CMRT Corrective Maintenance Procedures 3 — Questions and Answers
Question 1: Which root cause analysis tool uses a series of 'why' questions to drill down to the underlying cause of an equipment failure?
- Pareto chart
- 5 Whys analysis (Correct answer)
- Fishbone (Ishikawa) diagram only
- Gantt chart
Correct answer: 5 Whys analysis
The 5 Whys technique iteratively asks 'why' until the physical, human, and latent root causes of a failure are identified.
Question 2: When reinstalling a press-fit bearing on a shaft using the correct corrective maintenance procedure, heat or a hydraulic press should be used to:
- Expand the inner race slightly so it slides on without damaging the rolling elements (Correct answer)
- Melt the bearing grease before installation
- Stretch the outer race to match the housing bore
- Harden the shaft surface before fit-up
Correct answer: Expand the inner race slightly so it slides on without damaging the rolling elements
Heating the inner race causes it to expand, allowing installation without transmitting force through the rolling elements, which would damage them.
Question 3: A technician notices a motor running hotter than normal after completing a corrective bearing replacement. The MOST likely cause is:
- The motor has too many poles
- Over-greasing the bearing, which causes churning and excessive heat (Correct answer)
- The supply voltage is too low by exactly 1 volt
- The motor frame is painted the wrong color
Correct answer: Over-greasing the bearing, which causes churning and excessive heat
Over-greasing is one of the most common causes of premature bearing failure and motor heat; excess grease churning increases friction and temperature.
Question 4: After completing corrective maintenance on a hydraulic system, which test should be performed BEFORE returning the system to normal operating pressure?
- A full load production run immediately
- A low-pressure leak check to verify all connections and seals are secure (Correct answer)
- Bleed the system at maximum pressure only
- Drain and refill the reservoir with water first
Correct answer: A low-pressure leak check to verify all connections and seals are secure
A low-pressure leak check allows technicians to identify and correct any connections or seals that were disturbed before exposing the system to full pressure.
Question 5: In corrective maintenance, the term 'failure mode' refers to:
- The financial cost of the failure event
- The specific way in which a component or system ceases to perform its required function (Correct answer)
- The production schedule impact of the downtime
- The technician's shift assignment during the failure
Correct answer: The specific way in which a component or system ceases to perform its required function
A failure mode describes the observable condition (e.g., seizure, fracture, corrosion) by which an item fails to meet its performance requirement.
Question 6: When a corrective maintenance work order is classified as 'emergency,' what distinguishes it from a 'priority' work order?
- Emergency WOs are planned at least 48 hours in advance
- Emergency WOs address immediate safety hazards or total production stoppages requiring immediate response (Correct answer)
- Emergency WOs are always lower cost than priority WOs
- Emergency WOs require supervisor approval only after the work is done
Correct answer: Emergency WOs address immediate safety hazards or total production stoppages requiring immediate response
Emergency work orders represent unplanned failures with immediate safety or production consequences that cannot wait for normal scheduling.
Question 7: A technician is troubleshooting vibration on a fan assembly after a corrective blade replacement. High 1x vibration is found. This most likely indicates:
- Bearing race defect on the inner race
- Rotor imbalance requiring balancing correction (Correct answer)
- Resonance in the electrical supply frequency
- Oil whip in the fan shaft bearing
Correct answer: Rotor imbalance requiring balancing correction
Vibration at 1x running speed (1x RPM) is the classic signature of unbalance, which is common after blade replacement if the new blade weight differs from the original.
CMRT Corrective Maintenance Procedures 3
Which root cause analysis tool uses a series of 'why' questions to drill down to the underlying cause of an equipment failure?