CQE Reliability and Risk Management

Question 1

What does the 'bathtub curve' in reliability engineering represent?

Accepted Answer

The failure rate pattern showing infant mortality, useful life, and wear-out phases

Answer

The bathtub curve depicts three phases of product failure rate: early failures (infant mortality), random failures during useful life, and increasing failures during wear-out.

Question 2

Mean Time Between Failures (MTBF) is a reliability metric applicable to:

Accepted Answer

Repairable items that can be restored to service

Answer

MTBF applies to repairable systems and represents the average time between successive failures after repair, distinct from MTTF (Mean Time To Failure) used for non-repairable items.

Question 3

In a Failure Mode and Effects Analysis (FMEA), the Risk Priority Number (RPN) is calculated as:

Accepted Answer

Severity × Occurrence × Detection

Answer

RPN is the product of three ratings: Severity (impact of failure), Occurrence (likelihood of cause), and Detection (ability to detect before reaching customer), each typically rated 1–10.

Question 4

What is the primary purpose of a Fault Tree Analysis (FTA)?

Accepted Answer

To identify combinations of events that could lead to a top-level undesired event

Answer

FTA is a top-down, deductive analysis that uses Boolean logic to identify all possible combinations of hardware failures, human errors, and external events that could cause a specific undesired top event.

Question 5

In reliability testing, accelerated life testing (ALT) is used to:

Accepted Answer

Expose products to stresses above normal levels to induce failures faster and predict life

Answer

ALT applies elevated stress levels (temperature, voltage, vibration) to precipitate failures in a shorter time, allowing engineers to extrapolate reliability performance under normal use conditions.

CQE - Certified Quality Engineer Practice Test

CQE - Certified Quality Engineer Practice Test

CQE Reliability and Risk Management