O&P Flashcards
What are the study materials referenced for aircraft repair?
AMT-STRUC, FAA-8083-31, AC 43.13.1
When making a riveted repair to an aircraft sheet metal structure, which strength should be greater?
The bearing strength of the sheet should be greater
What type of device is a Cleco fastener?
A patented fastener that holds two pieces of sheet metal together until they can be riveted
What is the main function of throatless shears in an aircraft sheet metal shop?
Used to cut mild carbon steel up to 10-gage and stainless steel up to 12-gage, can cut irregular curves
What is the purpose of a sight line when laying out sheet metal in a cornice brake?
Allows the jaws of the brake to be positioned so the bend starts at the bend tangent line
What kind of metal forming is done by a slip roll former?
Simple curves with a large radius
What kind of metal forming is done by bumping?
Compound curves in sheet metal
What must be done to the flanges of an angle for it to be curved?
Stretch for a convex curve and shrink for a concave curve
What is meant by the bend allowance in sheet metal bending?
The amount of metal used in making the bend
What determines the minimum bend radius that can be used with a piece of sheet metal?
The thickness of the material and its hardness
What is meant by setback when bending sheet metal in a cornice brake?
The distance the jaws of the brake must be set back from the mold line to form the bend
Why are lightening holes in a sheet metal wing rib flanged?
To give the rib rigidity
When hand-forming a piece of sheet metal with a concave curve, where should forming start?
Start at the edges and work toward the center
What is meant by a joggle in sheet metal?
A small offset near the edge that allows the sheet to overlap another piece of metal
When drilling stainless steel, should the drill be turned fast or slow?
It should be turned slowly
What is the minimum edge distance allowed when installing rivets in aircraft sheet metal?
Two times the diameter of the rivet
What is the recommended transverse pitch for riveted two-row splice in sheet metal?
Three-fourths of the pitch of the rivets in the rows
Why should aluminum alloy rivets be driven with as few blows as practical?
Excessive hammering will work-harden the rivets
What determines if sheet metal should be dimpled or countersunk when installing flush rivets?
The thickness of the sheet; countersinking only if thicker than rivet head
What type of metal should be hot-dimpled?
7075-T6, 2024-T81 aluminum alloys, and magnesium alloys
What is the purpose of anodizing a piece of aluminum alloy?
Anodizing is a protective oxide film that is deposited on the surface of aluminum alloy by an electrolytic process.
Why is TIG (GTA) welding preferred over oxyacetylene welding?
The heat is concentrated in the weld and does not cause as much distortion as gas welding.
Why must the pressure of the gas in an acetylene cylinder be kept low?
Acetylene gas becomes unstable when it is kept under pressure of more than about 15 psi.
What are the characteristics of an oxidizing flame produced by an oxy-acetylene torch?
An oxidizing flame has a pointed inner cone, and the torch makes a hissing noise.
What does a neutral flame produced by an oxy-acetylene torch look like?
A neutral flame has a rounded inner cone, and there is no feather around the inner cone.
What is a reducing flame?
A reducing flame has a definite feather around the inner cone.
What is meant by tack welding?
Tack welding is the use of small welded spots to hold the material together until the final bead is run.
Why must thick plates of metal be preheated before welding?
Preheating minimizes the stresses that are caused when welding thick metal.
Why is it important to remove all traces of the welding flux after welding aluminum or magnesium?
Welding flux is corrosive and must be removed to keep the metal from corroding.
What is the function of the inert gas used in TIG (GTA) and MIG (GMA) welding?
The inert gas forms a shield to keep oxygen away from the weld puddle.
What is the difference between brazing and welding?
In brazing, the base metal is not melted, while in welding, the base metal is melted.
What is an acceptable acetylene line pressure for welding with an oxyacetylene rig?
About 5 psi.
How much should the bead penetrate the material in a butt weld?
The joint should have 100 percent penetration.
What kind of flame is recommended when gas welding aluminum?
A soft, neutral oxy-hydrogen flame is recommended.
Is a heat-treated steel part normally repairable by welding?
No, welding destroys the heat treatment.
What kind of solder is recommended for soldering electrical wires?
60/40 resin-core solder.
What is meant by a soft flame?
A soft flame is made when the pressures of the gases are low enough that the flame does not make a noise and does not blow the puddle.
