Aircraft maintenance is the performance of tasks required to ensure the continuing airworthiness of an aircraft or aircraft part, including overhaul, inspection, replacement, defect rectification, and the embodiment of modifications, compliance with airworthiness directives and repair.
Aircraft maintenance in civil aviation employs generally Scheduled maintenance checks or blocks which are packages of maintenance tasks that have to be done on an aircraft after a certain amount of time or usage. Packages are constructed by dividing the maintenance tasks into convenient, bite-size chunks to minimize the time the aircraft is out of service, to keep the maintenance workload level, and to maximize the use of maintenance facilities. At the completion of any maintenance task a person authorized by the national airworthiness authority signs a maintenance release stating that maintenance has been performed in accordance with the applicable airworthiness requirements.
Automated aircraft inspection systems have the potential to make aircraft maintenance safer and more reliable. Various solutions are currently developed: a collaborative mobile robot named Air-Cobot, and Unmanned aerial vehicles from Donecle or Easyjet.
Airbus has indicated that data diagnostics could put an end to aircraft unscheduled grounding for fault repairs around 2025, supported by big data and operational experience. Predictive maintenance, diagnostics and health monitoring could eliminate unscheduled groundings, by making maintenance schedule intervals more frequent to avoid AOGs and the associated operational interruptions, ultimately eliminating them. Data or monitoring can tell that some parts do not need a scheduled check, but a full transition to this model will need much greater experience. With more history, examples and regulatory confidence, the maintenance program and associated manuals could become dynamic documents for each specific aircraft with a maintenance schedule based on the operational history of the aircraft.
Aged landing-gear springs caused a B-2A stealth bomber to skid off the runway during a midnight landing at Whiteman Air Force Base, Missouri, Sept. 14, causing at least $10.1 million worth of damage, an Air Force investigation concluded in March 2022.
The board found the springs had not been replaced for at least 10 years, and may have never been replaced since the aircraft was delivered in 1990. Since 2018, a new policy required that the springs be replaced when B-2As underwent major overhauls. But the “Spirit of Georgia” had not gone through such an overhaul in that time.
The board also listed the failure of a coupling in a hydraulic line — which caused most of the hydraulic fluid in two of four hydraulic systems to quickly leak out — as “substantially contributing” to the mishap. The B-2A is the world’s most expensive aircraft, reportedly priced at $2 billion each in current-year dollars. They are also costly to maintain. The Air Force spends about $18 million per aircraft on maintenance each year, according to a 2020 report by the Government Accountability Office.
US Air Force’s Cloud-Based Aircraft Maintenance Ecosystem
In July 2021, Google Cloud and the United States Air Force Rapid Sustainment Office (RSO) announced an agreement to build an open, agile, and globally scalable ecosystem using Google Cloud technology for aircraft maintenance. Through this initiative—code-named “Project Lighthouse”—the RSO will be able to optimize maintenance readiness, increase staff productivity, and reduce overall costs.
With more than 329,000 active duty personnel and more than 170 operating locations around the globe, the RSO’s goal is to implement and scale new technology solutions that build a stronger, more agile, and more resilient Air Force. Project Lighthouse is a program that integrates successful RSO technology solutions to create a unified ecosystem that helps the RSO accelerate its goals and digitize for the future.
“Our partnership with Google Cloud is a significant milestone for RSO on our journey to adopt Industry 4.0 technologies, when everything is connected, and deliver on our mandate to solve the Air Force’s toughest sustainment challenges,” said Mr. Nathan Parker, deputy, Program Executive Office at RSO. “What we’re building with Google Cloud will accelerate the way we adopt, integrate, and scale technologies for the Air Force. Project Lighthouse is a hardware-flexible, software-driven approach that provides optionality at scale.”
This new aircraft maintenance ecosystem will provide seamless integration for the Air Force’s full ecosystem of technology providers, which could range from predictive maintenance software to manufacturing robotics to augmented reality headset and other hardware. Powered by Google Cloud’s API management platform Apigee, and managed application platform Anthos, this project is supported by Google Cloud’s professional services organization. Before launch, the aircraft maintenance ecosystem will be prototyped, validated, and tested for scalability within the Air Force’s technology environment.
USAF maintenance repairs active flying aircraft using cold spray AM
The 28th Maintenance Group Additive Manufacturing Flight at the Ellsworth Air Force Base conducted its first restoration of an active flying aircraft in May 2021 and repaired an overwing faring slip joint using metal cold spray (kinetic consolidation) technology. The very first demonstration of on-aircraft structural repair using metal cold spray AM technology had been conducted successfully at the USAF base in September 2019.
In this first application on an active aircraft, the slip joint had to be repaired to enable vertical movement within the wing contours, both up and down. In the same manner, of which a hinge holds a door in position as it is opened and closed, the slip joint does a similar job for the B-1’s wings. “During cold spray, we used helium gas to accelerate the particles to a speed of Mach 3,” said Brian James, the 28th MXG additive manufacturing chief engineer. “Upon impact, the particles become the substrate, forming a strong mechanical bond.”
What normally takes weeks or months of time to order, ship and remove the old component and install the new part, can now be done in mere hours or days by using cold spray technology, said James. Annually, the Additive Manufacturing Flight saves the Air Force approximately $2 million. “The only other alternative to fixing the slip joint, if we didn’t use cold spray, would be to remove and replace the part, which would cost roughly $500,000 and [take] 8 weeks to remove,” added James.
For the past seven years, Ellsworth worked alongside VRC Metal Systems, a company that specializes in the manufacturing of cold spray machinery, cold spray-related process work development and research, and development of new cold spray applications for government and commercial applications. During this time, the VRC Raptor Cold Spray machine was developed and helped the base accomplish part restoration historical feats.
The Commercial Aircraft Maintenance, Repair, and Overhaul (MRO) Market was valued at USD 33 billion in 2021 and is expected to be over USD 34 billion by 2026, registering a CAGR of over 1% during the forecast period (2021-2026).
The ongoing COVID-19 pandemic has resulted in a full-scale crisis with the imposition of travel restrictions and suspension of flights in a global effort to contain the spread of the virus. The aviation industry is in survival mode, crippled by the loss of traffic and revenues. According to the latest updates from IATA, ICAO, the Airports Council International (ACI), the UN World Tourism Organization (UNWTO), the World Trade Organization (WTO), and the International Monetary Fund (IMF), the international air passenger traffic in 2020 is expected to experience a drop of about 50-55% as compared to 2020 baseline. Airline Revenue-Per-Kilometer (RPK) is anticipated to drop by 48% compared to 2019 value. The airlines are expected to record potential losses amounting to USD 289 million to USD 387 billion in gross operating revenues. Europe and Asia-Pacific are anticipated to be the worst hit in terms of international passenger traffic and revenues.
Airlines are inclined towards maintaining the optimum health of their fleet and choose to procure new aircraft only as a last resort owing to the high investment required for it. With COVID-19 severely hampering revenue sources and eroding the profit margins of the airlines, more airlines are expected to resort to MRO to maintain fleet efficiency. Furthermore, several government initiatives have been formulated to encourage airports to support MRO as a strategic activity. Various holistic approaches are now being undertaken by the governments to ensure that adequate space is allocated at various airports within the country for MRO, which may lead to an enhancement in terms of commercial aircraft MRO activities during the forecast period.
However, the advent of predictive maintenance has flooded the MRO industry with a flurry of problems, both technological and manpower-related. Since the concept of predictive maintenance powered by innovative technologies such as digital twins is still in its infancy, rapid improvements and growth are visualized within a short span of time. This implies that not all firms are equipped with the required infrastructure to harness the true potential of machine learning and other advanced emerging concepts. This also indicates the limited reach of the concept as comparatively few MRO organizations are keen to invest capital for developing these skills among their personnel, while the domain is not well represented in industry-focused education and training curricula. Moreover, there is limited cooperation between MROs and OEMs pertaining to the repair standards for new equipment and components, which has made the MRO process highly complex and demanding. Such disruptive threats endanger the growth of the market in focus during the forecast period.
Key Market Trends
Engine MRO Segment to Dominate the Market
Engine MRO includes both field maintenance and depot maintenance checks. Depot-level maintenance entails material maintenance along with major repair, overhaul, or complete rebuilding of engines, parts, end items, assemblies, and subassemblies. It also includes the manufacturing of parts, technical assistance, and testing. Field-level maintenance comprises shop-type work as well as on-equipment maintenance activities at levels different to depot maintenance. Intermediate or shop-type work includes limited repair of commodity-oriented assemblies and end-items, job shop, bay, and production line operations as per requirement, software maintenance, and repair of subassemblies such as fabrication or the manufacturing of repair parts, assemblies, and components.
In the engine-maintenance sector, OEMs control approximately half of the market, with the other half roughly split between independent and airline overhaul shops. For new powerplant generations specifically, operators frequently outsource engine maintenance and use full MRO-support programs. For instance, within a span of five months or from June 2017 and October 2017, and after entering into an agreement with Rolls-Royce to service the engines powering the A350s ordered by Air France, Air France KLM’s MRO unit launched support services for the CFM International Leap engines that power the A320neo-family and B737 MAX jets. Such developments are anticipated to drive the engine MRO segment of the market during the forecast period.
Asia-Pacific to Witness the Highest Growth
The commercial aviation industry in APAC is expected to grow at a rapid pace over the next decade in the wake of strong demand for new narrow-body aircraft, which will enhance the need for MRO operations. Countries such as China, Japan, India, South Korea, Singapore, and Australia are significant contributors to the growth of the commercial aircraft MRO market in the region. The commercial aircraft fleet size in Asia-Pacific is estimated to grow from 7,954 to 8,216 during the forecast period, which depicts the rise in demand for MRO services in the region.
The outcome of China’s maturing aviation industry is aging fleets requiring the replacement and disposal of outdated aircraft components. Airline carriers in the country have placed huge orders for new aircraft. For instance, China Eastern Airlines has an order backlog of 20 A350s and 54 B737-8s. Such huge procurements offer greater scope for regional MRO operators in terms of component pooling. Developing countries, including India, project a tremendous scope for MRO operations based on the number of new aircraft orders and the maintenance opportunities resulting from them. For instance, Airbus has a total order of around 500 aircraft in the country and is exploring the possibilities of establishing an MRO unit in the country. Singapore is also expected to achieve a dominant position in the commercial aircraft MRO market. Moreover, low-cost labor markets such as Vietnam and Thailand are getting increasingly attractive to OEMs and MROs for setting up new facilities to cater to growing demand across the region. Such developments are certain to drive the growth of the market in focus in the region.
The commercial aircraft MRO market is highly fragmented, with many players with different MRO capabilities offering services both globally and regionally. TAP M&E, GE, AAR, United Technologies Corporation, L3 Harris Technologies, Lufthansa Technik, and ST Aerospace are some of the prominent players in the market. With the advent of newer generation aircraft, the TBO (Time Between Overhaul) of the aircraft is increasing, which may challenge the existence of the smaller players in the coming years. Presently, the global commercial aircraft fleet has an average age of more than 11 years, which is expected to reduce further in the coming years. As the average age of the aircraft to be maintained decreases, the overhaul costs are projected to decrease as a whole. However, the revenue generated from regular maintenance and repair of the aircraft may continue to increase with the growing fleet.
Top companies include GE, Rolls-Royce, MTU Maintenance, Lufthansa Technik, Pratt and Whitney, Air France/KLM, Snecma, Delta, TechOps, Standard Aero, BBA Aviation, Chromalloy, ITP, Air New Zealand, Bet Shemesh, IAI, Wood Group Turbopower, Sigma Aerospace,
Hellenic Aerospace, Sabraliner, Asia Pacific Aerospace, and Chinese Dragon General Aviation
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