ASEP System Safety and Reliability Engineering 1 — Questions and Answers
Question 1: What does 'reliability' mean in the context of systems engineering?
- The ability of a system to perform its required function under stated conditions for a specified period of time (Correct answer)
- The cost of maintaining a system over its lifetime
- The degree to which a system meets stakeholder expectations
- The number of personnel required to operate a system
Correct answer: The ability of a system to perform its required function under stated conditions for a specified period of time
Reliability is defined as the probability that a system performs its required function under stated conditions for a specified time period.
Question 2: In systems engineering, what is a Failure Mode and Effects Analysis (FMEA) used for?
- Scheduling maintenance intervals
- Identifying potential failure modes and assessing their impact on system performance (Correct answer)
- Generating test cases for software
- Documenting interface requirements
Correct answer: Identifying potential failure modes and assessing their impact on system performance
FMEA systematically identifies potential failure modes, determines their effects, and prioritizes them so engineers can mitigate the most critical risks.
Question 3: What does 'Mean Time Between Failures' (MTBF) measure?
- The time required to repair a failed system
- The average time a repairable system operates between successive failures (Correct answer)
- The total system life expectancy
- The time from system activation to first failure only
Correct answer: The average time a repairable system operates between successive failures
MTBF is the average operating time between successive failures for a repairable system, and is a key reliability metric.
Question 4: In a fault tree analysis (FTA), the top-level event represents:
- The most likely component failure
- The undesired system-level event that the analysis seeks to prevent (Correct answer)
- The first maintenance action required
- A cost overrun scenario
Correct answer: The undesired system-level event that the analysis seeks to prevent
In FTA, the top event is the undesired outcome (e.g., system failure) that engineers analyze by tracing down to root causes.
Question 5: Which of the following is a key difference between safety and reliability?
- Safety applies only to hardware; reliability applies to software
- Safety focuses on preventing hazardous outcomes; reliability focuses on consistent performance over time (Correct answer)
- Reliability is only measured during testing; safety is measured in operation
- There is no difference; they are the same concept
Correct answer: Safety focuses on preventing hazardous outcomes; reliability focuses on consistent performance over time
Safety is concerned with preventing hazards that could cause harm, while reliability is concerned with the system's ability to perform consistently over time.
Question 6: What is a 'hazard' in systems engineering safety terminology?
- A design defect found during testing
- A condition or state that could lead to an undesired event causing harm (Correct answer)
- A cost risk identified in the budget
- A performance requirement not yet verified
Correct answer: A condition or state that could lead to an undesired event causing harm
A hazard is a condition or state that, if left uncontrolled, could lead to an accident or undesired event causing harm to people, property, or the environment.
ASEP System Safety and Reliability Engineering 1
What does 'reliability' mean in the context of systems engineering?