MILITARY CH-47 and MH-47 CHINOOK
David C Isby provides an overview of the heavy-lift CH-47 Chinook still designed and built by Boeing in Pennsylvania
Boeing CH-47 Chinook – nicknamed Hook – heavy-lift helicopters have been carrying out critical missions since it first went into service in the early 1960s. A single Royal Air Force Chinook proved to be critical to the British land campaign in the 1982 Falklands war. More recently, US Army Chinooks and others operated by coalition air arms have moved and resupplied forces in Afghanistan, Iraq and Syria, across terrain that would otherwise have proven impenetrable to ground forces. In addition, US Special Operations Command MH-47Gs have provided a cutting edge for combat operations.
Block I deliveries
Boeing’s Ridley Park facility outside Philadelphia, Pennsylvania will continue to deliver the latest CH-47Fs – in the current Block I configuration – to meet current US and international orders through to FY2020. In 2018, SOCOM ordered eight additional new-build Block II configured MH-47Gs in two four-aircraft batches; this latest MH-47G configuration is currently in the engineering and manufacturing development phase dubbed EMD.
These latest orders will bring the total number of US Army Chinooks up to 542 (473 CH-47Fs and 69 MH-47Gs); the objective programme of record.
The orders placed for MH-47Gs in 2018 are for new-production aircraft which will replace older ones in service on a onefor- one basis; some two dozen MH-47Gs currently in service are airframes originally manufactured as CH-47s in the 1960s which were upgraded to MH-47G standard. The delivery of the eight new aircraft is designed to keep SOCOM’s overall fleet at a constant end-strength number.
The CH-47 Chinook is projected to remain in US Army service until 2060, enabled by multiple upgrades including those already planned such as the Block II programme, and those currently projected, such as fitting new engines.
CH-47F Block II upgrade
Future development of the CH-47 Chinook is focused on the Block II upgrade programme which is intended to bring many of the worldwide fleet up to a new common baseline configuration; this includes all US Army CH-47Fs and MH-47Gs, and those operated by international users.
Block II’s key objective is to restore payload capability, something that has eroded with time caused by adding systems and therefore weight to the original Chinook design that have not been matched by increased engine power. MH-47Gs which have sustained years of intensive combat operations, will be first in line to be upgraded.
The Joint Requirements Oversight Council (JROC) approved the Block II’s performance requirements in September 2016 followed by going through its critical design review and milestone B decision in April 2017, thereby starting the EMD phase of the programme.
Three Chinooks are currently being built by Boeing at Ridley Park to Block II EMD standard; the first is expected to fly in 2019, and the current timeline which is subject to revision for a production decision is expected in FY2021. Block II aircraft are expected to arrive at the first US Army unit in FY2023 and achieve initial operational capability in the FY2024-2025 timeframe. Upgrading Chinooks to Block II configuration will run until the 2040s.
So what does the Block II upgrade provide? Most imperatively an increase in the Chinook’s maximum take-off weight to 54,000lb (24,500kg) from the current 50,000lb (22,700kg). At the tactical level, the take-off weight increase will enable the new Joint Light Tactical Vehicle, which Block I configured CH-47Fs lack.
Advanced Composite Rotor Blades (ACRBs) are also included with over 60 hours of flight testing already complete on a CH-47 at Boeing’s Mesa, Arizona facility. Boeing has made a smart design decision since the ACRB does not require modification to the rotor head. Built with three different airfoil sections to each tapered blade, ending in swept-back tips, the ACRB is designed to provide 1,500lb (680kg) additional lift in hot and high conditions.
Improved vibration control allows the removal of 100lb (45kg) of material used for vibration isolation, making the Block II lighter and providing smoother flying. A redesigned composite-material fuel cell arrangement (providing a 500lb increase to the maximum fuel payload capacity) and an improved dualgenerator electrical system, based on that developed for the Canadian CH-147 Chinook, will be part of the Block II configuration.
Fitting of new flight controls, FADEC (full authority digital engine controls) and instrumentation will upgrade the Rockwell Collins Common Avionics Architecture System, currently used on Block I Chinooks.
Campbell, Kentucky plugged into the aerial refuelling basket of an MC-130 over the Adriatic Sea.
An anti-brownout degraded visual environment capability, being made ready for production to meet US Army requirements, will be fitted as standard, integrated with Boeing’s current Digital Automatic Flight Control System that aids landings during brownout conditions. In addition to these two systems, the BAE Systems Active Parallel Actuator Subsystem will provide tactile cues of potential performance limitations to reduce pilot workload.
Future upgrades
Currently, a new engine is not part of the Block II upgrade, but the configuration has been designed to incorporate one in the future.
The new Block II drive train incorporates a new-technology Ferrium gear steel alloy called C61, which enables transmission of 10% greater power than the current drive train in use. The Block II Chinook configuration is designed to accommodate a 7,500hp engine, compatible with any currently under development as part of the Future Affordable Turbine Engine (FATE) programme. These are being designed to provide an 80% increase in power-to-weight capability, a 35% increase in fuel consumption, 45% less production and operating costs and 20% service design life. Flight demonstrations of new FATE engine installations are scheduled to begin with the Chinook in 2019.
Building on anti-brownout research work, a joint US-Canadian programme is currently looking at developing autonomous operation capability for the Chinook. A capability to add autonomous flight could be integrated with the new digital flight control systems to be incorporated in the Block II. Flight demonstration of autonomous operation is scheduled for the FY2021-2022 timeline.
Moving BLOCK II to the right?
The US National Defense Strategy, released a year ago, made competition with great powers, with high-technology weapons, the main focus for the US armed services; this focus follows an emphasis on counterinsurgency operations dating back to 2001.
The US Army wants to respond to the new direction by investing more in its top modernization priorities, including the new, high technology Future Vertical Lift (FVL) rotorcraft of the programme, and less in updating existing legacy systems, such as the Chinook. Some 800-plus programmes are subject to being cut back or cancelled in order to reallocate some $25 billion of funding over five years.
While unconfirmed by the Department of Defense – budget numbers are pre-decisional until released and hence not discussed – there have been multiple press reports that topping the list of potential programmes to be delayed has been the Chinook Block II upgrade, facing a five-year delay to its IOC – to 2030 – as part of the FY2020 budget request that is due to be sent to Congress in early 2019.
Congress will have the final say over any change to the Block II programme, with Pennsylvania shaping up to be a battleground state as the 2020 presidential race gets under way, any decision will likely attract strong political interest.
For the US Army, delaying Block II production may appear a viable option at a time when it is trying to modernize its aviation capabilities. When all CH-47F and MH-47G Chinooks are upgraded to Block I standard, the Army will have a common force-wide baseline, allowing personnel to be trained to fly or maintain the same type regardless of where they are in the force structure. The Chinook has proved invaluable in combat operations worldwide since 2001.
But its perceived potential vulnerability – in the air and on the ground – to the longrange high-technology weapons expected to be operational in 2040 is worrying. New rotorcraft technologies may enable survivability through longer range and higher speeds. The reduced capabilities and risks inherent in operating a Chinook fleet all configured in Block I standard for five years longer than planned may appear, to the US Army, a logical trade-off.
Boeing has been planning on international sales and smaller US orders (such as the 2018 order for MH-47Gs) to provide a seamless transition between Chinooks in Block I and Block II configuration. A delay in the Block II schedule would mean Boeing would have to lay officurrent workers from the design team and the final assembly line alike. The company would also have to stop buying from subcontractors and suppliers, immediately, especially long lead-time items such as the new drive shaft components. A potential delay to the Block II programme could force Boeing to bear the expense of the cuts only to have to bear the expense of bringing workers, subcontractors or suppliers back to the Block II programme – or, more likely, finding replacements for them – five years later.
Boeing has said it is “quite concerned” that delays could lead to a substantial unit cost rise. This would, under the Nunn-McCurdy amendment requirements, require the US Army to explain to the Congress why the programme should not be cancelled. Disrupting Chinook continuity could raise the flyaway cost for international customers, possibly deterring future orders and complicating highly competitive export deals.
International Chinooks
America’s approval for the long-awaited British procurement of 16 additional Chinooks configured for special operations – based on the MH-47G – was announced on October 19, 2018. However, these new-production Chinooks are to be delivered in Block II configuration, starting around 2023, which – like the 2018 SOCOM orders – means they may be affected by any US Army delay to the Block II programme.
A current high profile competition may result in a sale of up to 40 Chinooks to Germany (where the CH-47F version has already been type-certified). Selection of a winning design had been scheduled to take place in 2018, but the announcement of a postponement was given in September. With Germany’s current heavy-lift CH-53G-series helicopters approaching the end of their service lives in 2025, the first replacement helicopters had previously been scheduled to be delivered in 2023, but the delay in the competition makes achieving this unlikely. A delay in Block II IOC has potential to affect the German competition because their predecessors are aging out of service; not the case with the US Army Chinook fleet.
German Chinooks would be operated in support of French helicopters, both in Europe and in out-of-area deployments. This has led to a new requirement in the German competition for aerial refuelling from Lockheed Martin C-130 series tankers operated by the Armée de l’Air. Currently, only the MH-47G has an aerial refuelling capability, which may be an advantage to its competitor, the aerial refuelling equipped Sikorsky CH-53K King Stallion, developed for the US Marine Corps. In Israel, the Chinook is considered the front runner in the competition with the CH-53K to provide a replacement for the Israel Air and Space Force CH-53s. The recent resignation of the Israeli defence minister has reportedly delayed a decision. Boeing has offered the Chinook as part of a force modernization package, which also includes second-hand Boeing 767 airliners (for conversion to tankers) and Bell-Boeing V-22 Osprey tiltrotors.
The Indian Air Force commenced Chinook pilot training in 2018, with 15 aircraft due to be delivered between 2019 and 2023. The Indian procurement has also been marked by increased industrial cooperation, with Boeing participating in the certification of products from Indian industry. Boeing also signed an agreement, earlier in 2018, with Saudi Arabia Military Industries to establish a maintenance, repair and overhaul capability that would be able to support the Kingdom’s Chinooks and other aircraft.
Indonesia announced, in September 2018, that it was interested in an initial Chinook procurement, believed to be for three to five aircraft. Boeing has been working to expand industrial cooperation with Indonesia on a range of programmes.
Earlier in 2018, the US government approved the sale of 17 CH-47Fs to Spain, allowing the replacement of current CH-47Ds on a one-for-one basis.
Chinook future
While the US Army may be interested in delaying Block II production, it may also look at buying more Chinooks because an increase in its force structure is being considered. In 2018, the US Army wanted to have Chinooks permanently based as part of its Europe-based 12th Combat Aviation Brigade, which has not had its own Chinooks assigned since the end of the Cold War. The 101st Air Assault Division also requires another company of Chinooks. In fact, no operator has yet replaced its Chinooks, and only one country stopped flying them – Argentina – because it could no longer afford them.
Under current planning, the US Army’s eventual Chinook replacement is defined in FVL Capability Set 4, which sets out what would be required for a new helicopter type that would enter service in the 2040s-2050s timeline, and eventually replace the Chinook in the 2060s. This puts the Chinook replacement behind the attack reconnaissance helicopter (FVL Capability Set 1) and the Sikorsky UH-60 Black Hawk replacement (FVL Capability Set 3). Chinook replacement is currently a longterm objective, although Sikorsky believes that its CH-53K would make a fine Chinook replacement.
Despite the uncertainty over the Block II upgrade, with both the US Army and international users, the Chinook will continue operate at the sharp end of the world’s conflicts for decades to come. AI
