (Gen 3) – AAR-57
• Laser Detection System – AVR-2B
• Radar Warning System – APR-39C(V)1
• Common Infrared Counter Measures (CIRCM).

The exact configuration of the Block II production ASE suite has yet to be determined, but the solution will be integrated into CAAS, as is the CH-47F IASE suite.

CH-47F KEY CAPABILITIES REQUIREMENTS

The key performance requirements for both CH-47F Block I and Block II originate from the Operational Requirements Document (ORD) (Change 4) [3].  These requirements are summarized in Table 1.  (Note that the operational requirements for Net Ready and Reliability and Maintainability are not listed.)

CAPSTONE DEVELOPMENTAL FLIGHT TESTING

Using three prototype EMD Block II aircraft, all the required governmental and contractor flight testing was completed in October 2022.  The month saw a significant developmental flight test take place at Fort Carson, CO, which tested the aircraft’s performance of its range and payload capabilities in operationally relevant environmental conditions—namely, 4,000 ft above ground level (AGL) and 95 °F density altitude (DA), otherwise noted as 4K/95 DA.

Figure 3.  Block II Carrying Two HMMWVs.

Noting that the self-deploy capability did not require 4K/95 DA conditions, the self-deployment key performance parameter (KPP) was performed in the region of the Redstone Test Center (RTC) at Redstone Arsenal in May 2022.  RTC also successfully demonstrated Block II’s cargo-carrying capacity using two High-Mobility Multipurpose Wheeled Vehicles (HMMWVs) with a total cargo weight of 16,000 lbs (12,100 lbs of which was the HMMWVs and 3,900 lbs of which was the internal cargo load) in environmental conditions approximating 2K/66F DA (see Figure 3).

KPP RESULTS

RTC experimental test pilots successfully demonstrated the self-deployment KPP with all-weather screens (AWS) installed and using fuel from three Extended-Range Fuel System (ERFS) II tanks.  A total distance of 1,106 nmi was flown, which is greater than the 1,056-nmi threshold value referenced in the ORD [3].  In addition, a fuel reserve of 36 min was recorded, which again exceeded the 30-min threshold value.

RTC also demonstrated the Block II’s cargo-carrying capability using a combination of external and internal loads equaling 16,000 lbs (12,100 lbs external and 3,900 lbs internal) and AWS.  The external cargo for the mission was unloaded after the first leg of the flight while the internal load remained onboard for the entire flight.  The EMD Block II flew a total of 103.8 nmi using 3,370 lbs of the 7,100 lbs of the fuel available in environmental conditions approximating 2K/66 DA.  Similar results were obtained using the Engine Air Particle Separator (EAPS), which forces the engines to exert more power to obtain the required range and payload parameters.

During the capstone developmental flight test event at Fort Carson (in operationally relevant conditions of 4K/95 DA), only the cargo-carrying missions were conducted.  This time, however, a Joint Light Tactical Vehicle (JLTV) was used in the external load mission using both EAPS and AWS, and the other external load featured an M777 cannon weighing approximately 10,000 lbs with an internal cargo load of approximately 6,000 lbs (see Figures 4 and 5).  An air assault mission was also conducted that simulated the internal load of 31 fully loaded soldiers, as would be the case in an actual air assault mission.

Figure 4.  Block II Carrying a JLTV.

Figure 5.  Block II Carrying an M777 Cannon.

For the JLTV mission with EAPS installed, the variant JLTV used was an M1279 A1, which weighed 16,230 lbs.  The JLTV was unloaded after flying a radius of 50.8 nmi, for a total of 106 nmi.  The aircraft landed with a fuel reserve of 32 min, exceeding the threshold value by 2 min.  The combat radius of 50.8 nmi with EAPS installed just exceeded the threshold value of 50 nmi listed in the ORD while the actual DA environmental conditions on the day of the mission were higher (7,130 ft DA) than the required atmospheric conditions of 4K/95F (7,122 ft DA).

The JLTV mission was repeated at Fort Carson with AWS installed, and the JLTV weight remained the same at 16,230 lbs.  The JLTV mission flew a radius of 51.9 nmi, after which the JLTV was unloaded.  The round-trip distance was 108.5 nmi, and the aircraft landed with a fuel reserve of 37 min, exceeding the threshold value by 7 min.  A demonstrated combat radius of 51.9 nmi was achieved in higher-than-required atmospheric conditions (4K/95F DA and 7,122-ft DA), equating to 7,140 ft DA.

Yet another cargo-carrying mission was undertaken at Fort Carson with an M777 cannon, an internal load that would equate to approximately 16,000 lbs, and EAPS installed.  The M777 weighed 10,060 lbs, and 5,340 lbs of ballast was loaded internally to provide a total cargo weight of 15,400 lbs, which was 600 lbs less than the stated KPP requirement.  Nevertheless, the aircraft flew a radius of 56.2 nmi for a total of 114.1 nmi and landed with a fuel reserve of 37 min.  The day-of-mission conditions were 6,950 ft DA.

The final EAPS mission flown successfully demonstrated the troop-carrying capability of 31 fully loaded soldiers.  As a Safety Release was not available at the time of these missions, the troop- carrying (i.e., air assault) mission was simulated using internal ballast that approximated the weight of 31 combat-equipped troops weighing 335 lbs each.  The Ballistic Protection System (added to the Cargo On/Off Loading System [COOLS]) was also installed.  Day-of-mission conditions were 7,460 ft DA, and the internal ballasting was 2,620 lbs to simulate mission equipment not installed on the test aircraft and an additional 10,660 lbs to represent 31 combat equipped soldiers.  The 10,660 lbs was unloaded after the first leg of the flight, simulating offloading of the soldiers, while the MEP weight remained onboard for the entire flight.  The aircraft flew a radius of 105 nmi (210 nmi total) and landed with a fuel reserve of 36 min, exceeding the threshold value by 6 min.  The threshold combat radius distance of 105 nmi exceeded the threshold value of 100 nmi by 5 nmi.

KPP MISSION SUMMARY

The Fort Carson missions were successfully conducted in operationally relevant environmental conditions, and in 2K/66F DA conditions, clearly demonstrating the Block II can perform the most important parameters of its missions pertaining to cargo-carrying and troop-carrying requirements.   This result contrasts with the current CH-47F Block I, which did not achieve these performance KPPs at its IOTE event in 2007.   In addition, the Block I aircraft has only gotten heavier since its IOTE due to adding even more MEP, which further highlights the importance of the Block II aircraft successfully demonstrating these key performance parameters.

ABOUT THE AUTHORS

Mr. Roger Breece is the Cargo Project Office Test Lead and Acting Chief of the Tech Management Division Lifecycle Support Branch for the Program Executive Office (PEO) – Aviation.  He has approximately 40 years of experience in aviation-related areas, including work on the F100 engine and its derivatives, the F-119, the RS-25 Space Shuttle main engine, the Comanche, the Armed Reconnaissance Helicopter, the Apache Block III, and the CH-47F Block I and II programs.  He also previously served as the Sensors Test Lead for the Aircraft Survivability Equipment PMO.  Mr. Breece holds a bachelor’s degree in mechanical engineering from Tennessee Technological University and a master’s degree in technology management from the University of Alabama in Huntsville.

Mr. Mark Gulley currently works as a Cargo Project Office Test Analyst for PEO – Aviation.  Having supported the Cargo Office for more than 22 years, he is also a retired Army aviation officer and previously served as an operations research systems analyst and evaluator with the Army Test and Evaluation Command.  Mr. Gulley holds a bachelor’s degree in mechanical engineering technology with the University of Dayton and a master’s degree in mathematics from the Colorado School of Mines.

References

[1]  Edwards, Eric. “The Chinook Turns 60:  A Pilot’s Perspective on the Old ‘Workhorse of the Sky.’”  Aircraft Survivability, summer 2022, https://jasp-online.org/asjournal/summer-2022/the-chinook-turns-60-a-pilots-perspective-on-the- old-workhorse-of-the-sky/.

[2]  U.S. Army Test and Evaluation Command.  “System Evaluation Report for the Helicopter, Cargo CH-47F.”  May 2007.

[3]  U.S. Training and Doctrine Command.  “Operational Requirements Document for the CH-47F Cargo Helicopter.”  Change 4, CARDS No. 05049, 12 June 2006.