AERA Component Inspection & Quality Control 2 — Questions and Answers
Question 1: When checking a crankshaft for straightness, which measuring instrument is used in conjunction with V-blocks?
- Micrometer
- Dial indicator (Correct answer)
- Feeler gauge
- Bore gauge
Correct answer: Dial indicator
A dial indicator mounted over the crankshaft journal while it rests in V-blocks reveals runout (bend) in the shaft.
Question 2: Which condition is indicated when a cylinder bore shows greater wear at the top of the ring travel than at the bottom?
- Taper (Correct answer)
- Out-of-round
- Scoring
- Glazing
Correct answer: Taper
Taper occurs because combustion pressure forces the rings hardest against the bore at the top of the stroke, causing more wear there.
Question 3: A main bearing bore that measures larger on one axis than on the perpendicular axis is described as:
- Tapered
- Out-of-round (Correct answer)
- Undersize
- Oversize
Correct answer: Out-of-round
Out-of-round (also called ovality) means the bore is not a true circle, with differing diameters at 90-degree angles.
Question 4: Magna-flux (magnetic particle) inspection is primarily used to detect which type of defect in engine components?
- Surface or near-surface cracks in ferrous metals (Correct answer)
- Porosity in aluminum castings
- Hardness variations across a surface
- Dimensional out-of-spec conditions
Correct answer: Surface or near-surface cracks in ferrous metals
Magnetic particle inspection reveals surface and subsurface cracks in ferrous (iron-based) components by highlighting particle accumulation at flux leakage points.
Question 5: What is the maximum allowable out-of-round condition for most production engine cylinder bores before reconditioning is required?
- 0.0005 in (0.013 mm)
- 0.003 in (0.076 mm)
- 0.001 in (0.025 mm) (Correct answer)
- 0.005 in (0.127 mm)
Correct answer: 0.001 in (0.025 mm)
Most manufacturers specify a maximum out-of-round of 0.001 in (0.025 mm); beyond this, boring or honing to restore roundness is required.
Question 6: When pressure-testing a cylinder head for coolant leaks, what medium is typically used to reveal cracks?
- Pressurized coolant at operating temperature
- Compressed air with the head submerged in water (Correct answer)
- Vacuum with dye penetrant applied
- Steam at 30 psi
Correct answer: Compressed air with the head submerged in water
Compressed air is applied to sealed coolant passages while the head is submerged; escaping bubbles pinpoint any cracks or porosity.
Question 7: Which measurement confirms that a connecting rod has not been twisted (side-to-side misalignment)?
- Rod length center-to-center
- Rod twist checked on an alignment fixture (Correct answer)
- Big-end bore diameter
- Small-end pin bore diameter
Correct answer: Rod twist checked on an alignment fixture
A connecting rod alignment fixture checks both bend and twist by placing the rod on mandrels and measuring deviation at the pin ends.
AERA Component Inspection & Quality Control 2
When checking a crankshaft for straightness, which measuring instrument is used in conjunction with V-blocks?