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Specializing in
Aircraft NDT

inspections since 1996



Level III NDT

F.A.A. Repair Station N5DR176O

 

Phone: (650) 654-3601
Fax:    (650) 574-9198

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NDT Terminology


Ultrasonic AScan Picture

Ultrasonic Testing


Ultrasonic Testing

In ultrasonic testing, ultra-high frequency sound waves are transmitted into a material to detect imperfections within the material, or changes in material properties. The pulse echo technique is accomplished by introducing sound into the test object and reflections (echoes) are returned to a receiver from internal imperfections or from geometrical surfaces of the part. It is typically used to detect subsurface defects, or defects originating from surfaces not accessible without disassembly or removal.  It can also be used to detect laminations, lack of fusion, and corrosion of various materials.
 

Eddy Current Image

Eddy Current


Eddy Current

With the eddy current method, electrical currents are generated into a conductive material by an induced, varying magnetic field. Imperfections or changes in a materialís conductive properties cause interruptions in the flow of these electrical (eddy) currents. This results in changes in the induced magnetic field, which is monitored, and indicates the presence of a change in the test object. The eddy current method is used extensively to inspect aircraft skin and structure for very small surface breaking flaws and can successfully detect sub-surface discontinuities.  This methodology is also used in the sorting of metal alloys as well as precisely determining the thickness of various coatings.
 

Visual Inspection


Visual Inspection

The oldest and most common method of NDT, visual examination has numerous applications. It has even been traced back to the book of Genesis! Visual techniques are used in conjunction with all other NDT methods, but may be used as the primary inspection method. The inspection of a turbine engine hot section using flexible or rigid borescopes is an example of the visual testing method.
 

Magnetic Particle Indication

Magnetic Particle


Magnetic Particle

Magnetic Particle inspection is conducted on ferro-magnetic material by inducing a magnetic field into the test part and coating the surface with iron particles (either dry or suspended in a liquid). Surface imperfections will distort the magnetic field causing an accumulation of the iron particles near imperfections, thus indicating their presence.

 

Liquid Penetrant Exams

Liquid Penetrant


Liquid Penetrant

Liquid penetrant inspections are only able to detect surface breaking flaws.
The specimen is coated with a fluorescent or visible dye solution. After a specified dwell time, the excess penetrant is removed from the surface. Often, a developer is applied to help draw penetrant out of imperfections open to the surface, making them much more visible. With fluorescent penetrants, an ultraviolet lamp causes the indications to fluoresce brightly, greatly increasing the visibility of the flaw. Liquid penetrant inspections are only able to detect surface breaking flaws.
 

Xray of Pipe

Radiography


Radiography

An X-ray machine, or radioactive isotope is used as a source of radiation. The radiation is directed through the test part and onto a recording media (often film). When the film is developed, a radiograph is obtained that can show the internal condition of a part. Possible imperfections show up as density changes (a difference in blackening between two adjacent areas) in the film. Cracks, porosity, lack of fusion and tungsten inclusions in welds are but a few of the examples of possible flaws that may be revealed.