Informative
The Checks Required To Perform Aircraft Maintenance
Airplanes are one of the most complicated machines ever built by humans. People often overlook the sheer level of engineering that goes into manufacturing a metal machine that can sustain flight for several hours, cross oceans, land countless times and repeat the same procedures the next day. When boarding a modern jet airplane, it’s easy to forget that you’re boarding one of the most sophisticated machines ever built. For instance, the Boeing 747 has about 1,000 wire bundles, ranging in length from 2 feet (inside electrical panels) to 120 feet, and comprises more than a million parts. As sophisticated and mesmerizing these machines get, there is a need to take care of them. The maintenance of an airplane is one of the most expensive things to do out there. At times, the maintenance costs can exceed the price of the airliner itself. Crazy right? Let us divide the different checks required while performing maintenance on an aircraft.
Aircraft maintenance checks are periodic inspections that have to be done on all commercial and civil aircraft after a certain amount of time or usage. Military aircraft normally follow specific maintenance programs which may, or may not, be similar to those of commercial and civil operators. They are divided into three types of “checks” that bundle together hundreds of tasks: A Checks, B Checks, C Checks, and D Checks. Here’s a quick summary of what checks happen, and when:
Line Maintenance: This type of maintenance is the most common. During transit checks, things like wheels, brakes, and fluid levels (oil, hydraulics) are inspected. Plus, any ongoing maintenance that the aircraft indicates it needs via thousands of onboard sensors. Line maintenance would take roughly 12 hours per week for most airplanes. These occur all around the world and at all times.
A-Check: Filters will be changed every eight to ten weeks, important systems (such as hydraulics in the aircraft’s ‘control surfaces’) will be greased, and a thorough inspection of all emergency equipment (such as inflatable slides) will be conducted. A normal “A-Check” on B737 takes anywhere from six to twenty-four hours. This type of check is performed approximately every 400-600 flight hours, or every 200–300 flights, depending on aircraft type. It needs about 50-70 man-hours and is usually performed in an airport hangar. The “A-check” takes a minimum of 10 man-hours. The actual occurrence of this check varies by aircraft type, the flight cycle count, or the number of hours flown since the last check. The occurrence can be delayed by the airline if certain predetermined conditions are met.
B-Check: The “B-check” is performed approximately every 6-8 months. It takes about 160-180 man-hours, depending on the aircraft, and is usually completed within 1–3 days at an airport hangar. A similar occurrence schedule applies to the “B-check” as to the “A-check”. “B-checks” are increasingly incorporated into successive “A checks”, i.e., checks A-1 through A-10 complete all the “B-check” items.
C-Check: The “C-check” is performed approximately every 20–24 months, or a specific number of actual flight hours (FH), or as defined by the manufacturer. This maintenance check is much more extensive than the “B-check”, requiring a large majority of the aircraft’s components to be inspected. This check puts the aircraft out of service for 1–2 weeks. The aircraft must not leave the maintenance site until it is completed. It also requires more space than A and B checks, therefore, it is usually carried out in a hangar at a maintenance base. The effort needed to complete a “C-check” is up to 6,000 man-hours.
D-Check: The “D-check”, sometimes known as a “heavy maintenance visit”, is by far the most comprehensive and demanding check for an airplane. This check occurs approximately every 6-10 years. It is a check that more or less takes the entire airplane apart for inspection and overhaul. Even the paint may need to be completely removed for complete inspection of the fuselage metal skin. Such a check can generally take up to 50,000 man-hours, and 2 months to complete depending on the number of technicians involved. It also requires the most space of all maintenance checks, and as such must be performed at a suitable maintenance base. The requirements and the tremendous effort involved in this maintenance check make it by far the most expensive, with total costs for a single “D-Check” in the million-dollar range! This is also known as a C4 or C8 check depending on the aircraft type. the entire aircraft is basically dismantled and put back together. Everything in the cabin is taken out (seats, toilets, galleys, overhead bins) so engineers can inspect the metal skin of the aircraft, inside out. The engines are taken off. The landing gear is removed and overhauled with the aircraft supported on massive jacks. All of the aircraft systems are taken apart, checked, repaired, or replaced and reinstalled.
To put the cost in perspective, on average, it costs up to 5 million dollars to perform a D-Check on a Boeing 777-300ER and about 6 million dollars for a Boeing 747 family. Maintenance may seem like a hassle but this is the only way many airplanes are still flying despite being 25-30 years old.
Sources
- https://en.wikipedia.org/wiki/Aircraft_maintenance_checks
- https://www.qantasnewsroom.com.au/roo-tales/the-a-c-and-d-of-aircraft-maintenance/
- Cover photo: Flightradar24/Jetphotos.net/La Roche Spotters
The adrenaline rush that accompanies the surge of power felt during an airplane’s takeoff is a captivating experience. However, the complexities of aircraft takeoff extend far beyond this initial thrill, deeply rooted in intricate maneuvering and meticulous calculations. This process, primarily defined in terms of Takeoff Distance (TOD), involves two main segments – the ground roll and the airborne distance necessary to reach the screen height of 35 ft. Multiple factors interplay to influence this takeoff distance. Let’s delve into factors affecting takeoff distance.
Atmospheric Influence on Takeoff Performance
The performance of an aircraft is tightly knitted with atmospheric conditions, specifically the ambient temperature. As temperatures soar, the aircraft’s performance correspondingly takes a dip. This phenomenon is attributed to the rise in density altitude. An elevated density altitude impairs both the engine performance and the aerodynamics of the aircraft, necessitating a deeper understanding of the impact of density altitude on aircraft operations.
Another atmospheric factor playing a crucial role in aircraft takeoff is the prevailing wind conditions. Planes predominantly take off into the wind, as a headwind contributes to reducing the takeoff distance, whereas a tailwind tends to elongate it. This is due to the interaction between Indicated Air Speed (IAS), True Air Speed (TAS), and ground speed. If the wind direction and speed are accurately factored into the calculations, pilots can optimize their ground speed requirements, significantly impacting the takeoff distance.
Weight and Its Impact on Aircraft Takeoff
Weight is another factor that plays a major role in influencing takeoff distance. An increase in the weight of the aircraft essentially means an increase in inertia, translating into the requirement of greater acceleration and a consequently longer runway. A weightier aircraft also imposes a higher load on the ground, escalating the wheel drag and friction. This heightened friction, combined with the need to attain a certain speed for lift-off, necessitates a longer runway roll for heavier aircraft, thereby increasing the takeoff distance.
Runway Conditions and their Role in Takeoff
The runway, where the action unfolds, also contributes to the intricacies of aircraft takeoff. The characteristics of the runway surface, such as the presence of water, snow, or slush, can increase the friction experienced during takeoff, affecting the required distance. Similarly, the slope of the runway also plays a part in influencing the takeoff roll. An uphill runway works against the acceleration of the aircraft, while a downslope assists the acceleration, reducing the takeoff distance.
Mitigating Factors: Practical Strategies for Optimal Takeoff
Pilots employ a range of strategies to tackle these influencing factors and ensure a smooth takeoff. One such strategy is the modification of the aircraft’s configuration, such as the lowering of flaps, which can increase lift and reduce the required takeoff speed. However, a higher flap setting also poses its own challenges, emphasizing the need for a well-calculated balance.
Ignoring these factors can lead to a decrement in performance, potentially impacting safety. Fortunately, aircraft manufacturers equip pilots with critical information, such as Weight, Altitude, and Temperature (WAT) charts, to make informed decisions for safe takeoff operations.
Unraveling the complexities of aircraft takeoff and acknowledging the factors that influence it form the backbone of efficient aircraft operation. Such understanding is critical to maintaining the safety and efficiency of flights, particularly in the realm of general aviation, where stringent training and standardization may not always be in place.
READ ALSO: Cleared for takeoff | The take off procedure explained
We’ve discussed the complexities of aircraft takeoff and the factors influencing it. Even as passengers, these aspects shape our flying experience. What are your thoughts on this intricate process? Have you ever noticed these factors at play during your travels? Share your insights or any questions you might have in the comments section below.
Rolls-Royce provides a comprehensive engine management service, TotalCare program, that offers multiple engine maintenance plans to its customers. Jet engines are expensive and critical assets, and to maintain their longevity, operators often seek OEMs and third-party facilities for engine maintenance. The TotalCare program includes predictive maintenance planning, work scope management, and off-wing repair and overhaul activities at various OEM and partner locations. Rolls-Royce’s main goal is to manage engines throughout their lifecycle and ensure maximum flying availability for its customers.
Maximizing Time-on-Wing and Shop Visit Cost Risk Transfer
Rolls-Royce’s TotalCare program offers customers a choice in managing engine maintenance by transferring both time-on-wing and shop visit cost risks back to the company. Rolls-Royce aligns its TotalCare maintenance business model with its customers’ operational model to provide maximum time-on-wing for the engines. The company enhances its internal capability to repair and recycle engine components, allowing for on-wing inspection and repair of several internal and external parts without removing the engine. This approach decreases the need for new and spare parts, and accelerates the maintenance process.
Recycling and Remanufacturing of Engines
According to Rolls-Royce, their TotalCare program can recover and recycle up to 95% of a used engine. Almost half of the recovered materials are of high quality and can be safely remanufactured to create new aerospace components. This approach minimizes the need for OEMs to purchase raw materials, making engine maintenance more sustainable and cost-effective.
TotalCare Engine Management Plans
Rolls-Royce offers three engine management plans through its TotalCare program: TotalCare Life, TotalCare Term, and TotalCare Flex.
TotalCare Life
Under the TotalCare program, customers pay an agreed-upon amount per engine flight hour (EFH) during the engine’s operation, similar to the power-by-the-hour contract offered by many OEMs. Rolls-Royce mandates a minimum term for this plan, and the exact dollar amount per EFH varies based on the customer and usage. If the aircraft and engine are sold to another operator midway between overhauls, the unused maintenance credits can be transferred to the new operator if they also enroll in the TotalCare program.
TotalCare Term
As part of the TotalCare program, the TotalCare Term plan charges an agreed-upon rate per engine flight hour (EFH) to cover expected shop visits for the duration of the agreement. However, if the term ends midway between shop visits, the operator will not have contributed towards the engine life used since the last shop visit. This plan offers a lower rate per EFH, but it limits the services provided within a specific term.
TotalCare Flex
The TotalCare Flex plan is usually used for owned engines that are approaching their retirement age. Under this plan, OEMs offer a complete overhaul to maximize time-on-wing, a partial overhaul that takes the engine to its retirement date, or an engine swap.
Rolls-Royce’s TotalCare program provides a comprehensive engine management service that ensures maximum time-on-wing and cost-effective maintenance for customers. The program transfers both time-on-wing and shop visit cost risks back to Rolls-Royce, enabling customers to concentrate on their core business while Rolls-Royce assumes responsibility for engine maintenance. The program offers three engine management plans, each customized to meet the specific needs of its customers. Through TotalCare, Rolls-Royce aims to encourage more customers to adopt long-term service agreements and reduce reliance on traditional third-party Maintenance Repair and Overhaul (MRO) services.
Also, you might be interested in reading: Jet Engines: How They Work and Power Modern Aviation?
Sources
- Source: Simple Flying
The Solar Impulse 2, a solar-powered aircraft, made history by completing the first circumnavigation of the Earth powered solely by solar energy. Designed by Swiss pioneers Bertrand Piccard and André Borschberg, this innovative aircraft with a wingspan of 72 meters and covered in over 17,000 solar cells showcased the potential of renewable energy in aviation.
The lightweight design, made from advanced materials including carbon fiber, allowed the Solar Impulse 2 to harness solar power during the day and store excess energy in four lithium polymer batteries, enabling it to fly through the night. The aircraft embarked on its journey in 2015 from Abu Dhabi, UAE, and covered over 26,000 miles, with stops in 17 destinations around the world, including India, China, the United States, and Spain.
Despite challenges such as weather delays and battery replacements, the Solar Impulse 2 persevered, highlighting the possibilities of renewable energy in aviation. It had an average flying speed of around 30-40 miles per hour, showcasing that it was not designed for speed, but rather as a platform for promoting sustainability and clean technologies.
During stopovers, the Solar Impulse team engaged in educational and outreach activities, raising awareness about the importance of renewable energy, energy efficiency, and climate change. The success of the Solar Impulse 2 marked a significant milestone in aviation history, inspiring further advancements in sustainable air travel.
In conclusion, the Solar Impulse 2 was a pioneering solar-powered aircraft that completed the first circumnavigation of the Earth powered solely by solar energy. Its lightweight design, advanced materials, and innovative use of solar power showcased the possibilities of renewable energy in aviation. The Solar Impulse 2’s historic journey will be remembered as a milestone in aviation and a testament to the power of human innovation in driving positive change for a more sustainable future.
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