5-3) Reading Aircraft Diagrams Flashcards
What are the 7 types of diagrams/schematics used in aviation?
- Block Diagrams
- Flow Charts
- Logic Diagrams
- Diagram Schematics
- Electrical Schematics
- Illustrated Parts Catalog
- Air Transport Wiring Diagrams
What type of diagram/schematic is in the image sample and how is it used?
Block Diagram
Uses blocks connected by lines to show relationships to other blocks in the drawing. Up to the reader to determine the function of each block. Shows communication path between the blocks and gives the reader a quick visual of what is not communicating with each other by using one-way or two-way arrows to show signal flow.
What type of diagram/schematic is in the image sample and how is it used?
Flow Chart
Flow charts are used where a set path is following to its conclusion with intermediate decision steps along the way. Flow charts can be equally useful for troubleshooting an aircraft system, or even receiving a part into a repair facility.
Parts of a flow chart are very basic; they contain start and stop bubbles, information boxes, and decision blocks.
Actions required are determined by the shape of the flow symbol. In aviation, flow charts are used in system troubleshooting to help technicians find problems in complex aircraft systems.
Describe the function of this flow chart block.
Oval shape is to show a start or stop point. This ensures that a step or process is not missed.
Describe the function of this flow chart block.
This block instructs the reader to add something to the flow. This could be entering test parameters for an avionics tester or computer.
Describe the function of this flow chart block.
This is where the reader is expected to perform a task before going to the next block. This could be: open a document, a form, or prepare an aircraft for a test.
Describe the function of this flow chart block.
This block could contains a maintenance manual reference or another document to help the reader in the flow process. This could describe a document where the various instructions for each step are contained.
Describe the function of this flow chart block.
The decision block is where the reader is directed to go to some other path based on an outcome. For example, a previous step could have a process block that tells the technician to perform a function test. For a decision block to work, the outcome must be definitive.
The outcome could be pass/fail, left/right or yes/no. The diamond shape is for a line in from the previous step and then one or two lines out. Although some flow charts have 3 lines out, that would often complicate the situation.
Almost all flow charts deal in pass or fail decisions.
Describe the function of this flow chart block.
Logic Diagram
Similar to flow charts, they have inputs and a final output. Instead of “pass/fail,” the output of a logic diagram is “High/Low,” “On/Off,” or “1/0.” The output is dependent on the symbol inserted into the chart.
Some flow charts will incorporate logic symbols as a decision symbol where a yes or no is not enough. Logic gates can also have more than two inputs for a single output.
Describe the function of this flow chart block.
Schematic Diagram
Pictorial type of drawing that uses the simplest means possible to explain an object or system. It shows the basic recognizable shape of each component (even if this don’t actually look like that) and it shows the wiring of which component connects to which other components.
This type of diagram would not have enough detail to troubleshoot the system. This type of drawing is used in Pilots Operating Handbooks for small, simple general aviation aircraft.
Describe the function of this flow chart block.
System Schematics
There are many types of system schematics–hydraulic, pneumatic, or fuel.
System schematics will have some legend to describe the various fluids and different pressures. Each schematic would show where fluid or gasses can be ported. They show valves and actuators to explain an operation or action. They also include an index to show the different materials that flow through the sytems.
Describe the function of this flow chart block.
Electrical Schematics
Two types of electrical schematics: one showing individual electronic components in a single circuit (oscillator). The second showing a much more complex system that contains many components. Instead of showing the individual components, this is a block diagram with individual wires illustrating which subsystems connect to which others.
Describe the function of this flow chart block.
Illustrated Parts Catalog
Helps technician locate parts that cross reference a part number and other identifying codes. Type of drawing gives the technician a picture of components broken down into individual parts. Part numbers correspond to a parts list manual on the drawing page.
Describe the function of this flow chart block.
Air Transport Wiring Diagram
Some wires in GA aircraft may only have various colors to ID wires. Typical GA aircraft have none of the wires marked because GA systems are relatively simple and the technician need not have a much more detailed diagram to troubleshoot the system.
Air Transport aircraft may have thousands of wires, so every Wiring Diagram Manual has an index that will describe in detail the processes used to create the schematic, how the wires and labeled, colored and marked.
Describe how to read this autopilot system block diagram.
- Shows a wire bundle assembly between two disconnects.
- Bundle W141 runs between D4153J in the instrument panel to D347 in the electronics bay.
- Wire number is the label for individual wires or individual groups of wires in a bundled section.
- Wires in the group are colored, not numbered
What are the 4 pieces of information labeled on this wire?
- Bundle Assembly Number
- Wire Number
- Wire Gage
- Wire Grouping
Name each of the steps in general aircraft electrical system (left to right)
Describe the function of this type of diagram/schematic.
Pictorial Diagram
A simple drawing of the components themselves that include a connection between the parts. This type of drawing is used only to show the physical location of system components. It will not show the electrical connections. It also usually shows only the major component but might leave out items such as switches and relays.
Explain what this schematic is showing and how it operates
This is a simple schematic interpretation of a landing gear electromechanical assembly.
There is a two position switch that provides power to two motors. One motor extends the landing gear, the other motor retracts the landing gear. With the switch in either position, we can see which motor is engaged and what the landing gear is doing.
Explain what this schematic is showing and how it operates
This is a simple schematic of a landing light assembly that may be located on the leading edge of the wing or in a nose position.
For slow aircraft, this simple configuration is appropriate to illuminate the area for landing or taxi. Most problems are usually found with the light lamps and a simple multimeter can be used to trace the wires.
What is this piece of equipment and how is it used?
Landing Light Assembly
What piece of equipment is this a schematic of and what are its components?
Self contained retractable landing light assembly. Some lights need to be placed on the aircraft so they are spaced farther apart. The light must be extended on take off and landing but retracting while the aircraft is cruising.
Each landing light assembly is a self-contained unit with a light, gearbox, motor, and contains micro switches that control the travel of the light and the process of extension and retraction.
Explain what this schematic is showing and how it operates
This is a control system for a retractable landing light. Uses a two-position STDP switch that operates both the motor drive and the relay for the lights. There is a copper contract track that will provide electrical power to the light when the switch powers both the relay and the light itself is in any other position other than full retract.
Explain what this schematic is showing and how it operates
This is a split field winding motor which means that it will move in either direction depending on which field coil is being powered. Power for the retract circuit comes from the contacts on the micro-switch (far right of drawing, not shown here). This energizes the left field coil of the motor.
Explain what this schematic is showing and how it operates
This is the solenoid brake on the retractable landing light motor assembly. The purpose of this circuit is to only have power to the solenoid when the light is in motion. At any other time, this magnetic brake holds the light in position. Whenever current is flowing through the motor, the solenoid is activated and the brake is temporarily released.
Why are there 2 micro switches in the retractable landing light assembly?
What does the quarter circle bar attached to the light assembly do?
Micro switches are alternately opened and closed based on the motion of the light assembly.
In the path of motion of the light is a conducting bar that ensures that the motor continues to run the full length of travel for extending and retracting. As soon as the light assembly extends about 10°, the light assembly contacts the bar completing the circuit for the light and the light will switch on while it is in motion on its way to being extended.
What would happen if the microswitches are misaligned at all?
If the switches are not rigged correctly, the light may not retract full or be aimed incorrectly when extended. The switches perform the function of breaking electrical continuity with the motor at the precise moment that the light assembly retracts (retract micro switch) and at the precise moment when the light assembly extends (extend micro switch). If they are not installed exactly correctly the light could fail to open/close or close/open partially.
What role does the relay play in the retractable light assembly?
The relay provides power to the copper bar, which conducts current to illuminate the lamp. The current through the relay contacts is conducted through the bar as soon as the relay contacts close.
The relay coil current is also directed through the Extend Micro Switch, and into the extend half of the field coil motor. This current starts the motor turning to extend the assembly. After 10° of motion, the light will contact the conductive bar and the light will illuminate.
When the light needs to retract from the extended position, how does this work?
After the light reached the extended position the the first place, the motion of the light assembly OPENS the Extend Micro Switch, which broke contact with the with the right side of the split field coil motor.
At the same time, the light assembly CLOSED the Retract Micro Switch, so that current could be provided to the left side of the split field coil motor. Even though the two micro switches have swapped positions, the motor won’t do anything until the control switch has been moved from extend to retract.
One the Retract switch is thrown, current moved from the DC Bus through the switch and into the left side of the split field coil. It also immediately disengages the relay, which cuts power from the conducting bar (light goes off) and current is removed from the Extend Micro Switch.
When the assembly retracts completely, it makes contact with the retract micro switch to open the circuit to the motor, which causes it to stop moving.
How is it that the motor break is only disengaged when the motor is moving?
No matter which side of the split field coil is activated, the path to ground for the motor is THROUGH the break solenoid. This current creates and electromagnetic field through the coil, which pulls the break AWAY from the motor, pushing against the single acting spring. As soon as current stops moving through the motor, the solenoid is disengages and the single acting spring pulls the break back into place to stop any motion in the motor.
