Aircraft is a very complex machine, with multitudinous components, each performing a critical function to ensure that the aircraft functions flawlessly. Like the human body which has a network of blood vessels performing many functions like temperature & pressure regulation, aircraft also has an intricate network of cables and ducts which perform many vital functions.
Ducting is a vital component of the fluid conveyance system and air management system. Ducting facilitates the distribution of critical fluids & air throughout the aircraft, thus ensuring proper temperature regulation, ventilation, fluid, water and fuel flow, humidity or containment control, anti-icing and noise attenuation, etc. These are critical functions and failure of any can lead to fatal consequences.
The ductings are generally made of two types of materials, either metal or composites. Below are the details of the materials used.
|
Metals |
Inconel, Stainless steel, alloys of Titanium & Aluminium and other exotic alloys. |
|
Composites |
Reinforcement: Glass fiber, Carbon fiber, Aramid fiber Matrices: BMI and epoxy resins are the major matrices. Types: Thermoset or Thermoplastic composites |
|
Others |
Elastomer such as Silicon, Hastelloy, foams and Neoprene |
The choice of the material is based upon the property that is desired, which alters with the nature of the application. Following are the specific properties of the materials and their main applications.
|
Material |
Properties |
Applications |
|
Inconel 625 and 718 |
Highest strength, corrosion resistance, excellent fabricability and oxidation resistance; ability to withstand low cryogenic temperature as well as extreme temperature or around 1800°F (982°C). |
High-pressure ducting: High-pressure ECS ducts, EBU bleed starter ducts and APU inlet ducts etc. |
|
Titanium & Alloys (Ti CP40 and Ti CP70) |
Has low density (4.5 as opposed to 8.5 for the Inconel family) combined with high temperature resistance. |
Suitable for medium pressure and temperature applications. |
|
Composites & Aluminium |
Light weight, corrosion resistance, and ability to develop complex parts. |
Most preferred materials for the low pressure ducting such as, flight deck air distribution, flight deck instrumentation cooling, avionics ventilation, cabin recirculation, and air- conditioned supply. |
|
Stainless Steel, ex. CRES 321 |
Extreme durability and longevity; corrosion resistance, 100% recyclable etc. |
High-pressure ducting: Engine bleed air ducting system |
The aerospace ducting market is highly dominated by Nickel alloys (Inconel) with almost half of the market share, followed by Composites, Titanium alloys, Stainless Steel alloys, etc. (in decreasing order of market share).
Composites are likely to experience the highest growth with a 7.5% CAGR from 2019 to 2024, owing to galloping demand in low-pressure applications. Composites are expected to gain traction in high-pressure applications as well, such as APU inlet, ECS inlet plenum, and APU plenum.
This rise is also due to rapid innovations in composite products. AVS-SYS Ltd, AVS-SYS Ltd, launched low pressure flexible ducting and new carbon composite ducting for air distribution system respectively, both offer significant weight reduction with enhanced properties. In 2015, Stratasys launched 3D printed air duct which offered design flexibility, weight & cost savings and improved lead times. The cumulative result of many factors is pushing the growth of composite aircraft ducting market.
Alloys of Stainless steel & Aluminum are expected to lose market share during the forecast period. Composites are replacing Aluminum in low-pressure applications, whereas Titanium alloys are replacing Stainless Steel alloys in high-pressure applications.
Nitty-Gritty of the Aerospace Ducting Market
Stratview Research, after putting all the germane factors, favourable factors as well as the constraints, in perspective, estimates that the market will grow at a modest rate of over 5% and shall reach a market value of over US$ 3.5 billion by 2024.
North America rules the roost with around half of the share of the market, followed by Europe and Asia-Pacific.
The global aerospace ducting market is moderately competitive with more than three dozen players active worldwide. Top 5 players, Eaton Corporation, Senior Plc, PFW Aerospace GmbH, Arrowhead Products, and Triumph Group Inc. accounted for approximately half of the market in 2018.
The ducts used in an aircraft are either rigid or non-rigid. The rigid ducts are used throughout the aircraft, from the engine through the fuselage to the wings. Rigid ducts dominate the market, followed by semi-rigid ducts and flexible ducts. Semi-rigid ducts are ideally befitted for the application in complex duct geometries and are generally made up of reinforced composites. Flexible ducts are generally made up of urethane/nylon for low-pressure applications and silicone or metals for high-temperature applications.
The aircraft ducting finds maximum application in the airframe. It alone accounted for half of the total market in 2018, followed by engine applications. The key ducting applications in an aircraft airframe are environment control system (ECS), thermal anti-ice ducting system on wings and tail, bleed air ducts on APU, avionics ventilation, air-conditioning supply, window demisting, flight deck supply, flight deck instrumentation cooling, fuselage insulation, cabin sidewall riser, and cabin recirculation.
The aircraft engines also have many ducting applications like Bleed air ducts, anti-ice ducts for engine cowls, exhaust ducts and pylon ducts.
The continuous developments in turbofan engines with high thrust requires an efficient ducting system which can withstand greater temperature, pressure and distribute air along with fluids, proficiently.
The Growth Bulwark
The growth of duct market will be supported by increase in revenue per passenger per kilometer, which has been growing handsomely in the last five years and expected to keep growing.
The growth is also reinforced with increasing aircraft deliveries which are expected to reach approximately 2,184 units by 2023, mainly driven by demand from the Asia-Pacific region. The continuous organic growth in the production of commercial and regional aircraft is likely to create a healthy demand for ducts.
The global commercial aircraft fleet is expected to grow at a healthy rate over the next five years to reach 29.2 thousand units by 2023, this is a big boost to the duct market.
Continuous developments in high thrust aircraft engines are pushing the industry stakeholders to redesign their ducting systems, roping in advanced materials with the ability to withstand higher temperature and pressure. The use of expensive materials will result in the growth in the duct market in terms of value.
The 787-No-Bleed Disruption
In a departure from the usual practice of using pneumatic systems and bleed manifold, Boeing 787 chose to side with no-bleed system architecture.
Hitherto, the air has been used to perform various functions in an aircraft, for e.x. Cabin air conditioning, for providing initial torque to help start the engine, maintaining proper potable water pressure obviating the use of a pump, operating hydraulic pumps, maintaining cabin pressure, Boundary Layer Enhancement for military aircraft etc. In Boeing 787, the source of power for most of the activities i.e. bleed air has been changed to electric power. In Boeing 787, most of these functions like air-conditioning and wing anti-ice systems, have been facilitated by electric power. There are various advantages of the new n0-bleed architecture, as shared by Boeing, such as:
- Improved Thrust: The bleed air is taken out from various stages of engine, which reduces the net engine thrust. No-bleed architecture, on the other hand, does not need pneumatic support, all of the high-speed air produced by the engines goes to thrust.
- The no-bleed architecture allows significant simplification in engine buildup due to the elimination of the pneumatic system and associated pre-coolers, control valves, and required pneumatic ducting.
- Reduced maintenance costs, due to elimination of the maintenance-intensive bleed system.
- Expanded range and reduced fuel consumption due to lower overall weight.
- Improved reliability due to the use of modern power electronics and fewer components in the engine installation.
- More than 50% reduction in mechanical complexity of the plane and lesser requirement of the ducting system due to the removal of various parts from the engine and airframe of the aircraft like Heat shields, Overheat monitoring systems, Duct burst protection systems etc.
The only remaining bleed system on the 787 is the anti-ice system for the engine inlets. The copious advantages, apart from the 3% expected improvement in fuel efficiency alone, build a strong case for the new no-bleed architecture.
The road ahead
With a seemingly resilient growth in the aircraft industry, the aircraft duct market will also grow in tandem. Cost reduction, cracks in the ducts, galvanic corrosion, de-bonding are a few major issues beleaguering the aircraft duct industry, but recently a major development seems to be a greater cause of concern. As the introduction of the no-bleed architecture which uses more electrical power is of relatively new origin, it would be interesting to observe its success and how fast the industry seems inclined to incorporate this radically different system, as more battery power will force the use of Li-Ion battery which have few issues of their own. Leaving aside this issue the market seems robust and growth can be expected to continue impressively in the near future.
