Aerospace landing gears continue to remain significant in aircraft safety and maintenance
By Saloni Walimbe, Research Content Developer at Global Market Insights (GMI)
PUNE, India - The demand for global connectivity has been growing steadily over the years, in turn driving up the demand for air travel. Rising disposable incomes across the globe, as well as escalating consumer propensity towards global exploration are the major contributors to this. Studies by International Civil Aviation Organization (ICAO) have shown that in 2017, over 4.1 billion passengers were carried by airlines on scheduled flight services, a number that is expected to reach over 4.72 billion by 2020, setting a new record of scheduled airline passengers.
The numbers are indicative of a massive transformation taking place across the aerospace sector. In order to accommodate the ever-mounting demand for air travel, aircraft, component, and engine manufacturers are working tirelessly towards keeping production lines busy to reach record-breaking manufacturing levels. At the rate the industry is progressing, it has been estimated that the global aircraft fleet is likely to reach an appreciable mark by 2028.
A direct consequence of this rise in aircraft production is a surge in demand for robust airline parts and components. One of these components is the aerospace landing gear system.
The origins of the aerospace landing gear market can be traced back to the early 20th century. In the early years, landing gears comprised of skids with wheels added to them. These systems did not have much in the way of security, however, as they would soon become the cause behind many wrecks, due to their breaking on impact from hard landings.
The earliest known version of the now-common retractable landing gear system was the one developed in 1911 by Glen Curtiss for his Triad airplane. The amphibious aircraft, the first of its kind, was able to take off and land on water due to these retractable gears.
This feat kicked off a series of developments in landing gear technologies by the 1930s, with various versions being develops for a range of aircraft models, ushering in a new era of speed and efficiency for the aerospace domain.
Importance of landing gear systems in aerospace applications
One of the most prominent technological feats in the aerospace industry is the landing of a commercial aircraft. The developments that went into this achievement were revolutionary, as landing a plane requires compliance to a number of parameters. For instance, to land safely, plans must descend from heights of over 35,000 feet to the ground and slow their speed from some 650 miles to 0 miles per hour, whilst placing the entire weight onto a system of wheels and struts.
To facilitate this, this system, also known as the landing gear, must be strong enough to carry the weight of the aircraft, while being completely retractable to ensure a smooth flight.
Aircraft landing gear systems are an integral part of an aircraft. Indeed, landing gears have been hailed by many as mechanical marvels. According to reports by Airbus, these systems account for over 7% of the total weight of the aircraft and represent nearly 20% of the overall maintenance costs, which positions them as significant components of an efficient airline.
Landing gears are components which are designed to hold high loads during aircraft landing without incidents of damage to the aircraft or disturbance to passengers. These systems are also designed to carry the entire weight of the airplane while grounded.
Types of landing gears and their components
Aerospace landing gear systems, also known as the undercarriage, are a complex combination of various structural components. These include energy absorption equipment, brakes, tires and wheels. They also include components like retracting mechanisms and steering devices, among others.
Different aircraft feature diverse aircraft landing gear types, depending on their requirements, like floats, wheels, skis, skids or pontoons. Of these, the skids type of landing gears is used often in balloon gondolas, helicopters and tail dragger aircraft. Skis type landing gears demonstrate great potential in aircraft that frequently land or take-off in snowy areas or frozen water bodies. In aircraft that operate on water surfaces, the pontoon type landing gears are used.
There are also different wheel arrangements for landing gears of different aircraft. These include the tailwheel, tandem and tricycle type landing gears. Tricycle landing gear is used extensively in single aisle passenger airplanes including the Boeing 737 and the Airbus 320. In this type of landing gear, the system is arranged similar to a tricycle, i.e. with a single nose wheel located at the front and two sets of bigger wheels located under the wings.
While ground and landing activities are highly reliant on the aircraft landing gear, the plane is in the air, and it is essentially a dead weight. This makes it highly important for the landing gear system to be stowed inside the aircraft to reduce unwanted drag, so as to ensure optimum aircraft performance. There are two types of landing gears on the basis of retraction – the fixed landing gear, which hangs beneath the aircraft even during flight, and the retractable landing gear, which gets stowed within the aircraft during flight. All modern aircraft use the retractable aircraft landing gear type.
A common challenge of aerospace landing gears and how to solve the same
One of the common landing gear problems creating research interest among aeroacoustics and aeronautical engineers is its robust contribution to high levels of aircraft noise, especially during landing.
Excessive noise is considered to be an active danger to public health. High levels of occupational and environmental noise lead not only to auditory disabilities, but epidemiological research has revealed that it is associated with many other short and long-term health issues, including cardiovascular conditions, tinnitus, sleep disturbance, and even cognitive impairment in children. In fact, the WHO has estimated that nearly 1-1.6 million health life years in Western Europe may be lost annually due to environmental noise.
Noise generated by landing gear, particularly at approach, is a major contributor to aircraft noise pollution. It has been observed that nearly 30% of the total noise generated during landing is generated by landing gear systems. This noise is caused predominantly due to vortex shedding and flow separating from various struts, dressings and joints that are exposed directly to the incoming air flow.
Considering the level and potential impact of this noise, it has become necessary to implement various noise reduction measures. A number of technologies have emerged to date, with some undergoing lab tests and even flyover tests.
To streamline the approach and landing processes and ensure a smooth and event-free landing, the German Aerospace Center has developed a system called the LNAS (Low Noise Augmentation System), which is designed to support pilots in performing complex tasks necessary for a low-noise approach.
The system includes a display located in the cockpit, which can help the pilot visualize exactly what task is to be performed at what time, to enhance efficiency and reduce noise. The German Aerospace Center has undertaken this project as a joint effort with the Swiss Federal Laboratories for Materials Science and Technology (EMPA) and the Swiss SkyLab Foundation.
Recent strategic maneuvers and innovations in the aerospace landing gears industry
In an effort to develop innovative landing gear technologies and facilitate more streamlined flight activities, aerospace landing gear industry players are undertaking several strategic decisions and working together with researchers and important entities in the aerospace sector.
For instance, Saab and Boeing have chosen Collins Aerospace as the preferred business to provide two pivotal systems for the T-X Trainer. Collins is a company formed by the merger of UTC Aerospace Systems and Rockwell Collins, following United Technologies’ acquisition of Rockwell in 2018. The company has been tasked with delivering a fully integrated landing gear system for the aircraft as well as its ACES 5 pilot escape system. The landing gear comprises of actuators, structure, hydraulics, dressings and brake/wheel assemblies.
Collins has also collaborated with Lufthansa Technik AG to develop a licensing and asset agreement, the first of its kind, designed to enhance MRO (Maintenance Repair and Overhaul) services for the Airbus A380. Under the terms of this agreement, which is valid throughout the A380 program lifespan, Lufthansa will have the ability to offer MRO services for landing gear systems as well as access to other assets in order to support customer layover schedules.
One of the best ways to ensure optimum landing gear performance is weight reduction. To that end, many manufacturers and industry players are making significant strides in developing lightweight, durable, sturdy materials at economical process in order to replace the conventional steel and titanium alloys used currently, including even composite materials used in some landing gear components.
For instance, composite materials are being widely used in the construction of nose and main landing gear doors for various prominent airliners including Airbus A310-300, A320, A330, etc. as well as Boeing B767 and B777. In the B787 main landing gear, carbon fiber braces are utilized.
A lot of time, energy and effort is being implemented in the research and development of new landing gear technologies and products. In consequence, this is likely to pave the way for the next generation of aircraft landing gear systems that are quieter, lighter, more durable and more cost-effective.
 Global Market Insights Inc. has a market report dedicated to global aerospace landing gear systems, available at:
https://www.gminsights.com/industry-analysis/aerospace-landing-gear-market
