Preventive Maintenance and Inspection Flashcards

A technician is inspecting flexible air lines on a truck's brake system and finds a line with a small crack in the outer jacket but no visible damage to the inner tube. What is the correct action?

Answer: Replace the hose immediately regardless of inner tube condition

Any cracked or damaged brake air hose must be replaced immediately because the outer jacket protects the inner tube from abrasion and further deterioration.

During a PM inspection, the engine air filter restriction gauge shows a reading in the red zone. What is the correct procedure?

Answer: Replace the air filter element and reset the restriction indicator

A restriction indicator in the red zone confirms the filter element is plugged beyond serviceable limits and must be replaced, not cleaned.

When checking the fifth wheel on a semi-truck during a PM inspection, what is being verified when the technician pulls on the kingpin release handle with the trailer coupled?

Answer: That the locking mechanism is fully engaged and cannot be accidentally released

Pulling the kingpin release handle while coupled confirms the locking jaws are fully engaged and will not inadvertently release under load.

A coach technician notices the DEF (Diesel Exhaust Fluid) level sensor reads correctly but the DEF appears amber in color instead of clear. What should the technician do?

Answer: Drain and replace the DEF, as contaminated fluid can damage the SCR catalyst

DEF should be clear; amber discoloration indicates contamination that can crystallize in and damage the expensive SCR injector and catalyst.

During a PM inspection of a heavy truck, a technician finds the front axle U-bolt nuts have been improperly torqued — one nut is 40 ft-lb below specification. What is the risk of operating with this condition?

Answer: Axle shift, wheel misalignment, and potential loss of vehicle control

Improperly torqued U-bolt nuts allow the axle to shift position, causing sudden severe misalignment and potential loss of steering control.

A technician is performing a PM on a bus and checks the wheelchair lift. The platform descends correctly but will not rise with a 200 lb test load. What is the FIRST system to inspect?

Answer: Hydraulic fluid level and pump pressure output

Inability to lift a rated load under hydraulic pressure most directly points to low fluid level or insufficient pump pressure as the first diagnostic step.

When inspecting tire tread depth on a steer axle during a PM inspection, what is the minimum tread depth allowed before the tire must be replaced per FMCSA regulations?

Answer: 4/32 inch

FMCSA requires a minimum of 4/32 inch tread depth on steer axle tires, which is more stringent than the 2/32 inch requirement for other axle positions.