CRL Failure Analysis and RCA 3

Question 1

Which tool uses top-down Boolean logic (AND/OR gates) to model how combinations of basic events lead to an undesired top event?

Accepted Answer

Fault Tree Analysis (FTA)

Answer

FTA is a deductive, top-down method that uses logic gates to connect basic events to a top event.

Question 2

In a fault tree, an AND gate means the output event occurs when:

Accepted Answer

All input events occur together

Answer

An AND gate requires all inputs to occur at once, which is why redundancy is modeled with AND gates.

Question 3

A fracture surface on a steel bolt shows a dull, fibrous appearance with shear lips and visible necking. This indicates:

Accepted Answer

Ductile overload

Answer

Necking, a fibrous texture, and shear lips are classic signs of ductile overload.

Question 4

Which RCA approach is most effective at preventing hindsight bias during interviews?

Accepted Answer

Asking open-ended questions about what people knew and saw at the time

Answer

Open-ended questions about what was known at the time capture real decision context without biasing recall.

Question 5

A Pareto analysis of 12 months of downtime shows that 3 of 40 failure modes cause 75% of lost production. What should the reliability leader do next?

Accepted Answer

Prioritize RCA and defect elimination on the top 3 failure modes

Answer

Pareto analysis points effort at the vital few causes that drive most of the loss.

CRL - Certified Reliability Leader Practice Test