CMRP Root Cause Analysis and Failure Investigation 1 — Questions and Answers
Question 1: In root cause analysis, what is a 'physical root cause'?
- The material or mechanical failure mechanism that directly caused the failure event (Correct answer)
- The management decision that allowed the failure to occur
- The operating error that triggered the failure
- The missing procedure that failed to prevent the failure
Correct answer: The material or mechanical failure mechanism that directly caused the failure event
A physical root cause is the tangible, material-level mechanism—such as fatigue, corrosion, or overload—that was the proximate cause of the failure.
Question 2: What does the '5 Whys' technique aim to achieve in failure analysis?
- Iteratively asking 'why' to drill through symptoms to the underlying root cause (Correct answer)
- Identifying five separate causes for a single failure event
- Ranking five possible failure modes by probability
- Documenting five corrective actions for each failure
Correct answer: Iteratively asking 'why' to drill through symptoms to the underlying root cause
The 5 Whys technique peels back layers of symptoms by repeatedly asking why each condition exists, aiming to reach the true systemic or human root cause.
Question 3: Which RCA tool uses a visual diagram resembling a fish skeleton to organize causes by category?
- Ishikawa (fishbone) diagram (Correct answer)
- Fault tree analysis
- Pareto chart
- Failure modes and effects analysis
Correct answer: Ishikawa (fishbone) diagram
The Ishikawa diagram (also called a fishbone or cause-and-effect diagram) organizes potential causes into categories such as Machine, Method, Material, Man, Measurement, and Environment.
Question 4: In CMRP terminology, what is a 'latent root cause'?
- An underlying organizational or systemic weakness that allows physical and human root causes to exist (Correct answer)
- A failure cause that appears only after long periods of operation
- A root cause hidden within electrical wiring or conduit
- A cause identified only through laboratory analysis
Correct answer: An underlying organizational or systemic weakness that allows physical and human root causes to exist
Latent root causes are the systemic, managerial, or cultural conditions (e.g., inadequate training, missing procedures) that enable failures to occur and recur.
Question 5: What is the primary purpose of a failure reporting, analysis, and corrective action system (FRACAS)?
- To systematically capture, analyze, and resolve failures so corrective actions prevent recurrence (Correct answer)
- To track technician response times to breakdowns
- To manage spare parts procurement after failures
- To calculate financial losses from equipment downtime
Correct answer: To systematically capture, analyze, and resolve failures so corrective actions prevent recurrence
FRACAS creates a closed-loop process: failures are reported, analyzed for root causes, and corrective actions are implemented and verified to prevent recurrence.
Question 6: Which failure analysis technique uses a top-down, deductive logic diagram to identify all possible causes of a defined undesirable event?
- Fault tree analysis (FTA) (Correct answer)
- Failure modes and effects analysis (FMEA)
- Event tree analysis
- Bow-tie analysis
Correct answer: Fault tree analysis (FTA)
Fault tree analysis starts with a defined top-level failure event and uses Boolean logic gates (AND/OR) to systematically map all combinations of lower-level causes that could lead to it.
CMRP Root Cause Analysis and Failure Investigation 1
In root cause analysis, what is a 'physical root cause'?