A host of military aero-engines are scheduled to join the Indian armed forces in this decade

Unlike most air forces world over, which are standardizing their aircraft fleets with fewer types, the Indian Air Force (IAF) will enter the next decade with a multiplicity of platforms and associated engine technology. We take a look at the military Aero-engines that will join the Indian armed forces over the course of this decade and those already in service along with the technologies and benefits that they offer.

For the Rafale aircraft that will join the IAF in a few years time, India has picked M-88 engine. Safran Aircraft Engines designs, develops and produces the M-88 engines which will power the twin-engine fighter, available in both air force and naval versions. The Rafale entered French military service with M-88-2 engines that were delivered starting from 1996, and powered both air force and naval versions of Rafale. As of mid-2013, nearly 350 M-88s have been delivered by Snecma from its assembly lines in Villaroche. The M-88 features state-of-the-art technologies, including compressor ‘blisks’ (integrally-bladed disks), single-crystal high-pressure turbine blades, powder metallurgy disks, ceramic coatings, composite parts and nozzles made using Thermo-Structural composites. 

New aircraft rolling out from Dassault’s factories at the rate of 11 a year are now powered by the improved Snecma M-88-4E engine (formerly designated as the TCO Pack - Total Cost of Ownership). Development of the improved ‘4E’ version was sanctioned in 2008 with the aim of providing an extended service life with longer time between inspections for several parts of the engine. The M-88-4E was qualified in May 2012 and more than 30 units had been delivered to Dassault and the French air force as of mid-2013. Changes have been limited to the compressor and high-pressure turbine (HPT) and these new modules will be progressively integrated into the older M-88-2 engines as they come in for scheduled maintenance.

Compared to the older M53-P2 on the Mirage 2000, which has 12 modules, the M-88-4E has almost doubled the number at 21 and these are interchangeable without the need for balancing and re-calibration. According to Safran “some of these modules can even be changed without taking the engine out of the Rafale air frame, and a M-88 can be removed and replaced in under an hour.” Safran claims that “the M-88 is the only engine of its kind that can be returned to service after changing modules without requiring a new ground acceptance test – all that it needs is a simple leak test.”

The recently upgraded Mirage 2000 will remain operational with the IAF beyond 2040. The delta wing French fighter has had a very good safety record in IAF service and its Snecma M53-P2 engines have proved reliable and trouble free. India signed the contract to acquire the Mirage 2000 in October 1982 and the first aircraft arrived two years later. Work on the Snecma M53 engine which was based on the highly successful Atar engine family, began in 1967 and the M53-5 first flew in 1973. The Mirage 2000 flew for the first time in 1978 and an estimated 639 M53-P2 engines are currently still in service.

Snecma offers the improved M53-P3 for retrofit which offers ‘faster acceleration, improved specific fuel consumption (SFC) and simplified backup systems,’ and uses technology derived from the M-88 and CFM56. It features a 100 per cent full authority digital engine control (FADEC); that is now all-digital and fully redundant and increased life-span of hot parts for lower cost of ownership. An optional higher-thrust version is also being offered. It is not yet publicly known if the IAF has decided on any engine upgrades for its in-service M53-P2 engines. All M53-P2 engines manufactured since 2009 incorporated the following modifications of which the IAF chose to include the auto throttle. The modifications related to the automatic management of nozzle pump failure; the auto throttle (for automatic control of engine speed to maintain the speed chosen by pilot); and the integrated life potential computer, now included in the FADEC (full authority digital engine control). 

Depot level engine maintenance for the engine is undertaken in India after a maintenance Transfer of Technology (ToT) that was signed in 1993. In October 2014, Snecma (Safran) announced an agreement with Max Aerospace to create a joint venture (JV) called Max Aero Engines Private Limited (MAEPL), for maintenance services of the Snecma M53 engines powering the Mirage 2000H ‘Vajra’ fighters. The joint venture is offering complete engine support solutions, in particular shop-level maintenance and flight line services to the Mirage fleet.

Saturn AL-31FP Thrust Vectored Afterburning Turbofan

The largest fighter fleet in the IAF is the Su-30MKI series. The Su-30MKI is powered by powerful AL-31FP thrust vectored engines that provide the fighter with brute thrust and superb maneuverability. Hindustan Aeronautics Limited (HAL) established its Sukhoi Engine Division for manufacture and overhaul of AL-31FP engines. Overhaul work commenced in 2007 and since then more than 150 engine overhauls have been completed. Manufacture of the AL-31FP from raw material phase has also begun. The Koraput division is also seeing investments for manufacture of the AL-551 (for HJT-36 IJT) and its overhaul, modernization of engine division, augmentation of AL-31FP engine facilities for Su-30 MKI, RD-33 (MiG 29 engine) overhauling, RD-33MK (MiG 29k engine). In accordance with the provision for indigenous production under ToT agreement in the original contract, an Inter-Governmental Agreement (IGA) was concluded (October 2000) between the governments of Russian Federation and Republic of India for transfer of licence and technical documentation to India for production of 140 aircraft, 920 AL-31 FP engines and 140 sets of air-borne equipment to cater for the life-time exploitation of the aircraft. Koraput Division was to supply engines for the delivery of Su-30MKI aircraft and HAL was required to manufacture 410 engines to cater to the requirement of supply of 222 aircraft. The supplies were required to be made over a period of 13 years from 2004-05 to 2016-17 with production targets ranging from 4 to 74 engines per annum. 

Klimov RD-33 Turbofan

A number of Rolls-Royce (RR) military aero-engines are in service in India across the IAF for its Jaguar (Adour), Hawk (Adour, C-130), J ‘Super Hercules’ (AE 2100) and the Indian Navy (IN) for its Sea Harrier (Pegasus) and Hawk trainers. The Indian Navy have been partners since the formation of the Service, a great example being 300 Indian Naval Air Squadron (INAS), where RR has worked alongside the squadron for over 50 years. In the short term, RR says that its “priority is to support today’s fleets – in particular the Sea Harrier as it plays a vital role in India’s maritime security. In the medium, term we will continue to support the operation of the Sea King, a critical military asset, which has years of operation remaining.” Looking at the longer term, RR says “there are a number of Rolls-Royce powered aircraft that we believe could be of interest to the Indian Navy. The most obvious of these is the US-2I amphibious aircraft which shares largely common engines with the Indian Air Force’s C130J fleet.” Last year, RR received a USD 1 billion order for the supply of 588 AE 2100 engines, which ensures the engine will be fitted on all Super Hercules till 2025. 

IAF C-17 Globemaster III’s are powered by Pratt & Whitney’s F117-PW-100 engines each rated at 40,400 lbs. of thrust. The service has now taken delivery of all 10 Boeing C-17 Globemaster III airlifters. The engines along with the C-17’s advanced design are the key to the performance and versatility of the Globemaster. The C-17 can attain a cruise speed of over 0.74 Mach (906 km/h) and also fly very slowly. The thrust reverses on the engines allow the C-17 to taxi backwards even at maximum gross weight up a two per cent slope allowing for unmatched capability on small austere airfields. The reverses can also be deployed in flight to slow down the aircraft making it possible to carry out an approach to an airfield with a steep angle and a slow speed thus avoiding threats at a lower flying altitude and enabling an accurate touchdown to a runway with limited space. Engine maintenance and support is provided as part of the C-17 Globemaster III Sustainment Partnership, a Performance-Based Logistics partnership between the US Air Force (USAF), Boeing and Pratt & Whitney for which the IAF has signed up and so have all other customers of the C-17. Under this arrangement, C-17 operators receive an agreed-to level of system readiness, as opposed to a traditional contract for specific spare parts and support services. 

Helicopter Engines 

HAL Shakti Turboshaft Engine

Turbomeca currently has a wide range of helicopter engines in use in India today and these encompass the Artouste III B (HAL Cheetah and Chetak), TM333-2B2 (Dhruv MkII), TM333-2M2 (HAL Cheetal & Chetan), Ardiden 1H1/Shakti (HAL Dhruv Mk III & Mk IV). Turbomeca is also gearing up for the ‘Make in India’ strategy which will see an increasing amount of indigenous content being required for new helicopter and existing helicopter programs and is gearing up to meet this challenging requirement. It is also actively looking at increasing its customer support activity in India and has already been in discussions to partner with Indian companies for setting up of a maintenance and repair (MRO) facility in India.

Turbomeca TM333-2B2 Turboshaft Engine
When it comes to helicopter engine technology, the compressor, combustion chamber and turbine technologies are they key elements in the design. An official from a helicopter engine manufacturer told FORCE that “as we develop new technologies for our future product line, we have ambitious plans to reduce fuel consumption. This objective will involve integrating a very high pressure ratio compressor, fluctuating operating cycles and extremely high temperatures,” he said, adding, “Research activities are also devoted to developing the next generation of technologies; specifically high-temperature materials and coatings, light materials (magnesium, titanium aluminides), numerical simulation, acoustics and future engine control systems.”

Certified by EASA in 2009, Ardiden 1H1 is currently licence-produced in India by HAL under Shakti designation and has been selected to power Dhruv Mk-III and Mk-IV variants. Shakti entered service on the Dhruv MkIII helicopter in 2010 and it is estimated that around 75 Shakti-powered Dhruv are currently in service. The Shakti engine has also been selected to power LCH combat helicopter and has been designed for all helicopters in the 5 to 6.5 tonne class.

Amongst the key advantages of Shakti engine for Dhruv is the fact that the Ardiden 1 is a compact design built around a gas generator with two centrifugal compressor stages, coupled to a single-stage high-pressure turbine. It features easy maintenance and engine control to suit operator’s wishes for lower maintenance costs and optimum engine availability. It has simple modular design and dual channel Fadec that improves overall safety, reduces pilot work load. Its initial TBO is 3,000 hours, with no interim visit, including hot parts. The Shakti engine is fitted to Dhruv MkIII and MkIV helicopters and also the LCH and this will certainly be beneficial to the user in terms of cost of operation and maintenance.

Klimov TV-117 Turboshaft Engine
Continuing Turbomeca’s success in powering Indian indigenous helicopter programs was the selection of its Shakti 1U engine (a derivative of the Shakti 1H1 engine on Dhruv) for the Light Utility Helicopter (LUH). Turbomeca emerged as the successful bidder in the global tender process. The LUH engine’s FADEC would have control system software which will be specifically developed by Turbomeca for matching with the single engine application. The LUH will feature a dual channel FADEC along with an additional back up channel to provide extra safety margin for single engine operation (an important feature at high altitudes). Turbomeca is to develop the back-up control and perform other minor modifications as required by HAL. 

The IAF is also a major operator of Russian helicopter types (estimated at 300 examples) such as the Mi-8MT/Mi-17, Mi-24, Mi-35 and the Indian Navy operates Ka-28/31. These helicopters are powered by TV2-117 and TV3-117 engines developed by Klimov. The TV3-117 turboshaft engine family was developed in 1974 for Mi-24 and Mi-14 helicopters and went to be fitted on 95 per cent of all helicopters designed by Mil and Kamov Engineering Center. Over 25,000 TV3-117 engines have been manufactured since the start of production. (Text Courtesy Force India)

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