The visual inspection instructions of a maintenance task specified not to use an LED flashlight why? Is the white color of the light detrimental to a visual inspection, are they too bright does the frequency of light block the detection of cracks or shadows?
I don't think Robert has it right because the procedure states if cracks were detected or suspected to perform a dye penetrant inspection.
Dan B
Favorite Answer
nm = nanometers.
White LED lights are made up of the three primary colors (Red - 650 nm, Green - 575 nm and Blue - 475 nm). The lights are combined to make white. LEDs emit light in an extremely narrow wavelength.
Surfaces that reflect light outside the 450-675 nm range would not reflect any light when using an LED. Also, any surfaces that would reflect light in the 525 nm range would also not be visible.
Incandescent light emits light in a very wide spectrum throughout the visible light spectrum. Visible light is in the 380 - 770 nm range. So a white LED would not reflect light between 380 nm - 425 nm and 675 nm - 770 nm along with a narrow band near 525 nm.
Anonymous
1
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Inspection Flashlight
Robert
It could be because the inspector could see "way better" with the LED. Complex inspection procedures tell the inspector what to accept and what to reject. The engineers will write the specification such that "Any cracks that can be seen with the naked eye and using an incandescent light is a reject." So if an LED was used the inspector could see cracks that were invisible using an incandescent light. In this case a good part would be rejected. Makes ya feel really safe when flying the "Friendly Skies"
Anonymous
Some colours (like red) are rendered poorly by LED light. Also, the light rapidly diminishes with distance and cannot be as effectively 'focused' as incandescent or fluorescent light.