Question

A quantitative measure of maintainability is
1. Downtime
2. Mean Time Between Failure
3. Mean Time To Repair
4. System availability

Answer 1

Correct Answer - Option 3 : Mean Time To Repair

Explanation:

• Reliability, availability, and maintainability (RAM) are three system attributes that systems engineers, logisticians, and users are all interested in. They have an impact on a system's economic life-cycle costs and utility when taken together.

Reliability:

• It is defined as the probability of a system or system element performing its intended function without failure for a specified period of time under specified conditions.

• The probability of a component surviving until time t is referred to as reliability. Its complement is the probability of failure before or at time t. If we define a random variable T as the time to failure, then:
  R(t) = P(T > t) = 1 - F(t), where R(t) is the reliability and F(t) is the failure probability.

Maintainability:

• Defined as the likelihood that a system or system element can be repaired in a defined environment within a given time frame.
• Maintainability is characterized by the mean time needed to return equipment to operating condition, the probability of returning equipment to working condition within a given period of time.

Availability:

• It is defined as a repairable system or system element's probability of being operational at a given point in time under a given set of environmental conditions. The availability of a system is determined by its reliability and maintainability.