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1 - Digital Calipers1 - Socket
Fill in your chosen socket size here: . 
What is the listed accuracy of the calipers? What is the listed resolution of the calipers? What is the difference between accuracy and resolution?
What are two potential sources of systematic/random error?
1 - Digital Multimeter1 - Believer DA-15 Cable
Modern DMMs protect themselves from overcurrent. What electrical safety device provides this protection? The DMM has three ports/plugs on the bottom. Complete the table below, explaining what each port is for.
In aviation applications, why are crimps preferred over soldering?
Why is it important to always return a torque wrench to zero?
Why is it important to use a torque wrench instead of just “tightening until it feels snug”?
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Maintenance Tools - Sept. 18th, 2025
Overview
This lab introduces students to a set of essential measurement and assembly tools used in aviation maintenance: digital calipers, digital multimeters, crimping tools, and torque wrenches. Through hands-on exercises, you will learn how to measure dimensions with precision, test electrical continuity, create reliable wire connections, and properly torque fasteners. Each activity emphasizes accuracy, safety, and good technique, helping you build a foundation in tool use that is critical for quality control, system reliability, and professional practice.
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Assignment
Caliper
Figure 1: Digital Caliper
Introduction to Using Calipers
Digital Calipers are precision instruments that measure internal, external, and depth dimensions. They provide quick, accurate digital readouts, making them essential for ensuring proper fit, design accuracy, and quality control. This lab will cover how to read measurements and tips for practical use.
Equipment
Collect the following equipment
Making Measurements
In this section, you will measure the outer diameter, inner diameter, and depth of a socket.
Measurements Table 2
Item
Item Dimension
Measurement (in)
Measurement (mm)
Image
Notes
3
Outer Diameter
0.68
17.4
Open
Inner Diameter
0.51
13.1
Open
Depth
1.33
33.7
Open
Questions
Answer the following questions about calipers. Use any resource (AI, Wikipedia, etc.).
[ ]
[ ]
Digital Multimeter (DMM)
Figure 2: Digital Multimeter
Introduction to Multimeters
Digital Multimeters (AstroAI AM33D) are handheld instruments used to measure voltage, current, resistance, and check continuity or diodes. They provide a digital readout and require the user to select the correct range before measuring, making them reliable tools for basic electrical testing.
Equipment
Collect the following equipment
DMM Settings
In this section, you will learn about the different measurement settings available on a DMM, what it measures, and the range and limits.
Setting Name
What it Measures
Range/Limit
Image
AC Voltage Test
AC Voltage (V)
AC Voltage 500V Limit
DC Current Test
DC Current (μA)
DC Current 2000μA Limit
DC Current Test
DC Current (mV)
DC Current 200mV Limit
Continuity / Diode Test
Resistance tests for complete connection (No broken wires) and ensures the diodes are passing current through the right direction. (Ω)
Operating limit is typically under 50Ω
Resistance
Resistance throughout the circuit and voltage drops. (M)
Resistance 200M Limit
DC Voltage Test
DC Voltage (mV)
DC Voltage 2000mV Limit
DC Voltage Test
DC Voltage (V)
DC Voltage 200V Limit
There are no rows in this table
Making Measurements
Now it’s time to put the DMM to use by using the continuity settings to learn the pinout of a DA-15 connector. D-subminiature or D-sub connectors are commonly used connectors in the digital signal world, and we will be working with the same connector used in the Believer wing section. Follow the steps below:
1 = Black
2 = Red
3 = White
DA-15 Pinout Table 2
DA-15
Connector Name
Pin Number
1
Power +
N/A
2
Power +
N/A
3
AIL & RUD & ELV
2 & 2 & 2
4
AIL
1
5
RUD
1
6
ELV
1
7
Power -
N/A
8
Power -
N/A
9
Power +
N/A
10
Power +
N/A
11
AIL
3
12
RUD
3
13
ELV
3
14
Power -
N/A
15
Power -
N/A
There are no rows in this table
Questions
Answer the following questions about DMMs. Use any resource (AI, Wikipedia, etc.).
DMM Ports 2
Port Name
Port Purpose
COM
Open
VΩmA⎍
Open
10A_MAX_
Open
There are no rows in this table
Crimping
Figure 4: Wire crimper
Introduction to Crimping
Crimp Tools are used to join wires to connectors by compressing (or “crimping”) a metal sleeve around the wire. This creates a secure mechanical and electrical connection without the need for soldering.
Making Crimps
Follow the steps below to remanufacture a servo cable.
Crimp Analysis Table 2
Wire Gauge
Connector Type
Crimp Tool Slot Setting
Image of Crimp
Inspection
Reflection of Crimp
3
3
3
Open
Open
Open
Questions
[ ]
Torquing
Torque Wrenches are precision tools used to apply a specific amount of torque to a fastener, such as a bolt or nut. They ensure that parts are tightened enough to hold securely without being over-tightened, which can damage components.
Table Assembly
In this section, we will assemble a lab table. Follow the steps below.
Torque Table 2
Bolt Head Size
Specified Torque Value (LB IN)
Student Torque Setting
Instructor Sign-off
3
40
64
111
Questions
[ ]
[ ]
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