The modernization of the RAF’s Puma fleet proved many detractors wrong. Limiting upgrades to necessities rather than “nice to haves” resulted in an impressive extension to the model’s out-of-service date.
By Andrew Drwiega
Every nation wants to be armed with the newest and the best aircraft and equipment. A highly capable modern force not only contributes toward a nation’s military being an effective deterrent, it also builds national pride among the populace of the country. But buying new does not always have to be the only option.
Even in the context of the incredible cost of today’s high-tech military systems, sometimes, a new model is the most appropriate choice. And sometimes new is justified when an aviation platform passes the point where proposed upgrades cannot produce an outcome that justifies the investment.
The latter was the case for the U.S. Army’s Bell Helicopter OH-58D Kiowa Warrior. After years of the Army trying to replace it, the combined impact of sequestration and the cost of the proposed life-extension program finally resulted in it no longer being feasible to justify the cost of additional upgrades.
By contrast, Boeing’s CH-47 Chinook, even though it first flew in 1961, 5 years before the OH-58D, has been successfully adapted and upgraded over time. The model’s size and role add to the difficulty of designing a replacement that would not be prohibitively expensive. Thus, it has continued to serve as the U.S. Army’s front-line, heavy-lift rotorcraft.
At the same time, the CH-53, a rival helicopter made by Sikorsky (now owned by Lockheed Martin), is being further refined in its newest version, the CH-53K King Stallion. Development work was approved by the U.S. Congress at the end of 2005 for a replacement for the CH-53E used by the U.S. Marine Corps. At the end of 2005, Congress approved Research Development Test and Evaluation (RDT&E) efforts during the Fiscal Year 2007. Yet the project has been drawn out, due to engineering difficulties and government concerns regarding rising costs, to the extent that production deliveries are not expected to begin until 2020.
There are occasions, however, where extending an older platform initially is met with objections and dissent, but actually is managed in a way that ultimately justifies the cost of providing an interim solution. Such is the case with the upgraded Puma Mk2 fleet flown by the U.K.’s Royal Air Force (RAF).
Puma Projected from 1970s to 2025
The U.K.’s Ministry of Defence (MoD) started taking delivery of its first Aérospatiale SA 330 Pumas in 1971, with the first squadron (No. 33) becoming operational at RAF Odiham in June of that year. Over its life, this reliable workhorse has been involved in many operational theaters, often in support of the U.K.’s Special Operations Forces (SOF), due to its small rotor diameter, which allows entry into tight landing zones, including urban areas. Used extensively during “The Troubles” in Northern Ireland, it also served in Belize, Bosnia, Iraq, and more recently and sparingly in Afghanistan, where it was used to support the SOF.
The original out-of-service date for the Puma was 2005, and that was initially extended to 2008. However, in December 2009, U.K. Secretary of State for Defence Bob Ainsworth announced the Future Rotary Wing Strategy, which confirmed a £300 million (about $374 million U.S.) decision to extend the Puma’s out-of-service date to 2022 through a Life Extension Program (LEP). This strategy included driving the U.K’s. armed forces toward operating a maximum of four helicopter types: the Boeing CH-47 Chinook and AH-64 Apache, the Leonardo (then Westland) Lynx, and the AugustaWestland (now Leonardo) AW101 Merlin.
There was significant objection to the Puma LEP, even from within the government’s own ranks. In 2010, the Defence Select Committee declared, “We remain unconvinced of the financial or operational merits of the Puma Life Extension Programme. We believe that the MoD has underestimated the technical and operational challenges of the Puma programme, and that there is insufficient evidence to support the MoD’s assurances of the crashworthiness and the likely delivery dates of the updated aircraft.”
The Ministry of Defence countered the select committees arguments, stating that the Puma was chosen for the LEP specifically to leverage investments that had already been made to the model. Adding to the fact that the Puma fleet “has only flown half of the Service Life for which the original designer, Eurocopter, has cleared the airframe,” the government stated, “the modifications under the LEP, in particular the new engines, will provide 35 percent more engine power delivering far greater performance in the high altitudes and hot summer temperatures as currently experienced in Afghanistan; they will also provide a 25 percent improvement in fuel efficiency, providing greater range. The new cockpit will bring the aircraft up to date with digital displays and modern navigation and communication equipment.”
Replying to the issue of “poor survivability,” the MoD stated that the improved engine power and the addition of digital avionics “will address the principal safety hazards associated with the platform…” leading to “… a significant step change in capability, specifically enabling the aircraft to perform very well in Afghanistan’s exacting ‘hot and high’ environment.”
The initial plan was for twenty-eight Puma Mk1s to be converted to Puma Mk2s; this was cut back to twenty-two but rose again to the final figure of twenty-four. The Puma LEP was to be contracted to the Airbus Group (then Eurocopter), which would conduct the redesign and development of the first four aircraft at its Marignane facility in the south of France.
Once the testing and design was approved, the remaining conversions would be carried out at the company’s Romanian facility. While Romania was initially viewed as a strange location for this work to take place, in 2002, a partnership agreement had been signed between the Airbus Group and IAR, a Romanian aircraft builder with extensive experience in heavy maintenance.
According to Ian Morris, Vice President of Defence at Airbus Helicopters U.K., the Romanian partner was selected for the majority of the conversations as it had “a long and illustrious career, especially with the SA330, in building this specific type. They had done conversions like this for other customers so were suitable for the task.”
Morris also explains that the fundamental requirement stipulated by the MoD for the whole project was that it had to be “a low-cost, life-extension programme [which would] take out obsolescence. The direction was that there should be no capability increases other than those that came about by the avionics and engine upgrades.”
Not an Upgrade at Any Cost
The obvious change was taking out the analog cockpit and installing digital avionics that had already been qualified by Airbus on other models within the class, which would significantly reduce the qualification time. “This was using known components that all hung together with each other but not necessarily on the same platform. You can do this on the basis that they have worked together on other platforms, although they still had to be qualified on the Puma Mk2,” points out Morris.
“An audit was taken of what would become obsolete or run into obsolescence during that period, and this drove what needed to be changed,” he continues. “Under the Puma Mk1 Through Life Support (TLS) contract, the team was already aware of what was becoming more difficult to maintain, and we were also providing guidance for what would not be maintainable in the future and what the options for change were.”
The other big issue was the engines, twin Turbomeca Turmo IVC turboshafts (1,560 shaft horsepower each). At the time, these were considered too underpowered to continue though the LEP. The new Makila 1A1 that were selected to replace them deliver a take-off power of 1,820 shaft horsepower. They also have anticipators, which provide more instantaneous power, as well as an additional safety feature. The digital glass cockpit also means that pilots now used a heads-up digital display that increased their situational awareness.
The original, simple Flight Management System (FMS) has been replaced with the Esterline CMA-9000 system. The new FMS uses proprietary software that enables it to interface with the new Puma Mk2 avionics.
“But the constant behind every upgrade suggestion was that the more new items that you add, the greater the cost and the time which would be required. The decision was take to upgrade the aircraft out to a certain point, and I think that was vindicated,” states Morris. “The Mark 2 could also have been fitted with a full authority digital engine control (FADEC), but that was not required to allow it to do its job. It has a part mechanical, part electrical engine control system, which is very effective,” he adds.
When the first four aircraft proceeded to Marignane, Morris notes, “It was all about speeding up delivery. Key individuals from within the organization transferred to work inside the hanger to be close to the project.”
There were differences in build standard between aircraft, as some had been made by Westland (now Leonardo) in the United Kingdom, and others were South African Air Force helicopters that had previously been reconfigured for the RAF in Romania. According to Morris, the selection criteria used to identify which Puma helicopters within the existing fleet would be upgraded included those with longer airframe life but also those that had been recently modified for MoD equipment, such as defensive aide suites.
Designers worked alongside engineers during this initial period to develop the kit package and the manual that would be needed by the Romanians during their conversion of the remaining twenty aircraft. Before leaving the United Kingdom, the Puma Mk1s were stripped of any MoD-sensitive equipment, as well as the old engines, as the new, more powerful Turbomeca Makila 1A1 turboshaft engines were due to take their place. Each individual Puma then was transported via the MoD’s own movement system to either Marignane or Romania by road.
Once the conversion was completed and initial flight tests had been successfully concluded, RAF aircrews flew the rotorcraft back. “When they returned to the U.K., Airbus Oxford refitted all the MoD-sensitive equipment,” says Morris.
The Puma Mk1s were stripped down. This involved taking out all the old cable looms, which were replaced and repositioned to provide redundancy in case of battle damage.
The change from analog to digital avionics and the new engines still allowed Airbus to requalify the helicopter for airworthiness under the U.S. Federal Aviation Administration’s FAR (Federal Aviation Regulations) 29 as well as to meet the U.K. Ministry of Defence’s DEF STAN (Defence Standards) 00-970. The first aircraft completed at Marignane was used for flight testing and confirmation of the qualification requirements.
A further improvement was the upgrade of the self-sealing fuel tanks from being able to withstand punctures by 7.62mm rounds to damage by the larger caliber 12.7mm ammunition. Extended range fuel tanks also were included as part of the upgrade, as was improved ballistic protection, a more modern communications suite, and better defensive aides. “Weapons mounts were changed and made more flexible. There was also a requirement to change the position of the winch, so that it was positioned externally rather than internally,” describes Morris.
The first Puma Mk2s were delivered to the RAF during 2012, with the final aircraft arriving in 2015. The RAF was able to declare IOC by February 2015, ahead of schedule and within budget. Full Operational Capacity (FOC) was declared almost a year later in January 2016. Following the completion of the Puma LEP, a further defense review concluded that the out-of-service date for the upgraded Puma Mk2 could be extended to 2025.
Finally, a 3-year interim support arrangement (ISA) was established, including logistical support and crew/maintainer training, at a facility at Airbus Oxford (located close to the home of the Puma fleet at RAF Benson). Airbus is now in discussions with the MoD over the next stage of logistical support to determine the scope of a full support arrangement (FSA), which should take the aircraft through to its out-of-service date.
Reports from aircrew who have flown the Puma Mk2 have been very positive regarding the aircraft’s improved operating envelope. The upgraded Pumas, now able to tackle the rigors of flying in Afghanistan, were deployed in March 2015 to Kabul to support Operation TORAL, the North Atlantic Treaty Organization’s (NATO’s) training and support mission in that region. Not long thereafter, RAF flight crews declared that they had exceeded 10,000 flight hours in the upgraded Pumas as part of the U.K.’s contribution, named Resolute Support.
As Morris points out, “The aircraft has been such a success in Afghanistan that, of all the various international nations that contribute to rotorcraft around Kabul, while the Puma force equates to [just] 12 percent of the fleet last year, [it] delivered 24 percent of [the total] lift capability.”
Speaking earlier in 2016, Group Captain Simon Paterson, the U.K.’s Puma Force Commander commented, “While it may still look like the original Puma Mk1 to the untrained eye, the leap in capability has been profound and has made a real difference to the operational output of the Puma Force.”
Image #1 - An RAF Puma Mk2 taking off from its home base, Royal Air Force Benson airbase in the United Kingdom. (Image courtesy of the RAF)
Image #2 - Although representing only 12 percent of the allied helicopter force in Kabul, the U.K.’s Puma Mk2’s provided 24 percent of the allies’ total lift capability in the region in 2015. (Image courtesy of the RAF)
Image #3 - One of the four initial Puma Mk1s undergoing engine replacement work at Airbus Helicopters’s Marignane facility in the south of France (Courtesy of Airbus Helicopters)
Image #4 - A Royal Air Force (RAF) Puma Mk2 is being loaded onto a C-17 Globemaster transport aircraft at Brize Norton RAF airbase in the United Kingdom, for the 3,608 mile journey to Kabul, following declaration of Initial Operating Capability (IOC) in 2015. (Image Courtesy of the RAF)
Image #5 - Taken during the European Defence Agency’s Hot Blade Exercise in Portugal 2014, this photo shows the Puma MK2’s digital glass cockpit. (Photo by Andrew Drwiega)