Materials and processes Flashcards
Which steel alloy is noted for its toughness and is most commonly used for aircraft structure, frame members, engine mounts, landing gear parts and other structural parts?
Chrome molybdenum steel
How is work hardening metal obtained?
By cold working the metal
Which casehardening process is accomplished on steel alloys, after heat treating, to produce a wear resistant surface on engine parts, such as crankshafts?
Nitriding
What portable hardness test is commonly used for testing aluminum alloys, copper, brass or other relatively soft materials?
Bracol tester
What class of thread are aircraft bolts commonly manufactured?
Class 3, medium fit
How may AN standard steel bolts be identified?
By the code markings on the bolt head
What is the grip length of a bolt?
The unthreaded portion of the bolt
What is the difference between a general purpose bolt and a close tolerance bolt?
Close tolerance bolts are machined to more accurate dimensions than general purpose bolts
Where may self-locking nuts not be used
At joints which either the nut or bolt are subject to rotation
How can the recommended torque for a bolt or nut be determined when torque values are not called out in the maintenance procedures?
Use the information contained in the standard torque table such as in the AC 43.13-1B
What do the markings on the heads of solid shank rivets indicate?
The material of which they are made and their strength
What may be accomplished to prevent heat treated aluminum alloy rivets from becoming hard after the quenching process?
Store them in a freezer
What type of cable is commonly used in primary control systems?
Extra flexible 7x19 stainless steel cable
When performing a penetrant inspection, what happens when the penetrant is applied and removed from a part that is cracked?
The penetrant liquid enters the crack and remains there in order to make the crack visible when developer is applied
What is the procedure for performing a dye penetrant inspection?
Clean the surface, apply the penetrant, remove the penetrant with an emulsifier or cleaner, dry the are, apply the developer and interpret the results
What NDT methods could be used for detecting surface cracks in aluminum fittings?
Dye penetrant, x-ray, ultrasonic, eddy current and visual inspection
Which NDT method can be performed without removing the surface coatings such as primer, paint and anodized films?
Eddy current
Name some tools that are commonly used to assist in making visual inspections of welds
A magnifying glass, a flashlight, a mirror and possibly a borescope
What does the magnetic particle inspection process consist of?
The basic process consists of magnetizing a part and the applying ferromagnetic particles to the surface area to be inspected. If a defect is present, the particles will form a pattern on the surface
What are the penetration requirements for a fillet weld?
Should be 25-50% of the thickness of the base metal
What width should welding beads have and what should be the depth of penetration of a butt weld?
Should be 3-5 times the thickness of the base metal and 100% penetration
What type of precision measuring instruments can be used to measure the outside dimensions of aircraft parts?
Outside micrometers and vernier calipers
Why should a micrometer be periodically calibrated?
To assure its accuracy
What is the main difference between thermoplastic and thermosetting resins?
Thermoplastic is softened by heat and thermosetting does not soften with heat
Why is alloy steel that is responsible for heat treatment usually less suitable for welding?
Because of its tendency to become brittle and lose its ductility in the welded area
What are some of the purposes for which thermoplastic and thermosetting resins are commonly used in modern aircraft?
Thermoplastic is used for windows and windshields and thermosetting is used as matrix material in composite structures
Name one material commonly used as the reinforcing component in structural composite laminates
Aramid (Kevlar), fiberglass and graphite or carbon fiber
Name one substance commonly used as the matrix material in structural composite laminates
Polyester resin and epoxy resin
Name one advantage of using prepreg materials over non-prepreg materials in the construction or repair
Prepreg materials have the proper amount of matrix, the reinforcing fibers are completely and evenly permeated with matrix, the matrix has the correct proportions of resin and hardener and they have a lower cost
What are the undesirable characteristics of a cold weld?
Improper penetration with rough and irregular cold laps not feathered into the base metal
