Materials & Processes Flashcards
What kind of inspection is used to detect flaws in ferromagnetic material on or near the surface?
Magnetic Particle Inspection
These flaws form north and south magnetic poles when the part is magnetized. Iron oxide suspended in a fluid pumped over the part is attracted to and held by the magnetism and it outlines the flaw.
What kind of Inspection method is used to detect faults on both ferrous and nonferrous metals and non porous plastics?
Liquid penetrant
Ultrasonic Inspection uses what to detect faults in a material ?
High-Frequency sound waves.
It can be used on a high variety of materials such as ferrous and nonferrous metals, plastics and ceramics. It can detect subsurface as well as surface defects.
A dent of more then 20% of the tube diameter is not acceptable-True or False?
True, a tube with a dent of more then 20% of the tube diameter must be replaced.
A nick or scratch less than 10% of the wall thickness of the tube is repairable if it is not in the heel of the bend, as are dents that are 10% of tube diameter. True or False
True.
What inspection is used to detect flaws or defects on and below the surface and requires little to no part preparation .
Eddy Current Inspection.
How does Eddy current inspection work?
It induces a magnetic field into the part which causes eddy currents to flow. Variations in the magnitude of the eddy currents affect this magnetic field, and when it is analyzed electronically, it gives information regarding such structural characteristics as flaws, discontinuities, thickness, and alloy or heat-treated condition of the material. Eddy current inspection is used to locate defects both on the surface and below the surface.
Residual method in magnetic particle inspection is the most used method for aircraft parts because it provides the strongest magnetic field. True or False?
False, continuous method is the most used for aircraft parts because of its strong magnetic field.
How is the continuous method of magnetic particle inspection performed?
the part is either placed between the heads of the magnetizing machine or held inside the solenoid (coil). Magnetizing current flows while the fluid is pumped over the part.
How is the residual method of magnetic particle inspection performed?
The parts are magnetized and the magnetizing current is shut off. Only residual magnetism is left in the part to attract the oxide.
What are the many factors of radiographic exposure?
Material thickness and density
Shape and size of the object
Type of defect to be detected
Characteristics of X-ray machine used.
Exposure distance
Exposure angle
Film characteristics
Type of intensifying screen, if used.
The testing medium that is generally used in magnetic testing is what?
finely ground iron oxide with high permeability and low retentivity, that is nontoxic and usually suspended in a light oil such as kerosene
Steel that has a high retentivity or has been heat treated for stressed application, the inductance method is best. True or False
False, Residual Method
What does it mean for a metal to have high retentivity?
It retains its magnetism after the magnetizing force has been removed.
Steel and heat-treated steel have high retentivity and can be inspected with the residual magnetizing inspection method.
When doing a metallic ring test on a bonded honeycomb repair, which is best to use? A coin or a ringing ball peen hammer?
The coin dum dum.
You are so moronic if you thought it was a ringing ball peen hammer. You should just quit school now because there is no way you will graduate, and if by some ungodly miracle you do, there is definitely no way you will pass your O&Ps.
—But lets say you do. Which would be fucked up, but let’s just humor the possibility for a moment. You pass your O&Ps and are hired by an airline to perform maintenance. Do you honestly think you could do the job right? You - someone who thought the answer was a ringing ball peen hammer. The answer is no. You would make a metallic ring test-related mistake and get hundreds of people killed. People with families and loved ones who trusted you to keep them safe, but you decided to ignore the blatant warning signs and work on planes anyway. I’m disgusted by you. unacceptable…
The test is performed by tapping the repaired surface with edge of a coin. If the repair is sound, the tapping will produce a metallic ringing sound. If there is any void in the material, the tapping will produce a dull, thudding sound.
What two mediums are available for magnetic particle inspection?
The magnetic medium can be applied as either…
A dry oxide powder dusted over the surface, which is often treated with a fluorescent dye that causes it to glow green under a black light, or…
(as is more commonly done) suspended in a light oil such as kerosine and pumped over the surface.
Can aluminum or copper alloys be inspected using the magnetic particle inspection method?
No.
But it’s okay if you thought they could be. We all make mistakes. Just dust yourself off and try again. You’ll get the hang of it!
In order for a part to be inspected using the magnetic particle inspection method, it must be magnetizable. Iron alloys would be acceptable for example.
How is a steel part magnetized and demagnetized?
A steel part is magnetized by holding it in a strong steady magnetic field that aligns all of the magnetic domains in the material.
It is demagnetized by placing it in an AC magnetic field that continually reverses its polarity. This causes the domains to continually reverse their direction. As the domains are reversing, the part is slowly moved from the field so the domains remain in a disoriented state when the demagnetizing force is removed.
Circular Magnetization detects faults where on a part?
Faults that lie parallel to it length.
This includes faults running at 45 degrees.
Circular and longitudinal magnetization inspections compliment each other to cover the entirety of a part.
How and where on a part does longitudinal magnetization defects faults?
It produces a magnetic field that extends lengthwise in the material, detecting faults that extend across the part, perpendicular to the lines of magnetic flux.
This includes faults running at 45 degrees.
Circular and longitudinal magnetization inspections compliment each other to cover the entirety of a part.
Dye Penetrant, eddy current, ultrasonic, and Visual inspections may be used on what materials?
Aluminum forgings and castings.
Magnetic particle inspection can only be used on ferrous materials.
Metallic ring inspection is used to check for delaminations in bonded composite structural materials.
What are the 2 variables for dye penetrant to enter a crack?
Time the penetrant is allowed to remain on the part, and temperature of the part.
When looking for very small cracks, the part can be heated, and the penetrant can be allowed to sit for a longer than normal time.
Dwell time for dye penetrant is determined by the size and shape of the part being inspected. True or False?
False, size and shape of the discontinuities
being looked for is the determinant for dwell time.
A complete inspection using the magnetic particle inspection requires what?
That the part be magnetized twice, longitudinally and circularly, and given two separate inspections.
In order to locate a defect in a part by the magnetic particle inspection method, it is essential that what occurs?
The magnetic lines of force pass approximately perpendicular to the defect. This causes the maximum disruption of the magnetic field and forms magnetic poles which attract the indicating medium across the defect.
During dye penetrant inspection, is developer applied after or before cleaning off dye.
After, the dye must be cleaned off thoroughly before developer is applied or faults will not be as sharp or clear.
Can DC current be used to demagnetize a aircraft part?
Yes. If the direction of the DC is continually reversed. Yes, that sounds like AC. Yes, that is what the study guide says.
What are inclusions in a piece of metal?
Inclusions are impurities trapped inside a piece of metal when it was cast.
When a part is inspected with magnetic particle inspection method, inclusions shows up as fuzzy indications instead of clearly defined faults. Several sets of poles cause the oxide to form in a series of parallel lines.
What are 2 volatile petroleum based solvents ?
Stoddard Solvent & Naphtha
Fatigue Cracks are likely to show up where on a aircraft part?
Where the cross sectional area of the part changes sharply due to being subjected to high concentrations of stress.
Esplain how dye penetrant inspection is performed.
The part to be inspected is thoroughly cleaned and soaked in a liquid penetrant which seeps into any cracks or defects that extend to the surface. After the part is soaked for the required dwell time, the penetrant is washed from the surface, and the surface is covered with a developer which, acting as a blotter, pulls the penetrant from the fault. The penetrant pulled out by the developer shows up as a visible indication.
