How to Complete a New RCS Instant Reliability Analysis for Repairable Spares

How to Complete a New RCS Instant Reliability Analysis for Repairable Spares

Completing the Instant Reliability Analysis

Instantaneous Reliability is the probability that a spare is available at any given moment in time or the probability of having a spare at hand when needed.
  1. Select New RCS Analysis on the ACTOR index page.


  1. Capture the Analysis Name.

  1. Select the search icon to find the part that you wish to conduct an analysis on. A pop-up will appear with a list of Parts that can be selected.

  1. Select the applicable part from the Part Look-up table.
  2. Click the Select button at the bottom of the pop-up as illustrated below.


  1. Select the Insurance option from the dropdown.


  1. Select the Repairable radio button.


Current Spare Stock Policy

  1. Expand the Current Spare Stock Policy section.
  2. Capture the minimum and maximum stock levels required for the particular non-repairable spare equipment as prescribed by the applicable policy/policies.


  1. Depending on the values entered, ACTOR will calculate the Reorder Point and the Order Quantity.
    1. The Reorder Point- The reorder point is the minimum quantity of a spare part or inventory that must be on hand at all times to ensure there is no interruption in supply. It is used to determine when to replenish inventory to avoid stockouts.
    2. Order Quantity- The order quantity refers to the amount of a spare part or inventory that is ordered when the inventory level drops to or below the reorder point.

Usage Per Time

  1. Now expand the Usage Per Time section to capture the frequency of usage for the particular spare equipment.
  2. If there is historical usage data available for a particular spare, the user can import the data directly into ACTOR by selecting the browse button.

  1. Locate the file you wish to upload and select open, and the values will be displayed in the grid.
  2. If there is no historical data, users can manually capture the frequency of usage by selecting the Add button.

  1. Capture the frequency of usage value.
  2. Select the Update button. You will then receive a confirmation pop-up to save the changes.
  3. Select OK and the changes will be saved.

  1. Select the Time Unit.
  2. Click the Calculate button and ACTOR will automatically calculate the Average Demand Per Unit of Time as well as the Standard Deviation. The results are visually displayed in a graph called a bell curve which shows the distribution of usage patterns over time.

    1. Average Demand Per Unit of Time- This refers to the average rate at which spare parts are used or consumed over a specific period. This average usage per time helps in determining reorder points, setting inventory levels, and predicting future needs based on historical usage patterns.
    2. Standard Deviation- The standard deviation is a measure of the amount of variation or dispersion of a set of values. A low standard deviation indicates that the values tend to be close to the mean (also called the expected value) of the set, while a high standard deviation indicates that the values are spread out over a wider range.

Input Parameters

  1. Expand the Input Parameters section.
  2. Select the Decision Criteria otherwise also known as the Stock Level Criteria from the dropdown. In this case the user will select Instant Reliability.

  1. Capture the number of Parts in Use. Number of parts in operation, which their failure can cause equipment downtime.
  2. Capture the Mean Time to Repair. Mean Time to Repair (MTTR) refers to the average time taken to repair an item or system after a failure occurs.
  3. Capture the Demand Rate. This value will automatically be calculated using the Average Demand Per Unit of Time if there is historical usage data that was captured. If there is no history then a demand rate figure needs to be decided on or determined by the client based on best knowledge at the time and manually entered.
  4. The Unit of Time will be pre-selected based on your selection in the Usage Per Time section.
  5. Capture the Current Spares in Stock (If applicable). This is the actual number of inventory in holding.


  1. Make a decision between Reliability Required or Spare in Stock, for each selection the other option will be greyed out.

Understanding the Required Availability Approach:

The Reliability Required is a value from 0-100%. It refers to the level of reliability or availability that is deemed necessary for the equipment or systems being supported by spare parts.
  1. Select the Reliability Required radio button for your calculation.
  2. Capture the Reliability Required %.

  1. Click Calculate and the results will be displayed at the bottom of the screen. The results are broken down into different sections:
    1. Calculated Result- This result shows the total cost of spares based on the actual spare holding.
    2. Current Practice- This result shows the total cost of spares based on the optimal spare holding as prescribed by a particular policy.
    3. Spares +1 Scenario- This result shows the total cost of holding 1 extra spare more than the optimal spare holding.
    4. Spares -1 Scenario- This result shows the total cost of holding 1 less spare than the optimal spare holding.
  2. Click the Save button.

Understanding the Spare in Stock Approach

Spare in Stock- This refers to costs associated with holding a suggested number of spare parts depending on an organizations financial situation at any given point in time. This calculation provides a view of the financial implications of holding less or more spare parts than the optimal spare holding.
  1. Select the Stock in Spare radio button for your calculation.
  2. Capture the number of Spares in Stock.
  3. Click Calculate and the results will be displayed at the bottom of the screen as explained in the section above.
  4. Do not forget to Save the analysis.