From small generators to large commercial vehicles, every machine depends on fuel to function. Having the ability to conduct fuel calculation of an airplane is critical for crews so that they are able to adhere to set routes. There are a few methods and benefits of being able to measure the amount of fuel that is remaining in an aircraft. Quantity of fuel can be measured with the rate in which fuel is flowing into the engine and can be beneficial for the flight crew of an aircraft to calculate the remaining flight time. Airplane fuel meters and measurements also help for comparing the functionality and performance of engines to past calculated performance.

Depending on the type of aircraft, fuel measurement can differ. For aircraft that are smaller and lighter, a mechanical float assembly dictates an indicator and varies the current flow. The mechanical float is a gauge located in the tank that rests on the fuel's surface attached to an indicating rod. As fuel levels drop, the float operates the indicator to display the remaining fuel. While this method is fairly simple, while the plane is in ascent or descent, it can prove unreliable due to displacement of the floater and fuel. The second method is for high-performance aircraft fuel systems in which the quantity of fuel can be measured in electrical capacitance. Electrical capacitance is the ratio of the change in an electrical charge in a system as compared to the change in its electric potential and enables a more accurate system of measuring fuel.

Both systems differ in their operating principle with one depending on the principle of electrical resistance and the other on the principle of capacitance. Transmitters along with receivers and indicators are the two units of the fuel flow measuring system. For transmitters, they are an electromechanical device attached to the fuel system’s delivery side and create an output signal corresponding to the flow rate. Sensors and transmitters are located in tanks and are connected in parallel for getting average values. The sensors are profiled so that they may give linear output to indicate remaining fuel in the tank. For all fuel quantity measurements, indicators are displayed in either pounds or kilograms.


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Airspeed is the measurement of the speed a plane is traveling on its own, without help from tailwind or other factors. Rather than being measured by an intricate system of electrical parts, airspeed is found using a type of differential pressure gauge called a pitot tube. The tube has an open end which, when mounted on the wing, faces toward the flow of air or water. The airspeed indicator works by measuring the difference between a fixed sensor away from the air stream and a sensor, the pitot tube, in the air stream. While the aircraft is still, the pressure in each tube is equal and the airspeed indicator displays zero.

During flight, the flow of air into the pitot tube causes a pressure differential between the two sensors. This pressure differential is what causes the indicator to move. Air pressure then pushes against the diaphragm that moves a connected mechanical pointer on the speedometer. Each indicator is adjusted to compensate for airwinds to provide an accurate airspeed. In addition to this, most aircraft have electronics to account for altitude and air temperature while calculating an accurate air speed measurement. In the event that the pitot tube becomes blocked by insects, dirt, or other in-flight debris, air cannot enter the system. If this is the case, the system will drop to ambient pressure and the speedometer will read zero.

Because the maximum speed of jet aircraft is measured in knots and Mach, pilots need a speedometer and a Machmeter. A Machmeter measures the ratio of airspeed to the speed of sound called a Mach number. It appears on the Machmeter as a decimal number. The speed of sound is a common standard of airspeed measurement, and is expressed as Mach 1.

At Aerospace Orbit, owned and operated by ASAP Semiconductor, we can help you find all the unique parts for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the Aircraft Instruments and Avionics Parts you need, 24/7-365. For a quick and competitive quote, email us at sales@aerospaceorbit.com or call us at 1-509-449-7700.


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Due to the risks involved in flight, safety measures must be exhaustive, comprehensive, and followed obsessively. Determining the airworthiness of an aircraft is the responsibility of the pilot, flight crew, and the maintenance staff that work on the aircraft. The pilot or copilot is responsible for performing a preflight check, and the maintenance staff is responsible for managing the maintenance state of the aircraft and delivering that information to the flight crew.

The preflight check consists of an exterior walkaround and visual inspection of critical parts of the aircraft, such as sensors, probes, structural components, and exposed motors and cables. This is nowhere near thorough enough to spot every potential problem, but it is still a required part of flight, and has been enough to prevent some flights that should have never taken off from the beginning.

After the walkaround an interior check is conducted with tests of various systems such as fire detection, weather radar, warning lights, and many others. The nature of these tests varies depending on the systems mounted on the aircraft, and some aircraft can conduct these tests automatically.

Maintenance crews are responsible for performing interval checks throughout the aircraft’s lifetime as mandated by the Federal Aviation Administration, referred to as A-checks, B-checks, C-checks, and D-checks. The A-check is the least invasive and must be performed for every 500 hours of flying time. The D-check is the most thorough, occurs every six years or so, and can be so invasive and expensive that some airliners will retire the aircraft rather than deal with it. Additionally, the maintenance crew must keep an inventory of the operational state of all flight safety equipment aboard the aircraft. If the flight crews discover a fault, they need to notify maintenance, who will decide whether to take the plane offline to fix it, or defer it. This decision depends on the MEL, minimum equipment list, that the aircraft needs to adhere to in order to be airworthy. The pilot must review the MEL and deferred items before each flight to be aware of the maintenance state of the aircraft.

At Aerospace Orbit, owned and operated by ASAP Semiconductor, we can help you find all the maintenance tools and equipment for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at sales@aerospaceorbit.com or call us at 1-509-449-7700.


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Over the course of aviation history, many different types of airplane propellers have been used in piston engine-driven aircraft, as advances in materials and engineering opened up greater and greater possibilities in the aircraft propeller's design and engine performance. In this blog, we will explore some of the different types of propellers used over the years.

The first propellers were fixed-pitch, meaning they could not be adjusted in their mountings on the propeller hub, and were made of wood. They were not carved from a single piece, but built layer by layer with specially prepared wood, with black walnut, sugar maple, yellow birch, and black cherry being the most commonly used. Today however, they have been all but supplanted and are typically only seen on historical examples.

Metal fixed-pitch propellers were first invented in the 1940s. Made from aluminum alloy, they were specially treated to be less prone to warping in extreme heat or cold. Today, almost all propellers, including the types on this list, are made from metal so that the propeller lifespan is increased.

Ground-adjustable propellers can have their pitch (the angle the blades are facing) changed, but only when the propeller is not turning. A clamping mechanism holds the propeller blades in place, and the blade’s angle can be changed by loosening this mechanism. There is no way to change the blade’s pitch mid-flight however, so ground-adjustable propellers are not used in modern aircraft.

Controllable pitch propellers can alter the blade’s pitch during flight, while the propeller is still running. This means that the blade angle can be altered to adapt to changing flight conditions. The number of pitch positions is limited and can be adjusted between minimum and maximum pitch settings.

Constant speed propellers accelerate when the airplane dives and slow down when the aircraft climbs due to the changing load on the engine. This is accomplished by the propeller governor, which senses the aircraft’s speed and changes the blade angle to maintain a specific RPM regardless of the aircraft’s operational conditions. This lets the pilot keep the engine speed constant, which lets the pilot focus on other flight conditions.

Feathering propellers are used with multi-engine aircraft. If one or more aircraft engine parts fail, these propellers reduce propeller drag to a minimum. Feathering propellers can change the blade angle of a propeller to 90 degrees and are usually feathered when the engine of the aircraft fails to generate the power needed to turn the propeller. By rotating to an angle parallel to the line of flight, drag is greatly reduced on the aircraft, allowing it to function as a glider.

Lastly, reverse-pitch propellers are controllable aircraft propellers whose blade angles may be changed to a negative value in-flight. The purpose of a reversible pitch is to create a negative blade angle to produce thrust in the opposite direction, which is done to reduce airspeed during landings and take pressure off the brakes.



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Aircraft powered by piston and turboprop engines feature propeller blades that pull or push on the air around the aircraft to provide propulsion. As piston engines have become more powerful, they require more and more propeller blades.

To understand why, we need to understand the working principle of a propeller. The purpose of a propeller is to “absorb” the power produced by the engine and transmit that power to the air passing through the propeller, which generates the thrust force that propels the aircraft through the air. Therefore, if the propeller and engine are not properly matched based on the power of the engine, the system is inefficient.         

As engine power increases, the designer has several different options to design an aircraft propeller that can efficiently absorb that power. However, most of these options have severe drawbacks.

  1.  Increasing the blade angle (or pitch) of the propeller blades allows them to impart more energy to the airflow but altering the blade angle damages the aerodynamic efficiency of the blade.
  2. Increasing propeller length lets the propeller blades impart more energy by affecting a larger volume of air but forces the designer to extend the landing gear as well to keep the prop blades from touching the ground. This in turn forces the landing gear to extend, which causes a domino effect of other structural and weight issues.
  3. Increasing the revolutions per minute of the propeller is an option, but at a certain speed the propeller blades begin to reach supersonic speeds, causing sonic booms at their tips which drastically increases drag.
  4. The camber (or curvature) of the blades can be altered to change their airfoil and generate more thrust. However, this alters the aerodynamic efficiency much like changing the blade angle and can also cause structural issues with the blades, negatively affecting the lifespan of a propeller.

Therefore, there are two viable options for increasing a propeller’s output. Either you can increase the blade’s width, or chord, or increase the number of blades on the propeller. Increasing the blade chord is easier, but once again, changing the chord affects the aircraft’s aerodynamic efficiency. Thus, this leaves us with the last option, increasing the number of aircraft propeller blades. By doing so, you increase the solidity of the propeller disk, the space that the propeller rotates in. By increasing the solidity, the propeller can transfer more power to the air, thus increasing thrust.


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Unlike early aircraft— which merely required a rough surface to land—  modern aircraft are required to have a fully functioning braking system to ensure a safe and full stop. The basic function of an aircraft brake part is to slow and stop the plane on the tarmac. Just as you push down the brake in an automatic car to stop it from moving forward at a red light, the brakes on an aircraft also allow a pilot to hold the plane on the tarmac before take-off or during taxi.

Brakes function using a basic principle of creating heat energy by interrupting the kinetic energy of the plane in motion. When a moving part comes into contact with a stationary object, friction is created. The friction often results in heat energy being released. Depending on the size and type of the aircraft, the brake cylinder can consist of multiple brake pads and rotating disks, or a single rotating disk with one stationary caliper.

In a common brake system, the pilot is able to push or activate a hydraulic or mechanical system that, in turn, applies pressure on the brakes. A pilot will have two separate pedals or rudders that control the left and right brake. In light aircraft, a simple brake mechanism is efficient enough to safely stop and land the plane. When the pilot activates the mechanical system, the single disc brake, consisting of one rotating element, is slowed down by a light squeezing on each side in the form of a fixed stationary caliper. While this type of aviation braking system is sufficient with a light aircraft with a light load, it is not suitable for larger commercial or military aircraft.

The type and function of the aircraft should be considered when fitting the brake system. Certain braking systems are more adept at converting kinetic energy into heat energy, but struggle to dissipate the heat. Vice versa, some braking systems struggle to convert energy, but can efficiently disperse off the heat.

The larger the plane, the more friction is needed to ground it. The large amount of heat that is generated in the braking process can be dangerous and therefore problematic for aircraft manufacturers. The braking system of an aircraft could be damaged if the heat is not correctly spread out across the system. Aircrafts employ different types of cooling methods to spread and disperse off the heat generated. Segmented rotor brake systems were developed to overcome the issue of the large amounts of heat generated in the slowing process. The segmented rotor brake system consists of a series of multiple rotating plates that are sandwiched between stationary brake pads. As the brake pads touch the rotating disks, they briefly interrupt the rotation, converting the kinetic energy to heat. The segmented brakes are designed with spaces in between each brake pad and disc to allow the excess heat to escape.


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The propeller of an aircraft is a crucial component that contributes to flight. A propeller provides the thrust needed to maintain a forward direction. It maintains a rotary motion in which it creates a difference in air pressure between the front and back surfaces of its blades. The shape of the blade contributes to the pressure difference and air displacement. The rotary motion allows the blades to do their job. Most propellers require an engines assistance to spin.

There are several things to consider when operating an aircraft with a propeller. First off is the angle of attack. This is the angle a wing is positioned in oncoming airflow. The pitch angle is also something to consider. This refers to the angle a propeller blade produces with its rotational plane. A controllable-pitch propeller allows the pilot to manually alter the pitch of the blades during flight, enabling it to have peak performance. The design of the propeller can seriously impact the aircraft engine's performance. A combination of the proper angle of attack and pitch angle results in an exceptionally smooth flight.

Prolonging the longevity of your aircraft propeller can be achieved with proper maintenance, preflight inspections, and routine servicing. If a pilot is able to notice an issue early on, they can circumvent a hefty repair bill later. One tip is to clean the aircraft propeller post flight to ensure that any buildup will not cause corrosion, which can lead to damage. Also, apply oil daily if it is stationed in a salty coastal environment. Internal corrosion is a leading cause of major malfunctions in propellers.

Every single propeller has a recommended overhaul interval based on total flight hours and calendar time that has surpassed. Service is needed after approximately 2,000 flight hours or every 5 years for aircrafts that don’t fly regularly. If your engine needs repair before your propeller does, it can be advantageous to replace both at the same time.

Regular balance checks on your propeller can also help increase the life of your aircraft engine, save costs in repairs, and improve the overall performance of the aircraft. Anytime you replace or remove your propeller you should have it dynamically balanced. Another sign that a balance is needed is if your plane vibrates excessively. Keep in mind that having your propeller balanced will not help disguise other engine issues.

Replacing your propeller with a new one results in improved takeoff and climb, quieter flights, a gain in ground clearance, and a much more satisfactory experience.


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The propeller system is the earliest thrust generator designed for fully powered aircraft flight. Though they have evolved quite a bit since their first operation by the Wright brothers in 1903, propellers utilize essentially the same principles of motion. Let’s take a look at how they work.

At its most fundamental level, an aircraft propeller blade needs to generate thrust to create upward and forward motion. As a whole, it is a device with twisted blades that are pointed at an angle and extend from a hub that is rotated via the power of an engine or motor.  A propeller blade has the capacity to create lift by altering the direction of air that comes into contact with it. This process is representative of Newton’s third law of motion or law of action and reaction. The force of air flow applied to a propeller blade has the potential to create levels of both drag and lift. Lift, by definition, acts perpendicular to the motion of a fluid. Drag applies force in the same direction as fluid movement.

Manipulation of airflow depends on the conservation of momentum, mass, and energy within the propeller system. Air moves as a fluid— it has the ability to redistribute its mass freely while conserving momentum and energy. When airflow interacts with a propeller blade, any change in velocity in one direction can cause a change in velocity in a perpendicular direction.

Propeller blades need to create uniform lift across their length. However, a propeller blade rotates at a lower speed near its hub, and at a higher speed at its tips. This means that the blade tips are traveling a greater distance in the same amount of time as the blade root. The blade must, therefore, account for the difference in speed by incorporating different angles of attack. Propeller blades are designed with a “twist”— they integrate a low angle near their fast-moving tip, and a high angle of attack at the root, ensuring that lift occurs evenly regardless of RPM. The design of the propeller blades have a significant impact on the performance of the aircraft engine. Pitch helps adjust the angle of attack along the propeller blade. It is steeper where a blade is moving more slowly (near the hub) and shallow where a blade is moving faster (tip), allowing for differing angles of attack along the length of the blade.

In order to accelerate air downward to create lift, each propeller blade is shaped like an airfoil. Aerofoil stall, or loss of lift, is prevented by the shape of the blade itself. A propeller blade is usually cambered, just like an airfoil wing. Camber, in this instance, refers to the characteristics of the curve of an airfoil's upper and lower surfaces around the blade and the difference in pressure between the two. A pilot, or engineer, can increase the lifespan of a propeller by regular maintainence.


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 "If I told you half the things I've heard about this Jabba the Hutt, you'd probably short circuit." Since you’re here, these words said to R2D2 in the film Return of the Jedi are probably not the first time you’ve heard of a short circuit. A short circuit is one of the many issues electronic and electrical protection devices are designed to prevent. 

Let’s talk basics. A protection device simply has two main functions: consistency in regulation, and protection of electrical and electronic circuits. At their most basic, circuit protection devices redirect a power supply into a separate circuit, using overcurrent protection. This allows the device to prevent damage to an existing circuit from excessive voltages and currents. Protection devices also may serve as a safeguard to remove the risk of fire hazard and electrocution. Now that we’re caught up on what exactly a protection device is, let’s cover the most common designs that you might come across and when you might encounter them.

1. Circuit Breaker

  • What is it?
    • Electrical switch
    • Stops a current when there is excess voltage, or when a system failure occurs
  • When is it used?
  • Utilized to protect against an electrical short circuit
    • Useful on both high current and low current circuits 

2.Fuse

  • What is it?
    • Electronic device
    • Metal strip that has the capability to liquify when current flow is too high
    • Categorized by intended application, response time, and breaking
    • When is it used?
    • In systems where protection is needed without a large disruption

3.  Poly Switch (Multifuse/Polyfuse)

  • What is it?
    • Passive electrical device
    • Protects from over current errors
    • Operates as a resettable fuse
  • When is it used?
    • Commonly used on mechanical transforms, computer power supplies, and nuclear or aerospace applications

4.   Residual Current Circuit Breaker (RCCB/RCD)

  • What is it?
    • Electronic device
    • Testable & resettable
    • Shut-off capability - will identify an issue in power supply, and shut off within a short period
    • Does not protect against overload of a circuit
  • When is it used?
    • Home power supply

5.   Surge Protection Device

  • What is it?
    • Electrical device
    • Most common protection unit for over-voltage protection
    • Well organized mechanism
    • Can be used in most stages of a system
  • When is it used?
    • Electrical fitting security systems

6. Metal Oxide Variable Resistor/Voltage Dependent Resistor (VDR)

  • What is it?
    • Electronic device
    • Resistance varies based on incoming voltage
  • When is it used?
    • Applicable with electrical circuits that are vulnerable to electrostatic discharge and/or lighting

7. Gas Discharge Tube/Expulsion Lamps

  • What is it?
    • Electrical device
    • Gas filled tube - electrodes are contained within the gas, and held in an insulated, temperature resistant capsule
    • Able to ionize gas using incoming voltage

  • When is it used?
    • Switching device for electrical protection
    • Lightning protection

8. Inrush Current Limiter

  • What is it?
    • Electrical device
    • Stops inrush current before it reaches circuit breakers and fuses to reduce potential damage
    • High resistance capability
    • Heat protection allows flow of current on a regular basis
    • When is it used?
    • Fixed resistors
    • NTC Thermistors


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Heat exchangers are used to transfer heat from one source to another. Thermal energy is transferred from one source to another without water and gas coming into contact with each other. These heat exchangers are commonly used in a variety of aircraft components. In aviation, flat tube and plate-fin heat exchangers are the most commonly used in aviation. These components must be properly cleaned in order to function smoothly.

Because they will be used at high altitudes, temperature, air density, and pressure resistance all need to be taken into consideration. The fan component used in the heat exchanger must also be carefully selected since more airflow is required to remove heat in higher altitudes where air density is much lower.

Liquid cooling tends to perform better than air cooling alone. Liquid cooling is also quieter and less vulnerable to the problems associated with high altitudes. It requires less power and weighs less because there is no need for a large fan or wide spacing.

Plate-fin heat exchangers use plates and finned chambers in order to transfer heat. They can be used for air-to-air, air-to-liquid, or liquid-to-liquid cooling. Considering their weight, this type of heat exchanger part performs very well.

Flat tube heat sink parts consist of several flat tubes that are vacuum-brazed in between. These tend to be less expensive than plate-fin designs.

There are high standards when it comes to cleaning heat exchangers. This is due to all the strict and stringent safety requirements that govern aviation. The amount of buildup can be estimated based on past experiences as well as the number of hours flown.


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