CAT Maintenance Tools and Equipment 2 — Questions and Answers
Question 1: What is the primary use of dye penetrant inspection (DPI) in aerospace maintenance?
- To detect surface-breaking cracks and defects in non-porous materials (Correct answer)
- To measure material thickness
- To check for internal subsurface voids
- To identify corrosion beneath paint
Correct answer: To detect surface-breaking cracks and defects in non-porous materials
Dye penetrant inspection uses a colored or fluorescent penetrant that seeps into surface-breaking defects, revealing cracks and porosity on the surface of non-porous materials after developer is applied.
Question 2: When is Magnetic Particle Inspection (MPI) preferred over dye penetrant for detecting defects?
- When inspecting ferromagnetic materials for both surface and near-surface defects (Correct answer)
- When inspecting aluminum components for corrosion
- When checking composite panels for delamination
- When testing titanium fasteners for surface cracks only
Correct answer: When inspecting ferromagnetic materials for both surface and near-surface defects
MPI is preferred for ferromagnetic materials (iron, steel, nickel alloys) because it detects both surface and near-surface discontinuities using magnetic fields and iron particles.
Question 3: What type of NDT method uses high-frequency sound waves to detect internal defects in aircraft structures?
- Ultrasonic Testing (UT) (Correct answer)
- Eddy Current Testing
- Radiographic Testing
- Thermographic Inspection
Correct answer: Ultrasonic Testing (UT)
Ultrasonic Testing sends high-frequency sound waves through material and analyzes reflections to detect internal voids, cracks, inclusions, and delaminations in both metallic and composite structures.
Question 4: What is the correct application sequence for dye penetrant inspection?
- Clean surface → Apply penetrant → Dwell time → Remove excess → Apply developer → Inspect (Correct answer)
- Apply penetrant → Clean surface → Apply developer → Inspect
- Apply developer → Apply penetrant → Inspect → Clean surface
- Clean → Apply developer → Apply penetrant → Inspect
Correct answer: Clean surface → Apply penetrant → Dwell time → Remove excess → Apply developer → Inspect
Proper DPI sequence is: clean and dry the surface, apply penetrant, allow dwell time for penetration, remove excess penetrant, apply developer to draw out penetrant, then inspect under appropriate lighting.
Question 5: What is the primary advantage of eddy current testing (ECT) in aerospace inspections?
- It can detect cracks and corrosion in conductive materials through coatings and paint without surface preparation (Correct answer)
- It works on composite materials without any contact
- It provides three-dimensional imaging of internal defects
- It measures material hardness accurately
Correct answer: It can detect cracks and corrosion in conductive materials through coatings and paint without surface preparation
Eddy current testing induces electromagnetic currents in conductive materials and detects disruptions caused by cracks or corrosion, often through surface coatings without requiring paint removal.
Question 6: What purpose does a go/no-go gauge serve in aerospace parts inspection?
- To verify that a part dimension falls within the acceptable tolerance range without providing a specific measurement (Correct answer)
- To measure exact part dimensions with high precision
- To test the tensile strength of threaded fasteners
- To check surface finish roughness
Correct answer: To verify that a part dimension falls within the acceptable tolerance range without providing a specific measurement
A go/no-go gauge confirms whether a dimension is within tolerance: the 'go' end should fit (minimum acceptable size), and the 'no-go' end should not fit (maximum acceptable size).
CAT Maintenance Tools and Equipment 2
What is the primary use of dye penetrant inspection (DPI) in aerospace maintenance?