General: Materials & Processes 🔊 Flashcards
What is a suitable non-destructive testing method for detecting surface cracks on aluminum castings and forgings?
Dye penetration, it detects surface cracks with equal success on aluminum, magnesium, brass, copper, and titanium.
List the steps in a dye-penetrant inspection.
- Thoroughly clean the materials surface
- Apply the penetrant for the specified dwell time
- Remove the penetrant with water or emulsifying cleaner
- Dry the part
- Apply the developer
- Inspect the results
What is the procedure for performing a magnetic particle inspection?
Thoroughly clean all grease oil and dirt from the metal part which must be a ferrous material. Magnetize the part then apply the ferromagnetic particles, either liquid or dry powder. If discontinuity is present, the magnetized particles will form a pattern in the approximate shape of the discontinuity.
What are the two types of self-locking nuts?
All metal and fiber lock or elastic stop nuts
What is the general rule for using self-locking nuts?
Do not use them at joints which are subject to rotation
What type of cable is used in primary control systems?
Extra flexible 7x19 cable
How can correct grip length of a bolt be determined?
The grip length, or unthreaded portion of the bolt shank, should be the total thickness of the material being joined
The length of AN standard bolts are measured in what fraction?
8ths of an inch
What does the triangle mean on the head of a steel bolt?
Close tolerance
What numbers are used for close tolerance bolts?
AN-173 through AN-186 for hex head bolts; NAS-80 through NAS-86 for countersunk bolts
What is the difference between a standard bolt and a close tolerance bolt?
A closed tolerance bolt is machined to more precise dimensions and used in high performance applications
What fraction is used to measure solid rivet diameter?
32nds of an inch
Describe a rivnut.
A threaded body that is expanded to the aircraft structure
What is the purpose of a channel nut or nutplate?
Both allow a screw or bolt to be installed without needing to hold a nut with a wrench
What are common materials for cotter pins to be made from?
Low carbon steel or stainless steel
What is the smallest cable that can be used in primary control systems?
⅛ inch diameter
What should be the depth of penetration when making a fillet weld?
25% to 50% of the thickness of the base metal
What precision measuring instruments are used to measure outside dimensions?
Outside micrometers and Vernier calipers
What term describes a metal that is based in iron?
Ferrous alloy
What should be the width of the weld bead and depth of penetration when making a butt weld?
3 to 5 times the thickness of the base metal with 100% penetration
What system is used to identify AN type aircraft bolts?
They have code markings on the bolt heads for identification. Diameter is measured in 16ths of an inch and length in 8ths of an inch.
What is the difference between close tolerance and regular AN bolts?
Close tolerance bolts are used in applications where the joint is subjected to severe vibrations and load reversals.
What are the steps for solution heat treating aluminum alloys?
Must be heated to a predetermined temperature, heat soaked for a specific period, then rapidly quenched to a relatively low temperature.
In what state is aluminum alloy immediately after solution heat treating and quenching?
Comparatively soft state so it must be naturally aged or precipitation hardened.
What is done to prevent certain aluminum alloy rivets (D and DD) from becoming hard after heat treating and quenching?
They are stored in a refrigerator at temperatures lower than 32°f. They will remain soft for several days. (ice box rivets)
What do rivet head markings indicate?
Alloy of the rivet
Why is alloy steel that is responsive to heat treatment usually less suitable for welding?
It has a tendency to become brittle and lose its ductility around the weld
Why should steel be normalized after welding or machining?
To remove internal stress of the metal, reducing the brittleness
What are two methods of case hardening?
Carburizing and nitriding
What are the characteristics of a cold weld?
Improper penetration and cold laps caused by insufficient heat. They appear rough and irregular with edges not feathered into the base metal.
What tools are used to measure the outside diameter of shafts, thickness of sheet metal stock, diameter of drills, and other similar applications?
Outside micrometer or caliper
What should be used to make a visual inspection of a weld?
At least 10x magnifying glass
Name some types of non-destructive testing used on non-ferrous materials.
Eddy current, dye-penetrant, x-ray, coin tap, and visual
What is the most common type of corrosion?
Surface corrosion
What does a ¼-20 bolt mean?
Bolt diameter and thread count
Why should a micrometer be periodically calibrated?
Ensure accuracy
What fraction is used to measure a solid rivet’s length?
16ths of an inch
What are some types of washers used on aircraft?
Spring lock, flat, lock tooth, tab, finished
What is an SDS?
Safety Data Sheet
What class bolts are used on aircraft?
Class 3 bolts
What class threads are used on aircraft?
Class 3 threads
