Module 7c : Maintenance Practices Avionics

A Pitot-Static Test Set is used for testing altitude and airspeed indications. This device is specifically designed to measure and calibrate the Pitot and Static systems of an aircraft. The Pitot system measures the dynamic pressure of the airspeed, while the Static system measures the static pressure for altitude indication. By using a Pitot-Static Test Set, technicians can ensure that the aircraft's altitude and airspeed instruments are accurately calibrated and functioning properly.

If a bundle passes through a bulkhead hole and the clearance is less than 1/4 inch, it is necessary to have a protective rubber grommet. This grommet acts as a barrier between the bundle and the sharp edges of the hole, preventing any damage or abrasion to the wires. It also helps to provide a secure and tight fit, ensuring that the bundle is properly protected and secured in place. Having more wires to fill the hole or more adequate spacing for clearance may not be sufficient in preventing potential damage, making the protective rubber grommet the correct choice.

The purpose of the knob is to adjust the needle for calibration. This suggests that the knob is used to align the needle with the correct measurement or reference point, ensuring the accuracy of the meter. By adjusting the needle, the user can calibrate the meter to provide precise readings.

Flux is the correct answer because it is a substance that is applied to the surface of a work piece before soldering to remove any oxide layers. Oxide layers can prevent proper bonding and adhesion between the solder and the work piece, so flux helps to clean the surface and improve the soldering process. Solder and tin are not used for removing oxide layers, they are actually the materials used for joining or bonding the work pieces together.

Aircraft bonding refers to the process of grounding all aircraft components to the structure. This is done to ensure that there is a continuous electrical path to dissipate any static electricity or electrical charges that may build up during flight. By bonding the components, any potential difference between them is eliminated, reducing the risk of electrical arcing or sparking. This helps to prevent damage to the aircraft and ensures the safety of the passengers and crew on board.

A heatsink is used to dissipate heat generated by electronic components such as processors, transistors, or graphics cards. It helps to transfer the heat away from the component and into the surrounding environment, preventing overheating and potential damage to the device. By increasing the surface area available for heat transfer, a heatsink allows for more efficient cooling and helps to maintain optimal operating temperatures.

Safety Ohmmeters are specifically designed for ultra-safe resistance measurements on explosive devices and in hazardous environments. These devices are built with robust safety features to ensure that they can be used in potentially dangerous situations without causing any harm. They are often used in industries such as mining, oil and gas, and chemical plants, where there is a high risk of explosions or other hazardous conditions. Safety Ohmmeters are essential tools for maintaining safety standards and preventing accidents in these environments.

All answers are correct.

ATC Transponder Test Set and DME Tester are both correct.

A Megger is a device that is specifically designed to measure the resistance of insulation while subjecting it to a high voltage. It is commonly used in electrical testing and maintenance to ensure the integrity of insulation in various electrical systems and equipment. The device applies a high voltage to the insulation and measures the resulting current flow, allowing technicians to assess the quality and effectiveness of the insulation. Therefore, the Megger is the correct device for measuring insulation resistance under high voltage conditions.

A signal generator is a device used to produce electrical signals of desired frequencies and amplitudes. It is commonly used in various applications such as testing and troubleshooting electronic circuits, calibrating equipment, and generating signals for research purposes. Unlike an oscilloscope, which is used to visualize and measure electrical waveforms, a signal generator is specifically designed to generate electrical signals. A time domain reflectometer, on the other hand, is used for measuring the length and impedance of transmission lines. Therefore, the correct answer is Signal Generator.

The crimp types for 22-18 AWG size are identified with the color code red. This means that when working with wires of this size, crimps or connectors with a red color code should be used. The color coding system helps to ensure that the correct crimp type is selected for the specific wire size, allowing for a secure and reliable connection.

Solder is the correct answer because it is the filler material that is used to create a physical and electrical bond between metals. When heated, solder melts and forms a joint between the metals, providing a strong and reliable connection. Flux and resin are not the correct answers as they are materials that are used in conjunction with solder to clean and prepare the surfaces of the metals before soldering.

An oscilloscope is a device used to determine the shape of a video pulse or signal appearing at a selected test point. It is a tool that displays voltage signals as a two-dimensional graph, allowing users to analyze and measure various electrical waveforms. Oscilloscopes are commonly used in electronics, telecommunications, and engineering fields to troubleshoot and diagnose problems in circuits and signals. They provide visual representations of waveforms, helping technicians and engineers understand the characteristics of the signal and identify any abnormalities or distortions.

The Fuel Quantity Indication Tester works based on the principle of capacitance. Capacitance is the ability of a system to store an electric charge. In this case, the tester measures the capacitance of the fuel quantity indication system to determine the amount of fuel present. This is done by measuring the change in capacitance as the fuel level changes. By using capacitance, the tester can accurately indicate the quantity of fuel in the tank.

A safety ohmmeter is used to check the resistance of a fire extinguisher squib in an aircraft fire extinguishing system. This type of equipment is specifically designed to measure electrical resistance in a safe and controlled manner. It ensures that the squib is functioning properly and has the correct resistance within the system. This is important for the overall safety and effectiveness of the fire extinguishing system in an aircraft.

The diagram suggests the use of the surface wire method for track repair. This method involves placing wires directly on the surface of the track to bridge any gaps or breaks, ensuring continuity and allowing for the smooth flow of electricity. Unlike the through board wire method, which involves running wires through the circuit board, and the foil jumper method, which uses thin strips of foil to connect components, the surface wire method is specifically designed for repairing track issues.

A magnetic temperature controlled soldering iron uses the magnetic properties of the soldering tip to regulate its temperature. This type of soldering iron has a temperature sensor embedded in the tip that detects changes in magnetic properties as the temperature changes. The sensor then sends a signal to the temperature control unit, which adjusts the power supplied to the tip to maintain a constant temperature. This ensures precise and consistent temperature control during soldering operations.

An attenuator is a device used to reduce the amplitude of a signal without distorting its waveform. It is commonly used in audio and telecommunications systems to control signal levels and prevent overloading of downstream components. Unlike an amplifier, which increases the signal strength, an attenuator decreases the signal power while maintaining the shape and characteristics of the original waveform. This allows for precise control and adjustment of signal levels without introducing any distortion or unwanted artifacts. Therefore, an attenuator is the correct device for attenuating a signal without distorting the waveform.

A signal generator used for testing LOC, G/S, VOR, MKR, and communication systems is called a Nav-Comm Ramp Tester. This device is specifically designed to test and simulate signals for navigation (LOC, G/S, VOR) and communication systems. It is used to ensure the proper functioning and accuracy of these systems during testing and maintenance procedures. The Nav-Comm Ramp Tester provides a comprehensive solution for testing multiple systems in one device, making it an essential tool for aviation professionals.

Damping is the process of reducing or eliminating the oscillation of the pointer in a d'Arsonval meter. It involves adding a damping mechanism such as a fluid or magnetic system that provides resistance to the movement of the pointer. This resistance helps to slow down the movement of the pointer, preventing it from oscillating rapidly and allowing for more accurate readings.

To measure voltage in a circuit, the voltmeter should be connected in parallel. This is because connecting the voltmeter in parallel allows it to measure the potential difference across a specific component or set of components in the circuit. If the voltmeter were connected in series, it would disrupt the circuit and affect the voltage being measured. Therefore, connecting the voltmeter in parallel ensures accurate measurements of voltage without interfering with the circuit's operation.

The purpose of the mirror on the scale of an analogue meter is to remove parallax error. Parallax error occurs when the observer's line of sight is not directly perpendicular to the scale, causing the pointer to appear at a different position than it actually is. By using a mirror, the observer can align their line of sight with the reflection of the pointer, eliminating parallax error and allowing for more accurate readings.

When securing wire bundles, it is important that they are able to be deflected about 0.5 inches with normal pressure applied between any two supports. This means that the wire bundles should have some flexibility and be able to move slightly without breaking or becoming damaged. This allows for any expansion, contraction, or movement of the wire bundles without causing stress or strain on the wires themselves.

An RF Directional Wattmeter is used to measure both forward and reflected power of RF radio devices. This device is designed to measure the power flow in a specific direction, allowing users to accurately measure the power being transmitted by the device as well as any power that is being reflected back. It is commonly used in RF and microwave systems to ensure the efficiency and performance of the radio devices. The other options, Time Domain Reflectometer and ATC/DME Meter, are not specifically designed for measuring forward and reflected power in RF radio devices.

The pointer in a permanent magnet moving coil is returned to its original position by the use of a hairspring. A hairspring is a thin, coiled strip of metal that provides a restoring force to bring the pointer back to its starting position after it has been deflected. This ensures that the pointer always returns to zero when there is no current flowing through the coil.

The correct answer is "Butt splice". A butt splice is a type of electrical connection where two wires are joined end-to-end by aligning the ends and securing them together. This type of splice is commonly used when extending or repairing wires, as it provides a secure and reliable connection. It is made by stripping the insulation from the wire ends, overlapping them, and then soldering or crimping them together. The resulting connection is strong and maintains the electrical continuity between the wires.

Tinning is the process of coating a wire with a thin layer of solder. This is done to ensure solderability, which means that the wire can easily form a strong bond with other soldered components. Tinning also helps to keep all strands of the wire together, preventing them from fraying or separating. By applying solder to the wire, it forms a protective layer that prevents oxidation and corrosion, ensuring the wire remains in good condition and maintains its conductivity.

A solder sleeve is used to attach a ground wire to the shielding braid of coaxial cable. The solder sleeve is a heat-shrinkable tube that contains solder inside. When heat is applied, the solder melts and creates a secure connection between the ground wire and the shielding braid. This ensures proper grounding of the coaxial cable, which helps to reduce interference and improve signal quality.

When testing for insulation resistance, it is necessary to test at a voltage approximately 1.5 times the operating voltage. This is because testing at a higher voltage helps to ensure that the insulation can withstand the normal operating voltage without any breakdown or failure. By testing at a higher voltage, any potential weak points or defects in the insulation can be identified and addressed before they cause any issues during normal operation. Therefore, testing at 1.5 times the operating voltage provides a margin of safety and helps to ensure the reliability and performance of the insulation.

An ammeter must never be connected in parallel with the power supply because it will result in a short circuit. Connecting the ammeter in parallel would create a low-resistance path for the current to bypass the intended circuit, causing an excessive current flow that could damage the ammeter and potentially other components in the circuit. Therefore, it is important to always connect the ammeter in series with the circuit to accurately measure the current flowing through it.

The explanation for the correct answer is that the white side is used for the removal of contacts. This implies that the red side is not used for contact removal, and both sides cannot be used for removal.

The correct answer is "Permanent magnet moving-coil movement." This type of meter movement uses a permanent magnet to create a magnetic field, which interacts with a coil of wire that moves when current flows through it. The movement of the coil is proportional to the current being measured, allowing the meter to display the current value. This type of meter is commonly used in ammeters and voltmeters.

A logic probe is a device used to determine the digital state of an electronic circuit. It is commonly used by technicians and engineers to troubleshoot and test digital circuits. The logic probe detects and indicates whether a voltage level is high (logic 1) or low (logic 0) in the circuit being tested. It is a simple and convenient tool for checking the logic levels and diagnosing problems in digital circuits.

The question asks for the equivalent RMS voltage when the voltage at the selected test point is measured as 100V using an oscilloscope. The RMS voltage is the root mean square value of the voltage, which represents the effective voltage. Since the question does not provide any additional information or context, it can be assumed that the equivalent RMS voltage is the same as the measured voltage, which is 100V. Therefore, the correct answer is 70V.

Dry joints are soldering defects that are caused by poor wetting. Poor wetting occurs when the solder does not fully flow and adhere to the surfaces being joined, resulting in an incomplete bond. This can be caused by factors such as dirty or oxidized surfaces, incorrect soldering temperature, or insufficient flux. Dry joints can lead to poor electrical conductivity, weak mechanical strength, and potential failure of the soldered joint.

A current transformer is a device that is categorized by ratios such as 50:5, 100:5, 300:5, etc. These ratios represent the relationship between the current flowing through the conductor and the current measured by the meter. Current transformers are commonly used in electrical systems to step down high currents to a level that can be safely measured by ammeters or other measuring devices. They are designed to provide accurate and proportional current measurements, making them an essential component in various applications, including power distribution systems and electrical equipment monitoring.

If the voltmeter is reverse connected into an energized circuit, the needle might be damaged. When the voltmeter is connected in reverse, it will measure the voltage in the opposite direction. This can cause the needle to move beyond its maximum range, potentially causing damage to the needle or the internal components of the voltmeter.

The purpose of a sacrificial washer installed with the bonding strap is to protect the connection from corrosion. Corrosion can occur due to various factors such as moisture, chemicals, and environmental conditions. The sacrificial washer acts as a barrier between the bonding strap and the connection, preventing direct contact and reducing the risk of corrosion. By sacrificing itself, the washer corrodes instead of the connection, prolonging the lifespan and integrity of the connection.

The problem in the crimped ring terminal is that the conductors are not properly crimped. This means that the conductors are not securely attached to the terminal, which can lead to a poor electrical connection and potential failure. Crimping is a process of compressing the metal terminal around the wire, creating a strong and reliable connection. If the conductors are not crimped, it is likely that they are loose or can easily detach from the terminal, causing issues with the electrical circuit.

A small quantity of solder applied to the junction of the working surfaces and the soldering tip is called a heatbridge. A heatbridge helps in transferring heat efficiently between the soldering tip and the components being soldered, ensuring proper soldering and preventing damage to the components. It acts as a bridge for heat to flow and helps in maintaining a consistent temperature during the soldering process. Heatbridges are commonly used in electronics soldering to ensure reliable connections and prevent overheating.

A RF Directional Wattmeter measures the power flowing in the forward direction. When the arrow is toward the load, it indicates that the power is flowing from the source to the load. Therefore, the RF Directional Wattmeter is measuring the Forward Power.

The gauge size of wire typically determines the thickness of the wire. A larger gauge number indicates a thinner wire. Since 10 AWG is a larger gauge size compared to 20 AWG and 16 AWG, it suggests that 10 AWG wire is thicker. Thicker wires are often used for higher current applications, and in such cases, uninsulated terminals are commonly used to connect the wire securely. Therefore, 10 AWG wire typically uses an uninsulated terminal.

Using cable ties or tie wraps is not allowed when installing a coaxial cable. This is because cable ties or tie wraps can exert too much pressure on the cable, which can lead to signal loss or damage. It is recommended to use other methods such as clips or clamps to secure the coaxial cable instead.

An ohmmeter with a sensitivity of 10,000 per volt means that for every volt applied, the ohmmeter will read 10,000 ohms. Therefore, if 1 milliamp of current is applied at full scale deflection (FSD), the ohmmeter will read 10,000 ohms. So, 1000 ohms resistance is needed to produce 1 milliamp of current at FSD.

A knife splice is a temporary splice type used to join two wires together. It involves stripping the insulation from the ends of the wires, overlapping them, and then wrapping them tightly with electrical tape. This type of splice is typically used when a permanent connection is not required, such as during testing or troubleshooting. It can easily be undone by removing the tape and separating the wires, making it a temporary solution. Butt splice and ring terminal, on the other hand, are permanent splice types used for secure and long-lasting connections.

A voltmeter is used to measure the voltage, or potential difference, across a circuit. In this context, the pressure being applied to the circuit refers to the voltage. Therefore, a voltmeter is the appropriate meter to measure the pressure being applied to the circuit.

Wire wrapping is a type of solderless termination shown in the given question. This technique involves tightly wrapping a wire around a post or terminal to create a secure and reliable connection. It is commonly used in electronics and telecommunications industries for making connections on circuit boards or creating custom wiring harnesses. Wire wrapping provides a strong mechanical connection and is preferred when soldering is not feasible or desirable.

A solder wick is a tool used to remove solder from a base material. It consists of a braided copper wire that absorbs the molten solder when heated with a soldering iron. The wick acts like a sponge, drawing the solder away from the joint and onto the wick. This is a common method used in electronics to desolder components or repair circuit boards. The desoldering pump and solder pot are not used for removing solder from a base material, making them incorrect options.

All answers are correct.