2. Before We Start …
Let’s Get Closer:
Name
Position
Work History
Activities
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3. OBJECTIVES
What is NDT?
Know the techniques of NDT.
Safety precautions.
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4. INTRODUCTION
Aircraft maintenance is preventive maintenance.
It is mandatory to identify defect before failure occurs.
It is required to investigate why failure occurs.
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5. NDT METHODS
Optical probes.
Dye penetrants.
Magnetic particles.
Eddy currents.
Radiography.
Ultra-sonics.
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6. OPTICAL PROBES
High intensity light
Mirror
Magnifying glass
Bore scopes
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7. OPTICAL PROBES
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Made of optical fibers
Protected by metallic spiral
Covered by PVC.
8. Uses of optical probes
Compressors
for F.O.D.
surge damage
bearing oil leakage .
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9. Uses of optical probes
Combustion sections
for burning cracks
distortion
carbon build up
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10. Uses of optical probes
Turbine sections
for cracks
dents
nicks
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11. Hazards
Its more safe to use bore scope.
But accompanied hazard may damage the probe or make injury to the user.
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12. Hazards
Heat - let it cool first .
Wind milling - wait till it stops.
Contamination - oil, grease, fuels.
Electrical shocks - along the sheath
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13. Other uses
Structural parts
Hydraulic components
Fuel system components
Electrical components
Pipe lines
Electrical looms
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14. DYE PENETRANT
Basic Process
Put red dye
Leave it for a time (penetrating time)
Clean the surface
Put white developer powder
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15. Fluorescent Dyes
Steps of the test
Use Fluorescent dye.
View cleaned surface under UV light before the application of developer.
After application of the developer, view in a darkened booth under UV light .
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16. Safety Precautions
Don’t look directly into the UV light.
‘Rest your eyes regularly – lengthy viewing will reduce your ability to see clearly and you might miss something.
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17.
18. Magnetic Particle Testing
Basic testing process
Remove the part from the aircraft and clean it down to bare metal.
Demagnetize
Put it between contact heads of the machine
Spray magnetic dust on the part.
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21.
Large Bore Tubes
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Magnetic Particle Testing
22.
Small and Odd shaped items
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Magnetic Particle Testing
23. EDDY CURRENT TESTERS
Applications:
Surface cracks .
Internal corrosion.
Thickness measurement.
Fire damaged skins.
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24. Advantages
The surface need only be cleaned, paint does not need to be stripped off.
Cracks which are full of any other substance will still be detected.
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25. BASIC PRINCIPLES
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In order to generate eddy currents for an inspection a probe is used. Inside the probe is a length of electrical conductor which is formed into a coil.
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BASIC PRINCIPLES
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Alternating current is allowed to flow in the coil at frequency chosen by the technician for type of test involved.
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BASIC PRINCIPLES
A dynamic expanding and collapsing magnetic field forms in and around the coil as the alternating current flows through the coil.
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When an electrically conductive material is placed in the coil’s dynamic magnetic field electromagnetic, induction will occur and eddy currents will be induced in the material
BASIC PRINCIPLES
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When a flaw is introduced to the conductive material, the eddy currents are diturpted.
BASIC PRINCIPLES
30. PROBES
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Different probes are available to detect different types of flaws
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31. PRECAUTIONS
In contact with the surface
Perpendicular to the surface
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32. Applications
Thickness measurement:
The equipment is set up on a test piece of normal thickness.
Any change in thickness results in a deflection of the meter pointer.
Note:
Operator must be aware of the piece geometry.
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33.
Fire Damaged Skins:
When metal is subjected to low temperature damage will not be observed.
Conductivity of the metal will be changed
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Applications
34.
Electro-magnetic spectrum
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RADIOLOGICAL EXAMINATION
This very short wavelength is what gives X- rays and Gamma rays their power to penetrate materials that light cannot.
37. Safety precautions
1.
The less time you spend around a radioactive material the less exposure you will receive.
2.
the greater the distance away from a radioactive source the lesser your exposure to the radiation.
3.
Protect yourself with some type of material to act as a shielding device.
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39. Ultra-Sonic Test
Application:
Flaw detection/evaluation,
Dimensional measurements,
Material characterization, and more.
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40. Ultra-Sonic Test
Components:
the pulser/receiver,
transducer,
and display devices.
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Advantages & Limitations
Advantages
surface and subsurface discontinuities.
The LARGE depth of penetration.
It is highly accurate in determining reflector position and estimating size and shape.
Minimal part preparation is required.
Electronic equipment provides instantaneous results.
43.
Limitations:
Needs a highly skilled and trained.
Coupling medium to promote the transfer of sound energy into the test specimen.
Materials that are rough, irregular in shape, very small are difficult to inspect.
Linear defects oriented parallel to the sound beam may go undetected. Egyptair Training Center
Advantages & Limitations
