FAA Aviation Mechanic Airframe (AMA)Airframe InspectionMedium
A technician wants to inspect the interior surface of a wing rear spar for corrosion without removing the wing skin. Which inspection tool is best suited for this task?
- AMagnetic particle yoke
- BFeeler gauge set
- CBorescope
- DDye penetrant kit
Show answer & explanationAnswer & explanation
Correct answer: C. Borescope
A borescope allows visual inspection of internal structures such as spar interiors, fuel tanks, and closed cavities through small access holes without disassembling the structure. Dye penetrant and magnetic particle testing require direct surface access, and a feeler gauge measures gaps, not internal corrosion.
Why the other options are wrong
- A. Magnetic particle inspection needs direct surface contact and only works on ferrous metals.
- B. A feeler gauge measures clearances, not internal corrosion.
- D. Dye penetrant requires direct access to the surface being tested, not hidden internal areas.
Borescope Inspection
A visual NDT method using a rigid or flexible optical device inserted through small access points to inspect internal structures without disassembly.
- Used for spars, fuel tanks, engine interiors
- Minimizes need for structural disassembly
- Can be rigid or flexible fiber-optic/video type
Memory trick: Borescope = 'periscope for the inside of the plane'