CPE Quality Control & Reliability Engineering 2 — Questions and Answers
Question 1: What is the primary goal of a Failure Mode and Effects Analysis (FMEA)?
- To document failures that have already occurred in production
- To proactively identify potential failure modes and their effects before they occur (Correct answer)
- To calculate the cost of quality failures
- To establish acceptance sampling plans for incoming materials
Correct answer: To proactively identify potential failure modes and their effects before they occur
FMEA is a proactive risk assessment tool used to identify potential failure modes, assess their effects and severity, and prioritize corrective actions before failures occur.
Question 2: In an FMEA, the Risk Priority Number (RPN) is calculated as the product of which three factors?
- Severity, Occurrence, and Detection (Correct answer)
- Frequency, Impact, and Cost
- Probability, Consequence, and Mitigation
- Likelihood, Severity, and Recovery
Correct answer: Severity, Occurrence, and Detection
RPN = Severity × Occurrence × Detection; each factor is rated on a 1–10 scale, and higher RPNs indicate higher-priority failure modes requiring immediate corrective action.
Question 3: What is the primary objective of Reliability-Centered Maintenance (RCM)?
- To perform maintenance on a fixed time-based schedule regardless of condition
- To select the most effective maintenance strategy for each failure mode based on its consequences (Correct answer)
- To eliminate all scheduled preventive maintenance in favor of run-to-failure
- To maximize spare parts inventory to minimize downtime
Correct answer: To select the most effective maintenance strategy for each failure mode based on its consequences
RCM systematically determines the most applicable and cost-effective maintenance strategy for each component and failure mode based on safety, operational, and economic consequences.
Question 4: A p-chart in statistical process control is used to monitor which type of data?
- Continuous measurements such as diameter or weight
- The proportion of nonconforming units in a sample (Correct answer)
- The number of defects per unit on a continuous scale
- Time between successive failures
Correct answer: The proportion of nonconforming units in a sample
A p-chart monitors the proportion (fraction) of nonconforming items in subgroups of varying or fixed sample sizes, making it appropriate for attribute data.
Question 5: What does the fishbone (Ishikawa) diagram help quality engineers identify?
- The statistical distribution of defect data
- The root causes of a problem organized by category (Correct answer)
- The control limits for a process
- The sequence of steps in a manufacturing process
Correct answer: The root causes of a problem organized by category
A fishbone diagram visually maps potential root causes of a problem into categories (commonly: Man, Machine, Method, Material, Measurement, Environment) to support root cause analysis.
Question 6: Mean Time To Repair (MTTR) is best described as:
- The average time between consecutive failures of a system
- The average time required to restore a failed system to operational status (Correct answer)
- The minimum time guaranteed before the next failure
- The total operating time divided by total failures over a period
Correct answer: The average time required to restore a failed system to operational status
MTTR is the average time needed to repair and restore a failed system, including diagnosis, repair, and verification; it directly reflects maintainability.
Question 7: In acceptance sampling, what does the Acceptable Quality Level (AQL) represent?
- The maximum allowable percentage of defects in the entire lot
- The worst acceptable process average of defectives that is still satisfactory to the consumer (Correct answer)
- The minimum sample size required for statistical validity
- The confidence level of the sampling plan
Correct answer: The worst acceptable process average of defectives that is still satisfactory to the consumer
AQL is the maximum percent defective (or defects per hundred units) that can be considered satisfactory as a process average for acceptance sampling purposes.
CPE Quality Control & Reliability Engineering 2
What is the primary goal of a Failure Mode and Effects Analysis (FMEA)?