Washers, an important part for weight distribution in many machines, are thin, disc-shaped plates with a hole in the center. Though they are commonly metal, washers come in a variety of materials and are used as spacers, springs, pre-loading screws, and vibration reducers. Washers come in three types: plain, spring, and lock. This blog will explore each type and provide insight to their characteristics and applications.
Plain washers are used to distribute loads to larger areas and prevent damage to assembled surfaces. Within the subset of plain washers, there are flat washers, fender washers, shoulder washers, and countersunk washers. Flat washers are the standard plain washer, a thing, flat, circular piece with a hole in the center. They are used to distribute loads and provide support to head fastener screws. Fender washers are similar to flat washers, but the central hole has a much smaller diameter than that of a flat washer. Shoulder washers have a shoulder-like structure and are used to insulate screws, wire or other assembly parts. They come in fiberglass, phenolic, nylon, as well as PCTFE and PTFE metals. A countersunk washer has a 90 or 120 degree countersink in its center. These washers work well for countersunk screws and provide a flush surface to countersunk screws.
Spring washers operate during vibration or shock to provide axial load relief to whatever they are affixed to. Like plain washers, they come in many subtypes such as conical, crescent, and dome spring washers. Conical washers are used to keep assemblies tight in instances of thermal expansion or contraction. Crescent spring washers provide a constant spring rate over the deflection range and have unique applications in flexible load-cycling products. Dome spring washers are curvaceous to create a spring load-bearing surface, providing them with a very high load capacity with a small deflection range.
The third type of washer, the lock nut bearing, is a variation of the spring washer. Their purpose is to prevent loosening by minimizing rotational unscrewing. Tooth and helical lock washers are the main types of lock washers, each with unique capabilities. Tooth lock washers, whether external or internal, use teeth to prevent nuts or bolt heads from loosening and absorb shock and vibration. Helical spring lock washers provide protection against loosening during vibration and corrosion by increasing the preload on a screw when it is tightened.
Like with other industries, there are some interesting secrets and tidbits of information in the aviation industry that only those working within the industry know about. In the same way that only Disneyland employees know how the magic happens, so too do flight attendants, pilots, and others who claim that territory have their own set of secrets that they keep. Read on below to get a glimpse into those secrets.
While the following fact may not be applicable on all commercial aircraft Instrument, it definitely holds true for some, including the famous luxury airline KLM. KLM and other airlines will never have a row labeled with the number 13, as the number is very commonly associated with bad luck and ill fortune. So while an aircraft may have more than 13 rows and while your boarding pass may be numbered 13B, don’t be surprised if you can’t find that number on the seat map or while boarding. Similar to how some older hotels will simply skip over Room 13 and move from 12 to 14, so too will some airlines skip over Row 13 to avoid having the number on the plane.
If you’ve looked closely enough at the front of the aircraft, you might notice that there are actually wipers on the aircraft cockpit windows. Look even closer and you’ll see that the windows can even open. If you’re wondering what’s the need for the windows to open, it’s only there as an extra precaution if the pilots have made a detoured landing and the pilots are unable to exit via the mandated route. The wipers, believe it or not, are actually used for wiping away snow or rain on the windows, though they are not always found on every aircraft, since most modern aircraft will have hydrophobic coating on their windows that affects the surface tension of raindrops and creates a kind of see-through film on the windscreen which is super beneficial for the pilots’ ability to see.
As an aircraft with a basic engine rises in altitude, the amount of power that the engine can produce by itself decreases. Aircraft engine control power is created through the mixture or air and fuel, and the higher the altitude, the lower amount of oxygen is present in the air. While making an engine bigger to pull in a greater mass of air may seem like a good solution, it will cause the aircraft to be much bulkier and heavier, and it does not efficiently tackle the core of the problem which is oxygen density. The solution to this problem came with the introduction of the turbocharger.
A turbocharger is a component that is utilized to turn engine waste exhaust into more power through the use of forced air. The gasses from the engines exhaust are brought into the inlet of the turbocharger and spin the turbine within. This air is then compressed in great quantities before being cooled and sent back to the engine cylinders for more power generation. Through a turbocharger, the mass of air that enters the cylinders is increased with each intake, greatly increasing performance.
By compressing air, smaller engines are able to produce much more power through fuel combustion, making them generate equal power to their counterparts of greater size. Within aviation, this allows for smaller engines to be able to perform well at higher altitudes by creating more oxygen dense air for combustion. Cars, trains, and other engine based vehicles also see increased performance with turbochargers. Through creating smaller engines that increase power through exhaust, better fuel economy and reduced emissions is also possible. Turbochargers also have the added benefit of being more quiet and smooth as compared to standard engines through the refinement and filtering of air as it passes through the turbocharger and components.
Aircraft are, without question, very complicated pieces of machinery. The process of producing one can seem overwhelming and practically impossible. However, when you break it down to its basic steps, the production of an airplane is easy to understand. The three steps of aircraft production are design, construction, and assembly.
The first step in producing an aircraft is the design stage. This is the time when the objectives and specifications are established. Most companies use computers to plan the design, creating drawings and equations to test the abilities of the aircraft. After this comes a series of rigorous simulations to test the specifications of the aircraft. In this process, computers simulate the performance of the aircraft and small models are built to test in wind tunnels, giving an indication of the plane’s aerodynamic tendencies.
Once design is complete, the next stage is construction. Each aircraft is made up of a number of components, and each component is made of thousands of parts. Because of the complexity and importance of proper construction, the process must adhere to strict regulations and standards. While there are only a few major aircraft manufacturers, the construction process often involves many other companies responsible for making parts and components for use in the aircraft.
After construction of the many parts and components, they are inspected and sent to the production line. This is where, at last, the final stage of assembly can take place. Frequently a plant will have separate production lines dedicated to certain parts of the aircraft, such as the wings or fuselage of large planes. After all the parts are assembled and inspected, the plane embarks on a series of flight tests ensuring the performance of the plane is tip-top. Upon completion of these tests, the plane is ready for its final touch ups including internal configuration or cosmetic work. From here, the airplane is sent to the customers and is ready to take to the skies.
If you own a car and live in climates that go below freezing, then you’re more than likely aware of the burdens of de-icing your car. For those residing elsewhere, it's not something that you have to think about...unless of course you own and operate an aircraft. If you are based in a place with temperatures like that of sunny California, owning an aircraft means you have to get familiar with the process of de-icing your aircraft and understand its important role in aircraft maintenance.
When an aircraft takes off, it’s not unusual for it to land or pass through freezing temperatures. This will sometimes result in the surface of your aircraft receiving some frost. For the tougher segments of frost, it is crucial that you take time and training to learn how to properly defrost. Learning the correct procedure can prevent any potential mishaps or bumps in your journey.
One method is to apply Type 1 de-icing fluid to your aircraft’s surface. This fluid, usually a mixture of water and propylene Glycol, is mixed and heated to a temperature around 180 degrees. A altimeter is then used to measure the fluid’s freezing point to determine if it’s safe to use on the aircraft. In most cases, you’ll be done, but if the current climate is experiencing falling precipitation, then it is necessary to apply type 4 fluid as a second coat of de-icing. This second coat will protect the plane during its take off phase and is exclusively applied only after Type 1 has been used.
Investing in the correct de-icing solutions and using the proper procedures to apply them to your aircraft will not only melt away any frost on your vessel, but it will ensure that your aircraft is safe and fully prepared to take flight even in the coldest conditions. If you’re looking to source certains aircraft parts and accessories to maintain your aircraft, you can trust that the team at ASAP Sourcing Solutions has the knowledge and inventory!
When you’re in flight, the only thing separating you from the thin air outside is an airplane window. On one side, there’s a warm, pressurized cabin where you can work, watch movies, sleep — and on the other, air that is not suitable to breathe. Between the two, incredibly sturdy windows. Aircraft cabin windows and windshields are designed to withstand high pressure environments that normal windows couldn’t function in.
A cabin window consists of three panes: an outer pane that is flush with the outside fuselage, an inner pane which has a pressurization hole in it, and a thinner, non-structural plastic pane called a scratch pane. Passengers can’t touch the inner pane or the outer pane for safety reasons; instead, passengers can rest their weary heads against the scratch pane. The scratch pane isn’t actually part of the window assembly itself but installed separately.
As your aircraft gains altitude, the pressure acting on the outside of the plane drops; the air is much less dense the higher your plane climbs. Because aircraft cabins are pressurized to about 6,000 feet for passenger comfort, there is more pressure inside the plane than acting on it from the outside. That pressure is pushing against the fuselage and the cabin windows. The little hole on the inner panel allows some of the cabin air to escape into the pocket between the inner and outer panes and equalize. This forces the outer pane to take all of the load, albeit slowly. The small hole is designed to function so that as the plane ascends the pressure slowly equalizes for aircraft engine control.
The inner and outer pane thickness is specific to each type of aircraft. Inner panes are generally thinner at approximately 0.2” thick and are only present as a fail-safe if the outer pane fails. The outer panes are thicker—at approximately 0.4” thick—and carry the pressure loads for the life of the window. The increased thickness is meant to allow for engagement with the airframe structure while maintaining the required strength. The air gap is approximately 0.25” and also varies for each aircraft.
Aircraft cabin windows are not made of glass but with a material referred to as stretched acrylic. It’s a lightweight material manufactured by a few global suppliers for the various aircraft flying today. One such supplier is UK-based GKN. The largest manufacturer of cabin windows worldwide, Hawker Beechcraft makes cabin windows for the Boeing 737 and the Boeing 787, and most other aircraft. Stretched acrylic is produced by stretching the base material of as-cast acrylic, and provides better resistance to cracks, reduced crack propagation, and improved impact resistance.
Another type of window that exists on aircraft is the windshield/cockpit window. It consists of a toughened glass pane, a heating/deicing element, a vinyl layer, surrounded by another layer of reinforced glass. Airliners utilize acrylic as well due to its versatility. The cockpit windows are thicker and stronger as they have to withstand bird strikes—which aren't an issue on the sides of the fuselage where the cabin windows are. Jet windows are also made of stretched acrylic but are a single layer in a far more complex curved form.
Also referred to as a “bleed” or “breather hole”, those tiny holes at the bottom of the airplane windows parts actually have a purpose. Airplane windows are thicker and stronger than they may appear, and for a good reason.
In order to keep airplane cabins windows relatively comfortable, a pressurized atmosphere allows for proper breathing and comfortable temperature. What makes this possible while still being able to watch the skies around you is a three-layered window, made to equalize the low pressure outside and the high pressure inside.
Each layer of the window has a specific function to make the system work. The outside window, on the exterior of the plane, is 12mm thick. It serves as a protective layer to keep the outside air out, being the most structurally sound layer. The middle layer is 6mm thick and contains the bleed hole. This hole ensures balance between the high-pressure cabin and low-pressure atmosphere outside. The innermost layer, on the interior of the plane, is 4mm thick, and acts as the insulated barrier. Also known as the scratch pane, is a protective layer to prevent the passengers from feeling the cold temperature outside while the plane is at cruising altitudes.
Now the little bleed hole that some people may never notice has an important function. As we already mentioned, it helps neutralize the pressure inside the cabin to make it comfortable for customers, but it also helps release moisture. This helps prevent fog and frost from building up on the inside of the window. If you have ever noticed that frost may build up slightly in a round pattern, it is the combination of window surface temperature, cabin humidity, and rate of air flowing through the hole.
If there was no bleed hole, there would be unequal pressure in the cabin and outside the aircraft. This can lead to the windowpanes breaking. With the ever-growing technology, airplane windows may not need this bleed hole. The newest plane that does not have this tiny hole is the Boeing Aircraft 787.
The Federal Aviation Administration requires that all aircraft have ice built up on their wings and fuselages stripped off before takeoff. This is because ice, if not removed from the aircraft’s engine control surfaces, can negatively affect the handling characteristics of the aircraft and pose a safety hazard.
The best method for deicing an aircraft is simply to heat it up. Heated hangars can be kept at a temperature that melts ice, whereupon it can be wiped away with a towel. Afterwards, a thin coating of freezing point depressant (fluid) is applied to the aircraft’s wings to prevent ice from forming again during takeoff and flight. However, this space is often at a premium, and some smaller airports may not have any heated hangars available at all.
Another option for preventing ice buildup is using aircraft covers designed to shield the wings and other components vulnerable to ice build-up. These covers also have the advantage of being easy to store, and relatively inexpensive. However, icing can still occur between taking the covers off and take-off, so applying FPD liquid may still be necessary.
The final and most common method for deicing aircraft is using spray equipment that applies FPD liquids to the plane. Most airports provide portable spray equipment like pressurized containers and spray wands to apply de-icing liquid, which consists of ethylene glycol and propylene glycol. As the FPD melts ice however, it mixes with the water and dilutes. If the aircraft is on the ground for extended periods of time and waiting for takeoff, it may be necessary to apply additional coatings of FPD. Glycol is also toxic, much like the antifreeze in automobiles and refrigeration equipment, so safety precautions must be taken to prevent exposure.
We know that an aircraft bearing component is quite important in aviation, but let’s take a look at another industry— wind energy. Wind turbine technology is on the rise as more U.S. companies look to invest in renewable energy. Bearings are an important component used in wind turbine operation, and they are often utilized in the main shaft. There are two integral bearing variations that you will come across within the main shaft of a wind turbine— spherical roller bearings and tapered roller bearings.
Spherical roller bearings (SRB) are usually used in single SRB designs, where a 3-point mount system is supported by one main bearing. Because the main bearing can take some of the load, two torque arms are designated to carry gearbox reaction stressors and loads. Failures of this mechanism occur because of two occurrences—application of too much thrust, or inadequate lubricant generation. Regular maintenance concerning the former issues is extremely important, as full replacement of a main shaft and its bearings can cost upwards of $450,000.
Tape bearings (TRBs) are designed to improve the powertrain performance of the turbine. They are engineered to provide increased stability to the main shaft through a load sharing construction of rows, and predicted roller-to-race interactions. There are three main types of TRBs, including: widespread single TRBs, large diameter TRBs, and single preloaded TRBs.
A widespread single TRB is considered economic in design because of its compact size and its ability to preload a whole turbine system using just two TRBs. The system can adjust bearing capacity through an upwind and downwind series. These components act like bookends to the widespread center between the two bearings. The series manages applied load by adjusting the contact angle when necessary.
A large diameter TRB, sometimes referred to as a TNA bearing, is most often seen on direct-drive wind turbines. It is known for its easy set up and has excellent ratings for field performance. This component utilizes a spacer unit that is placed between two cone races at a steep angle. The angle of the cones creates what is called high tilting stiffness within a compact axial design, allowing the turbine manufacturers to reduce overall nacelle length if necessary.
A single preloaded TRB can manage higher radial loads and thrust loads than an SRB. It utilizes two bearing rows in order to evenly distribute load sharing. Because of its design, this mechanism is able to accommodate higher load capacities and has the capacity to tolerate greater system misalignment.
Jet engine technology has revolutionized global air travel since 1949. The British Overseas Aircraft Corporation (BOAC) introduced the world’s first commercial jet airliner, the Comet 1, which took its maiden flight on July 27th, 1949. It was followed by the iconic development of Pan American Airlines, whose transatlantic routes sparked the beginnings of the competitive aerospace market we know today. In celebration of the jet engine’s evolution, let’s take a look at five fun facts about modern commercial aircraft engines and also look at the how Aircraft engine control.
What is the most widely used commercial engine?
Turbofan engines are the most common propulsion system utilized for commercial aircraft. This type of engine has 4 integral parts: turbofan, compressor, combustion chamber, and turbines. They also contain Aircraft Engine Valvetrain parts.
What is the most powerful commercial jet engine?
The General Electric 90-115 B, which is utilized by Boeing’s 777- 300 ER, holds the Guinness World Record for a most powerful commercial jet engine. It generates an astounding 115,000 pounds of thrust.
How many hours per day is an aircraft engine in operation?
The average commercial aircraft will spend 16 hours a day in the air. Flight cycles per aircraft vary, but the average flight cycle length is 1.9 flight cycles per day. A flight cycle is a series of stages an aircraft experiences from take-off to landing. Bonus fun fact—we use the term “flight cycle” for birds of flight as well. The term describes the process of flight from the moment they expand their wings to the moment they land.
How much does one aircraft engine cost?
Price per engine varies depending on the market, size of the engine, and thrust provided. Usually, the price of the engine/s is integrated into the total cost of an aircraft. A few popular engine models are the Pratt and Whitney 4056, Rolls-Royce RB211, and General Electric CF6. The aircraft these engines are seen in, and their average price, are listed here in consecutive order: Boeing 747- 400, $5.8 million; Boeing 757, $10 million; and Airbus A330, $11 million.
What is the hottest temperature within an engine?
Any given aircraft engine can reach temperatures of 1400 ? or 2552 ?. This temperature occurs in the combustor, where fuel and compressed air