Which of the following would indicate a defect in the axle assembly during a pre-trip inspection of a heavy vehicle?

• A. Breaks or cracks in the axle assembly
• B. Worn tire tread on the steering axle
• C. Leaks in air lines
• D. Dirty engine oil

Answer: (A)

During a pre-trip, you focus on the structural integrity of the axle area. A crack or break in the axle assembly is a serious safety defect because it directly compromises the strength and attachment of the wheel. If the axle is damaged, it can fail under load, potentially leading to wheel separation or loss of control, so the vehicle must not be driven until repairs are made.

The other issues relate to different systems: worn tire tread on the steering axle affects traction and steering performance, leaks in air lines involve the braking system, and dirty engine oil points to engine lubrication concerns. None of these indicate a defect in the axle’s structural integrity.