DI-SESS-81496B

Reliability and Maintainability (R&M) Block Diagrams and Mathematical Models Report

Documents the R&M block diagrams and mathematical models data used to support reliability and maintainability allocations, predictions, assessments, design analyses, and trade-offs for configuration items of the work breakdown structure.

Approval DateOctober 8, 2019

AMSC NumberN10109

Preparing ActivityAS

Project NumberSESS-2019-060

OPR—

DTIC ApplicableYes

GIDEP ApplicableYes

LimitationNo

Applicable Forms—

Approval Limitation—

Form Version—

DID Formatfree_text

963C CompliantYes

DISTRIBUTION STATEMENT A: Approved for public release; distribution is unlimited.

Supersedes

DI-RELI-81496A

—

Description & Purpose

—

Application & Interrelationship

—

Use & Relationship

The Reliability and Maintainability (R&M) Block Diagrams and Mathematical Models Report documents the data used to support R&M allocations, predictions, assessments, design analyses, and trade-offs associated with configuration items of the work breakdown structure.

This Data Item Description (DID) contains the format, content, and intended use information for the data deliverable resulting from the work task described in the contract.

This DID should be tailored appropriately.

This DID supersedes DI-RELI-81496A.

Preparation Instructions

1Reference DocumentsNone.

2FormatThe R&M block diagrams and mathematical models report shall be in the contractor's format.

3ContentThe report shall include the R&M block diagrams and mathematical models and supplementary information suitable for allocation, prediction, assessment, and Failure Mode, Effects, and Criticality Analysis (FMECA) analysis related to the configuration items (including software configuration items) of the system's work breakdown structure. The R&M block diagrams and math models shall be developed to the level required and contain the detail required to support these analyses, in order to avoid duplication of effort across analyses. The report shall include:

3.1The type of reliability modelThe type of reliability model (mission or logistics) and the modeling method.

3.2The type of functional level maintainability block diagramThe type of functional level maintainability block diagram depicting the levels at which the repair can be made.

3.3A reference designation listA reference designation list when warranted by system complexity. The list shall be provided when block diagrams include elements, which require correlation between block diagram reference numbers, work breakdown structure identification, or location of specific elements on a diagram set or diagram sheet. The list shall be a composite cross-reference and item element locator (both by name and by designation).

3.4An excluded equipment listAn excluded equipment list, which describes system elements not shown on the block diagram. Rationale for each exclusion shall be provided.

3.5Identification of the technical assumptions usedIdentification of the technical assumptions used, including:

3.5.1Service use profile, mission profile, environmental profile

3.5.2Operational and maintenance concepts and requirements

3.5.3Levels to which fault detection and fault isolation is to be extended

3.5.4Redundancy, alternate modes of degraded operation

3.5.5Tradeoff considerations

3.5.6Human interface and software

3.6R&M block diagramsR&M block diagrams that:

3.6.1Represent the system specificationRepresent the system specification and are segmented to represent variables such as: mission type, mission phase, functional mode(s) of operation, duty cycle, maintenance concept, or other factors. When information is limited in the early phase of item development, functional level block diagrams shall be constructed. Diagrams constructed at this level shall contain blocks representing the lowest identifiable function consistent with item element definition (name and designation).

3.6.2Include and identify blocks representing Government Furnished EquipmentInclude and identify blocks representing Government Furnished Equipment (GFE), Non-Developmental Items (NDI), and Commercial Off The Shelf (COTS) items. Information shall be included to reflect the use of designated GFE, NDI, and COTS into the design.

3.6.3Are partitioned to agree with the work breakdown structureAre partitioned to agree with the work breakdown structure. Partitioning shall provide diagrams for each configuration item subdivision, which reflect and emphasize interfaces with the next lower level of the breakdown structure. In this manner, the block diagram consists of a series of models which are logically derived and capable of being combined to any level of complexity (Sample provided as Figure 1).

3.6.4Indicate interfaces both external to the physical boundary of the item and internal to the itemIndicate interfaces both external to the physical boundary of the item and internal to the item. Particular attention should be paid to interfaces of functional significance including GFE, NDI, and COTS. Interfaces shall be consistent with end item specification, intended purpose, mission use, or higher order functions when the item is used in conjunction with other items.

3.6.5Identify critical items in the system design

3.6.6Identify in maintainability diagramsIdentify in maintainability diagrams, which elements are to be designed as repairable or replaceable items for maintainability enhancement. In addition, BIT design expectations (e.g. fault detection, fault isolation), along with test equipment needs for on-line and off-line testing, shall be indicated. (Sample provided as Figure 2).

3.7Configurations identified during redundancy studies, allocations, or tradeoff studiesConfigurations identified during redundancy studies, allocations, or tradeoff studies related to item reliability improvement. Reliability problems leading to the inclusion of redundant elements shall be identified. Additional information describing redundancy considerations not obvious from the block diagrams shall be included. Typical redundancy considerations include:

3.7.1Level (e.g., subsystem, part)

3.7.2Type (e.g., active, standby, M out of N)

3.7.3Element monitoring (e.g., continuous, interval monitored)

3.7.4Rationale (e.g., repair without downtime, prolong operating life)

3.7.5Alternatives with/without redundancy

3.7.6Elements, which can be checked

3.7.7Elements, which can be inspected

3.7.8Elements whose failure stresses alternate path elements

3.7.9Elements whose failure degrades performance

3.8Mathematical modelsMathematical models that:

3.8.1Include technical assumptions necessary for model interpretationInclude technical assumptions necessary for model interpretation, model completeness, and model clarity. Assumptions shall be consistent with the phase of item definition, such as frequency distributions (failure rate, time to repair), mathematical approximations, statistical techniques, single mode/multimodal failure, wear out factors/characteristics, failure independency, and operating time.

3.8.2Represent the system specification the level of detailsRepresent the system specification the level of details, and be organized consistent with the R&M block diagrams. Charts, tables, or other methods may be used to indicate which equation, model, or sets of models apply to specific mission(s) or other variables. The method used shall be the same used for block diagrams, and may include provisions for both the diagram and mathematical model.

3.8.3Supplementary information necessary for proper understanding and use of the modelSupplementary information necessary for proper understanding and use of the model shall be included when specific method(s) of mathematics employed extend beyond the basic rules, practices, and procedures of reliability mathematics (e.g., rules of Boolean algebra, classical laws of reliability, etc.).

3.9Conclusions and recommendations based upon the data developedConclusions and recommendations based upon the data developed. Interpretation and comments concerning diagrams, models, and courses of action to resolve R&M problems shall be included. Consideration should be given to data deficiencies, Government Furnished Equipment (GFE) problems, tradeoffs, assumptions, risks, interpretations affecting R&M planning, qualitative or quantitative information affecting the program, and other pertinent factors related to the diagrams or models.

References

—

Figures

Figure 1. Sample Figure 1. Block Diagram Model Partitioning

Figure 2. Sample Figure 2. Functional Level Maintainability Diagram

Schema v3.0Community-maintained · Verify against ASSIST

Community-maintained — not an official government database.
Verify against ASSIST·GitHub·About·Disclaimer