Risk Management & Maintenance Flashcards

Which quantitative risk metric represents the probability of an individual being harmed per year due to a specific hazard?

Answer: Individual risk

Individual risk is expressed as the annual probability that a specific person will be harmed by the hazard.

In FMECA, the Criticality Number (Cm) is calculated by multiplying failure mode ratio, failure rate, and:

Answer: Mission time

Cm = failure mode ratio × item failure rate × mission time, giving the expected number of critical failures per mission.

The concept of 'safe-life' in maintenance refers to a component that:

Answer: Is replaced at a fixed interval before expected failure

Safe-life components are retired at a predetermined usage limit to prevent in-service failure regardless of apparent condition.

An FTA uses which logic gate to represent a condition where ALL inputs must occur for the output event to occur?

Answer: AND gate

An AND gate in a Fault Tree requires all input events to be TRUE simultaneously for the output event to occur.

Which maintenance performance metric measures the proportion of total time that a system is available for use?

Answer: Availability

Availability = Uptime / (Uptime + Downtime), representing the fraction of time the system is in a functioning state.

In risk management, the hierarchy of controls places which option as the most effective risk reduction method?

Answer: Elimination of the hazard

Elimination removes the hazard entirely and is the most effective control because it makes risk zero at the source.

A system has MTTF = 1000 hours and MTTR = 50 hours. What is the steady-state availability?

Answer: 0.952

Availability = MTTF / (MTTF + MTTR) = 1000 / (1000 + 50) = 1000/1050 ≈ 0.952.