FAA Aviation Mechanic Airframe (AMA)Airframe InspectionEasy
A technician suspects a fatigue crack on the surface of an aluminum wing skin but sees no visible crack. Which nondestructive inspection method is best suited to detect this surface crack on nonferrous, non-magnetic material?
- AVisual inspection with a flashlight
- BX-ray radiography only
- CDye penetrant inspection
- DMagnetic particle inspection
Show answer & explanationAnswer & explanation
Correct answer: C. Dye penetrant inspection
Dye penetrant inspection works on nonferrous, non-magnetic materials like aluminum to reveal surface-breaking cracks by allowing dye to seep into the crack and then be drawn out by a developer.
Why the other options are wrong
- A. A flashlight alone cannot reveal a fine surface crack invisible to the naked eye
- B. X-ray is used for subsurface defects and is more complex/costly for this purpose
- D. Magnetic particle inspection only works on ferromagnetic materials, not aluminum
Dye Penetrant Inspection
An NDT method using colored or fluorescent liquid dye to detect surface-breaking defects in nonporous, non-magnetic materials.
- Works on aluminum, magnesium, titanium, and other nonferrous metals
- Steps: clean, apply penetrant, remove excess, apply developer, inspect
- Cannot detect subsurface flaws, only surface-breaking ones
Memory trick: Dye stains the surface secret; magnets grab only iron