The demanding needs of wheels & brakes
Wheels and brakes always have and always will be among some of the most frequently serviced aircraft components due to their excessive use and wear. New technologies keep emerging, regulations changing, and harnessing information gained in material science leads the way to current and future trends. The cause for all that is simple: people’s need to fly and travel. It is the main reason for market growth as well. My thoughts follow in hopes of giving some insight into what are and could be wheels’ and brakes’ nearest developments.
Demand for brakes directly depends on worldwide passenger traffic, overall cargo amounts and on any changes in the above mentioned areas. As there is steady growth worldwide in air passenger traffic and carriers’ fleet sizes, it also increases the amount of serviceable and maintained components, including brakes.
A report on aircraft brake systems’ market situation states that carbon brakes will account for the growth in the brakes segment of the aircraft brake system market. This can also be seen at Magnetic MRO, where the majority of brake systems that goes through our workshop are carbon brakes.
Carbon brakes (e.g. Messier-Bugatti-Dowty) are very common. Their usage is increasing in the industry as the time between maintenance events for carbon brakes is approximately 1500-2000 cycles, compared to 1100 cycles for steel brakes. Provided it is important to reduce weight then carbon brakes are preferred, but if a company needs to lower costs then steel brakes should be used.
All-electric braking systems’ extensive usage in landing gear is still in the future, but it’s already aiming at the shortcomings of hydraulic braking systems. They are quite expensive, but very durable. Electric braking systems are used, the extent of it depending on the manufacturer and/or aircraft type. For example, the Boeing 787 has electric brake actuators.
But as it is with everything, all new systems and solutions have to pass testing and receive certification. Certification should be always very stringent as it is the last document that will be released for the specific component after servicing.
Moreover, if components are released with certificates, it is certain that it can be used in the way the certificate is released. Before the certificate release, various tests should proceed depending on the condition of the component and customer needs. Being in accordance with the manuals of the original equipment manufacturer sets everything!
As certification is kind of an ID for a component, the way to test a component before being given a “clear pass” is not always specified. Component testing is carried out according to manuals, but the troubleshooting process is not always straightforwardly specified and may need some creativity from the technician.
Testing itself is very precise. A component will not pass a test as long as there aren’t any deviations from the allowed limits. In such a way, a component can be tested until it meets all the standards and regulations required to be granted a certificate. The number of tests is highly dependent on a specific component and so varies case by case.
At Magnetic MRO we release certificates only when all is clear with the component concerned and it passes all tests. Performed tests are all in limits and in accordance with the CMMs.
But getting back to wheel and brake maintenance, they need a lot of attention after passing testing and receiving the necessary certification, as they are crucial to landings. They need to be serviced at a specific interval and also according to regulatory rules (like all other components), demanding the management of servicing and inspection to be as punctually in accordance with flight times as possible.
Climate and environmental conditions such as a wet, sandy or snowy runway play a big role in the state of wheels and brakes and how often they should be serviced. In addition, there’s also the human factor – flight officers’ conduct with landing gear. All of the abovementioned contributes to the landing gear lifecycle, sometimes not in accordance with planned activities, but as unplanned maintenance. That challenges operators and also MROs to be able to react to changes (e.g. in case of an unforeseen AOG) as fast as possible.
In peak season, timing for MROs needs to be very precise, as otherwise there will be AOGs for operators due to an MRO not delivering components at promised turn-around times. That halts being on time and the cost-loss ratio both for the operator and MROs: all MRO problems are also operator problems. Especially stressful times are peak seasons, when human-factor errors are most prone to occur.
As mentioned previously, carbon brakes already mostly replaced steel brake systems in the 1990s, and before that steel brakes were used for over 50 years. Electro-hydraulic systems are becoming more and more common, so there is a definite trend as it is more precise than “old” hydraulics.
Composite usage may contribute to lessening heavy overhauls as composite materials have a better life expectancy, are more cost effective, and do not add to aircraft weight as much, unlike more traditional materials (such as aluminium).
Another point is keeping up with operators’ needs: MRO responsiveness and adaptability to change with demand. This is obviously not only tied to landing gear technologies. However, as brakes and wheels are components with such great maintenance requirements, MROs have to have the ability to adapt to changes rapidly and adopt a mentality of training staff for what operators need in order to provide service to a wide variety of operators’ wheel and brake assemblies. Our workshop has adopted the responsive mentality, and also the knowledge of offer different capabilities for wheel and brake assemblies exactly where customers’ needs lie.
In the fast developing business area you always have to go with the current, or better yet – swim ahead of it – so we will see what the future will really bring us. One thing of course is guessing, but another is reality.
As Richard Branson once said, “Every success story is a tale of constant adaptation, revision and change.” Keeping that in mind, all technological innovations may bring something new to aviation.
 “Aircraft Brake System Market by Component (Braking Systems (Sensors, Transducers, Actuators, Valves, and Others), Brakes, and Wheels), Fit (Line-Fit and Retrofit), Platform (Commercial and Defense), Region – Global Forecast to 2022″, http://www.marketsandmarkets.com/PressReleases/aircraft-brake-system.asp (31.07.2017))