ITMC Preventive Maintenance & Troubleshooting 5 — Questions and Answers
Question 1: A plant's maintenance records show a component failing repeatedly every 3–4 months. The BEST long-term corrective action is to:
- Increase the PM interval to match the failure frequency
- Perform root cause analysis (RCA) to eliminate the underlying cause (Correct answer)
- Stock more spare parts to reduce downtime
- Assign a dedicated technician to monitor that component
Correct answer: Perform root cause analysis (RCA) to eliminate the underlying cause
Repetitive failures indicate an unresolved root cause; RCA identifies and eliminates the underlying problem rather than just managing the symptom.
Question 2: What is the recommended minimum distance between a motor shaft coupling and a technician's body during operation, per general industrial safety practice?
- 6 inches
- Maintain a safe distance with all guards in place — never operate without guards (Correct answer)
- 18 inches
- 3 feet
Correct answer: Maintain a safe distance with all guards in place — never operate without guards
OSHA and industrial safety standards require rotating coupling guards to be in place during operation; no specific distance substitutes for proper guarding.
Question 3: A technician observes that a newly installed chain drive is noisy and vibrating excessively. After verifying correct alignment, the NEXT most likely cause to check is:
- Motor overload
- Excessive chain slack or incorrect chain pitch (Correct answer)
- Sprocket material incompatibility
- Insufficient motor horsepower
Correct answer: Excessive chain slack or incorrect chain pitch
Excessive chain slack causes the chain to slap and vibrate; incorrect pitch causes the chain not to mesh properly, both resulting in noise and vibration.
Question 4: In ultrasonic testing used for PM, what condition is indicated by a high-pitched hissing sound detected from a compressed air line fitting?
- Normal turbulent flow
- A leak at the fitting (Correct answer)
- Over-pressurization of the line
- Cavitation inside the valve
Correct answer: A leak at the fitting
Ultrasonic detectors pick up the high-frequency hissing sound produced by turbulent air escaping through a leak at fittings, valves, or seals.
Question 5: A technician checks a roller bearing using a stethoscope and hears a regular clicking sound that increases with speed. This symptom is MOST consistent with:
- Normal bearing noise
- A defective rolling element (spalled ball or roller) (Correct answer)
- Insufficient lubrication
- Shaft misalignment
Correct answer: A defective rolling element (spalled ball or roller)
A regular clicking or ticking that scales with shaft speed is characteristic of a damaged rolling element contacting the race once per revolution.
Question 6: When draining and replacing hydraulic fluid as part of a PM schedule, the MOST important step before refilling is:
- Pressurizing the system to flush remaining fluid
- Flushing the system and replacing all hydraulic filters (Correct answer)
- Adding the new fluid directly to the partially drained reservoir
- Running the system at full load immediately after refill
Correct answer: Flushing the system and replacing all hydraulic filters
Flushing removes contaminated fluid and degraded particles, while replacing filters prevents old contamination from immediately degrading the fresh fluid.
Question 7: A maintenance team implements a 5-Why analysis after an unexpected equipment failure. The purpose of this technique is to:
- Document equipment downtime for insurance purposes
- Systematically trace a problem back to its root cause by asking 'why' repeatedly (Correct answer)
- Determine which technician was responsible for the failure
- Estimate the cost of repair before beginning work
Correct answer: Systematically trace a problem back to its root cause by asking 'why' repeatedly
The 5-Why technique iteratively asks 'why' at each level of a problem to move past symptoms and identify the true root cause driving the failure.
ITMC Preventive Maintenance & Troubleshooting 5
A plant's maintenance records show a component failing repeatedly every 3–4 months.
The BEST long-term corrective action is to: