Accessory drive train (ADT) is an aircraft engine equipment used in the transmission system. It is not a part of engine’s core, yet it drives important accessories, such as fuel pump, hydraulic pump, oil pump, and generator, of an aircraft. ADT performs primarily two functions: First, during startup, it transmits torque from starter to engine core for it to come in motion; and second, to transfer the mechanical energy of the engine turbine to drive the accessories of the aircraft. ADT comprises four main components: accessory gearbox (AGB), internal gearbox (IGB), external gearbox (EGB) and radial shaft. AGB acts as the heart of an ADT.
Aeroengine ADT has undergone a remarkable transition over a period of time, especially with regards to the weight reduction and increase in the power transmission capacity. For instance; Safran Transmission Systems recently developed an ADT for LEAP engines, certified for A320neo, B737 Max, and C919 aircraft programs, which reduces the ADT’s weight by 20% and improves the power transmission capacity by 30% as compared to the ADT used in the CFM56 engine. It is expected that weight reduction and improvement in the power transmission capacity would remain an indispensable focus area of the market.
All the major engine manufacturers are working closely with the tier players in order to develop efficient ADTs addressing their current as well as emergent requirements. Another remarkable transition is taking place with regard to a material shift as the industry is chiefly moving towards magnesium with the purpose of making parts lighter, yet offering higher specific strength and better heat tolerance.
ADT differs greatly from aircraft to aircraft based on the engine size, engine type, and complexity of the aircraft in which they are installed. For instance; ADTs used for turbofan engines will be considerably different than those ADTs used for turbojet engines, turboshaft engines, and turboprop engines. Hence, the selection of ADT as per the engine type is of paramount importance for safe operations and increased efficiency of an aircraft.
As per Stratview Research, the global aeroengine ADT market is projected to grow at a healthy rate over the next five years to reach US$ 802.1 million in 2023. Organic growth of aircraft industry is the primary driver of the sustainable demand for aeroengine ADT in an aircraft. Boeing anticipated that there would be total deliveries of 41,030 commercial aircraft worth US$ 6.1 trillion in the global marketplace during 2017-2036. Asia-Pacific and North America would be the biggest demand generators with a combined share of 63.3% of the total commercial aircraft deliveries during 2017-2036. An expected healthy CAGR of 4.7% in air passenger traffic during 2017-2036 will chiefly drive the demand for commercial aircraft. This factor will create a sustainable demand for aeroengine ADTs globally in the foreseeable future.
In addition to that, Boeing and Airbus had a combined total order backlog of 13,129 commercial aircraft by the end of 2017. These huge pile of order backlogs of commercial aircraft will allow both the airframers to roll out their aircraft continuously for the next nine years at current build rates. However, they have strategically been raising the production rates of their key commercial aircraft programs in order to deliver aircraft to their widespread clients at a shorter period of time. Also, they have been introducing fuel-efficient variants of their best-selling aircraft programs with the purpose to address the biggest requirement of the airline industry, i.e. the need for fuel-efficient aircraft.
The global aeroengine ADT market is segmented based on the aircraft type as Commercial Aircraft, Regional Aircraft, General Aviation, Military Aircraft, and Helicopter. Commercial aircraft is likely to remain the growth engine of the market during the forecast period. Increasing production rates of key aircraft programs, such as B737, B787, A320, and A350XWB; introduction of variants of the best-selling aircraft programs (A320neo, B737 Max, B777x, and A330neo); an advancement in the ADT technology; and market entry of new aircraft (C919 and MC-21) are primarily driving the demand for ADTs in the commercial aircraft segment.
Based on the engine type, the aeroengine ADT market is segmented into Turbofan Engine, Turboprop Engine, Turbojet Engine, and Turboshaft Engine. Turbofan engine is likely to remain the most dominant segment of the global aeroengine ADT market over the next five years. The segment is also likely to grow at the highest rate during the same period. Turbofan engines are primarily used in commercial aircraft. All the major commercial aircraft programs, such as B737, A320, B787, and A350XWB, rely on turbofan engines.
Based on the material type, aluminum is currently the most widely preferred material to make aeroengine ADT components and is likely to remain the most dominant material in the market during the forecast period as well. It is considered an ideal material for producing housings of ADTs. Whereas, magnesium, another considerable segment, is likely to grow highest in the market during the same period, driven by its advantages over aluminum including good tensile strength, creep resistance at elevated temperature, and excellent vibration damping characteristics. This makes the material an ideal choice for both main and accessory gearbox casings. Steel is the major material used to produce gears for gearboxes. They also offer sizeable growth opportunities in the coming years.
Based on regions, North America is projected to remain the largest market during the forecast period, driven by the presence of both large- to small-sized aircraft OEMs, aeroengine manufacturers, ADT manufacturers, component manufacturers, distributors, airline companies, and raw material manufacturers. The USA is likely to remain the growth engine of the region’s market during the forecast period, driven by all the assembly plants of Boeing in the country as well as large commercial aircraft fleet. The region is also the largest regional aircraft and business jet market worldwide.
Asia-Pacific is likely to witness the highest growth during the same period, driven by a host of factors including increasing demand for commercial aircraft to support the rising passenger traffic, opening of assembly plants of Boeing and Airbus in China, upcoming indigenous commercial and regional aircraft (COMAC C919 and Mitsubishi MRJ), and rising aircraft fleet size.
The supply chain of this market comprises raw material suppliers, aeroengine ADT manufacturers, aircraft engine manufacturers, and aircraft OEMs. Key aeroengine ADT manufacturers are Avio Aero, BMT Aerospace, Liebherr Group, Northstar Aerospace, Safran Transmission Systems, The Timken Company, Triumph Group Inc. and UTC Aerospace Systems. Key aircraft OEMs are Boeing, Airbus, Bombardier, ATR, Embraer, COMAC, Irkut, Sukhoi, Cessna, and Gulfstream.