WF12: Conduct Reliability Allocation

Pre-requisites

• RAM Module: access to Reliability, Availability & Maintainability (RAM) module enables Reliability Allocation.
• MADE Project: consists of FBD model items further defined with mission profiles.

Detailed Descriptions (numbered steps)

1. Access Reliability Allocation (RA) Editor under 'Analyses' in the main menu bar.
2. Select the 'Plus' icon to create a new Reliability Allocation Analysis and define the analysis details accordingly.
3. Set the Target Reliability using the available options or entering a custom value, as required.
4. If Weighted Allocation Type and there are existing reliability data values, these may be locked in prior to the reliability allocation.
5. Lock in any existing reliability data values that have been verified; reliability allocation will then allocate around those locked values.
6. Dependent on selected Weighting Type further weighting may be required to be defined.
7. Adjust weightings of model items, based on the selected Weighting Type.
8. Click 'Calculate' to run the Reliability Allocation analysis and produce results.
9. Review results of the analysis to determine if they are acceptable.
10. If results are not acceptable, create another analysis or return to the Overview/Management page, to edit the existing one.
11. Determine if any of the acceptable results are to be applied to model items within the project.
12. Select via the check boxes the acceptable results to be applied to the model items and then click 'Apply to System Model' to initiate the process.
13. Determine if any of the acceptable results are to be applied to an existing MCE.
14. Select via the check boxes the acceptable results to be applied to an existing MCE and then click 'Apply to MCE' to initiate the process.
15. Continue through the iterative process until all necessary reliability data values have been generated, reviewed and allocated.
16. Reliability Allocation conducted outputting target/allocated reliability metrics and a reliability allocation report.

Fields referenced in the diagram

• Create Reliability Allocation Analysis: Analysis Name, Analysis Description, Mission Profile, Target Item, Allocation Type, Weighting Type

Decision points

• Existing Reliability Data Values? — Yes → Lock Reliability Data Value(s); No → Define Weighting? decision.
• Define Weighting? — Yes → Adjust Weightings; No → Run Reliability Allocation Analysis.
• Results Acceptable? — No → loop back to Create Reliability Allocation Analysis; Yes → continue.
• Apply to System Model? — Yes → Apply Result(s) to System Model; No → Apply to MCE? decision.
• Apply to MCE? — Yes → Apply Result(s) to MCE; No → All Reliability Allocated? decision.
• All Reliability Allocated? — No → loop back to Create Reliability Allocation Analysis; Yes → Reliability Allocation Conducted.

Outputs

• Mean Time To Failure (MTTF): average time a model item will be in operations before failing.
• Reliability Allocation Report: contains all details and results of the report, including target reliability, duration of operations and maximum allowable failure rates.

Screenshot walkthrough (captions/labels extracted)

Step 1: Access Reliability Allocation Editor

• 'Analyses' menu: Fault Tree, Response Paths, Connection Matrix, Common Mode Analysis, Critical Item Analysis, Criticality & Reliability Editor, Diagnostic Analyses, Failure Rate Prediction, Markov Analysis, RBD Analysis, Reliability Allocation Editor (highlighted), Back-Fit RCM, Classic RCM, Maintenance Cost Estimates.
• "Reliability Allocation" tab "Overview/Management": empty "Reliability Allocation Analyses" table (Name/Target Item/Analysis Type/Target Require.../Type/Created) with add/open/duplicate/delete icon buttons. "Reliability Allocation Analysis Details" panel: Name, Description fields; "Reliability Allocation Target and Type" note "The Target Item and type of analysis are chosen when an analysis is created. These values cannot be changed once created." with Target Item, Allocation Type fields; "Mission Profile Definition" panel: Mission Profile dropdown, Duration, Mission Cycles, Σ Total, Description.

Step 2: Create Reliability Allocation Analysis

• "Create a new Allocation Analysis" dialogs, tabs Reliability Allocation / MTBUM / MTBCF / MTBF. Example 1: Name "Design Targets", Description "Reliability targets for Power Generation.", Target Item "Power Generation", Allocation Type "Equal" ("The reliability of items is allocated equally amongst the items in a level of indenture to satisfy the Target Reliability of the parent item. The calculations used depend on the type of RBD Group."). Mission Profile Definition: Mission Profile "New Group", Duration "91.194 hr (3.8 days)", Mission Cycles "N/A", Σ Total "7840.00 Kilometers".
• Example 2: Allocation Type "Weighted (AGREE)" with Weighting Type dropdown showing options State of the Art, Hardware Complexity, Functional Complexity (State of the Art selected, described: "developed item. Items with higher State of ... the Art are assigned relatively lower reliabilities than other items on the same level of indenture.") Mission Profile "Long Trip", Duration "5.211 hr (5.211 hours)", Mission Cycles "4.00", Σ Total "1792.00 Kilometers".
• Example 3: Allocation Type "Weighted (ARINC)" with Weighting Type "Historical Reliability Data" ("...based on the relative current MTTF values in the system model.").

Step 4: Set Target Reliability

• "Reliability Allocation" — "Analysis Configuration" tab: "Target Reliability" radio options 0.9999999 / 0.95 / 0.9 (selected) / Custom (0.9000000). "Target Item" panel (read-only): Target Item "Power Generation", Allocation Type "Equal". "Run Analysis": button "Calculate". "Requirements Verification Tool": "Create a Reliability Allocation requirement in the Requirement Verification Tool." Button "Export Requirement".

Step 5: Lock Reliability Value(s)

• "Analysis Configuration" for "Design Target 2": Target Reliability radio Custom = 0.8500000. Target Item "Diesel Engine", Allocation Type "Weighted (AGREE)", Weighting Type "Functional Complexity". "Weighted Analysis Inputs" table: Diesel Engine (Reliability 0.9998960, Functional Complexity 1.0*), Air Filter (0.9943798, N/A — locked via padlock icon), Coupling 1 (0.9999943, 1.0*), Engine (0.9999990, 1.0*), Injector Pump (0.9999984, 1.0*), Lift Pump (0.9999988, 1.0*), Primary Fuel Filter (0.9943798, 8.0), Secondary Fuel Filter (0.9943798, 8.0). Note: "* Indicates default value is being used." "Item Weighting" panel: Selected Item "Diesel Engine", Functional Complexity slider 1.0 (range 1.0–10.0) with guidance text: "Rank the item based on the Functional Complexity. A more complex item is given a higher ranking than a less complex item. Items with higher Functional Complexity are assigned relatively lower reliabilities on the same level of indenture."

Step 7: Adjust Weightings

• "Item Weighting" panel for Selected Item "Primary Fuel Filter": Functional Complexity slider set to 8.0 (range 1.0–10.0), same guidance text as Step 5.

Step 9: Review Analysis Results

• "Reliability Allocation" — "Analysis Result" tab for "Design Targets": buttons Select All, Deselect All, Apply to System Model, Apply to MCE. "Analysis Results" table columns Item, Allocated Reliability, Allocated Failure Rate (fpmh), Allocated MTTF (hrs), Duration (hrs). Rows: Power Generation (0.9, 80960.0547, 12.35, 1.30139) > Control Unit (0.9654893, 26986.6849, 37.06) > Diesel Engine (0.9654893, 26986.6849, 37.06) > K/N Redundancy Group (0.9930005, 5397.337, 185.28) > Air Filter/Primary Fuel Filter/Secondary Fuel Filter (0.9508866, 38697.4214, 25.84 each), Coupling 1/Engine/Injector Pump/Lift Pump (0.9930005, 5397.337, 185.28 each); Fuel Tank (0.9654893, 26986.6849, 37.06) > Inlet/Lining/Outlet (0.9883615, 8995.5616, 111.17 each).

Step 12: Apply Result(s) to System Model

• Same "Analysis Result" table with checkboxes selected (Select All checked) for Diesel Engine, K/N Redundancy Group, Air Filter, Primary Fuel Filter, Secondary Fuel Filter, Coupling 1, Engine, Injector Pump, Lift Pump.
• "Apply Reliability Allocation" — "Confirm Allocation" dialog: "Review the pending changes and select Finish to apply them. Note that any values outside the allowed range will be truncated to fit within the valid range." Table Name/Current MTTF/Allocated MTTF: Air Filter 1000000.00 → 25.84; Coupling 1 1000000.00 → 185.28; Engine 1000000.00 → 185.28; Injector Pump 1000000.00 → 185.28; Lift Pump 1000000.00 → 185.28; Primary Fuel Filter 1000000.00 → 25.84; Secondary Fuel Filter 1000000.00 → 25.84. Button: Finish, Cancel.

Step 14: Apply Result(s) to MCE

• Same results table, with "Apply to MCE" clicked. "Apply Reliability Allocation" wizard: first page "Confirm Allocation" listing Name "Training MCE" with Next/Finish/Cancel/Back buttons; second page "Confirm Allocation" table Name/Current MTTF/Allocated MTTF for Air Filter, Coupling 1, Diesel Engine, Engine, Injector Pump, Lift Pump, Power Generation, Primary Fuel Filter, Secondary Fuel Filter (each 1000000.00 → allocated value e.g. 25.84, 185.28, 37.06, 12.35).

Step 16: Reliability Allocation Conducted

• "Reliability Allocation Analysis" report: Name "Design Targets", Allocation Type "Weighted", Weighting Type "Hardware Complexity", Target Item "Vehicle System", Target Reliability "0.9500000"; "Mission Profile Definition": Name "Group of Trips", Duration of Operation "160 hr (6.668 days)", Cycles "1.00", Σ Total "7840.01 Kilometers", Description "Combination of the mission profiles Regular Trip and Long Trip, typical of the system." Table columns: Item, Failure Probability Distribution, Duration of Operation, Allocated Reliability, Maximum Allowable Failure Rate, Minimum Allowable MTTF, Weighting Factor, Characteristic Reliability, Characteristic Failure Rate, Characteristic MTTF — all rows using Exponential distribution, e.g. Vehicle System (149.12, 0.9500000, 343.98, 2907.15, 8.50, 0.0950074, 1220.0145, 77.96), Coupling (149.12, 0.9808812, 129.4548, 7724.7, 7.00, 0.9998509, 1.00, 999999.9), Driveline (148.94, 0.9863061, 92.5802, 10801.44, 5.00, 0.9922819, 439.6947, 17941.89), and further nested rows for Differential, Driveshaft, Parallel Group, Half Shaft Front/Rear, Planetary Gearbox Front/Rear, Wheel Front/Rear, Wheel Resistance Front/Rear, Transmission, Power Generation, Control Unit, Diesel Engine, Coupling 1, Engine, Injector Pump.

Related workflows

• WF11 – Create Mission Profiles (mission profile input)
• WF13 – Assign Reliability Values