10 Questions
What type of thread fit do aircraft screws typically have for ease of assembly?
Class 2
How should you tighten a right-hand thread?
By turning it clockwise
What tool is typically required to turn a nut onto a bolt for a Class 4 fit?
Wrench
How can the screw thread pitch on a screw, bolt, or tapped hole be verified and measured?
With a screw thread pitch gauge
What is the purpose of a go-no go gauge in relation to threaded plugs and holes?
To check if the plug fits within tolerance limits
How should left-hand threads be tightened?
By turning them counterclockwise
What should be done periodically to ensure thread gauges are accurate?
Check daily
Why should you be careful not to force the gauge into the test hole when using go-no go gauges?
To avoid damaging the thread
What is the recommended frequency for checking thread gauges that are used intermittently?
Weekly
Why is it important to periodically check thread gauges used continuously?
To ensure they are not worn beyond permissible limits or damaged
Study Notes
- Aircraft hardware includes fasteners and miscellaneous items used in aircraft manufacturing and repair.
- Common methods to hold metal parts together include riveting, bolting, brazing, and welding.
- Fasteners are crucial in assembling aircraft parts, designed based on the type of loads they will encounter.
- Various international standards organizations dictate specifications for aircraft fasteners, such as MS, NAS, AN, ISO, AS, SAE, ASTM, ANSI, and BSI.
- Screws and bolts are common fasteners in aviation, with screws having looser thread fit and no need for a nut, while bolts have a plain portion for a nut.
- Screw thread terminology includes major diameter, minor diameter, pitch, flank, lead, and runout, influencing the strength and functionality of the fastener.
- Coarse and fine pitch threads offer different strengths and grip levels, with fine pitch threads being stronger and offering tighter adjustments.
- Different thread profiles exist for screws, with V-form being common, and international thread systems like Unified and Metric being widely used in aircraft construction.
- Choosing the right threaded fastener is crucial, with part numbers, proper installation locations, and thread tolerances being key considerations to prevent catastrophic consequences.
- Thread tolerances are classified into classes of fit, with Class 3 being common for aircraft bolts and Class 2 for aircraft screws.
- Measuring screw threads can be done using pitch gauges, and Go-NoGo gauges are used to ensure proper fit within tolerance limits.
Test your knowledge on the concepts of single and multi start threads, as well as screw thread profiles. Learn about the differences between single and multi start threads, and the various forms of screw threads used in different countries.
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