RADC RELIABILITY ENGINEER'S TOOLKIT ?· RADC RELIABILITY ENGINEER'S TOOLKIT An application oriented…

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RADC RELIABILITY ENGINEER'S

TOOLKIT An application oriented

guide for the practicing reliability engineer

Systems Reliability and Engineering Division Rome Air Development Center

RADC RELIABILITY ENGINEER'S TOOLKIT

JULY 1988

An Application Oriented Guide for the

Practicing Reliability Engineer

Systems Reliability and Engineering Division Rome Air Development Center

Air Force Systems Command (AFSC) Griffiss Air Force Base, NY 13441-5700

QUICK REFERENCE

Quick Reference Application Index

H o w D c i L . . ?

Develop Quantitative Requirements

Reliability (R) 13

Maintainability (M)... 19

Testability(T)... 22

Tailor R&M Task Requirements 26

Develop a Contract Data Requirements List 28

Specify Information to Be Included in Proposals 30

Estimate Reliability Program Cost 31

Evaluate Contractor Proposals 33

Specify Part Stress Derating 41

Determine the Limitations of Common Cooling Techniques . 46

Understand Basic Parts Control 48

Identify Key R&M&T Topics for Evaluation at Design Reviews 53

Evaluate Contractor's Method of Managing Critical Items 59

Understand R&M&T Analysis Types and Purposes 63

Understand Reliability Prediction Methods 66

Understand Maintainability Prediction Methods 67

Understand Testability Analysis Methods 70

Evaluate a Reliability Prediction Report . 71

Evaluate Existing Reliability Data. 72

Evaluate a Maintainability/Testability Analysis Report 73

Evaluate a Failure Modes, Effects and Criticality Analyses

(FMECA) Report 74

Approximate the Reliability of Redundant Configurations 75

Perform a Quick (Parts Count) Reliability Prediction 79

Adjust Reliability Data for Different Conditions 91

Develop an Environmental Stress Screening (ESS) Program 97-100

Select a Reliability Qualification Test 102

Select a Maintainability Qualification Test 104

Select a Testability Demonstration Test 105

RADC RELIABILITY ENGINEER'S TOOLKIT 1

QUICK REFERENCE

Understand Key Points of a Failure Reporting and Corrective Action System (FRACAS) 106

Evaluate a Contractor's Failure Reporting System 107

Evaluate a Reliability Demonstration Test Plan .. 108

Evaluate a Reliability Demonstration Test Procedure 112

Evaluate a Maintainability Test Plan and Procedure . 113

Participate in R&M Testing 115

Evaluate R&M Demonstration Test Reports 116

For More Help AppendHces

How Do I... ?

Translate User Needs to R&M Requirements A-1

Develop SOW and Specification Requirements (Example) A-9

Understand the Basics of Warranties A-19

Develop Design Guidelines (Example) A-29

- Select a MIL-HDBK-781 Test Plan A-43

Calculate Confidence Intervals A-47

Calculate the Probability of Failure Occurrence A-52

Understand Reliability Growth Testing A-61

Select a MIL-STD-471 Test Plan A-69

Find More R&M Data A-75

- Obtain R&M Training A-83

Obtain R&M Periodicals A-89

Become Aware of R&M Symposia and Workshops A-90

Become Aware of R&M Specifications, Standards, Handbooks and RADC Technical Reports A-93

Know Who Air Force R&M Focal Points Are A-107

Understand Common Acronyms A-111

RADC RELIABILITY ENGINEER'S TOOLKIT

RADC RELIABILITY TOOLKIT 3

6 RADC RELIABILITY TOOLKIT 3

INTRODUCTION

This TOOLKIT is intended for use by a practicing reliability and maintainability (R&M) engineer. Emphasis is placed on his role in the various R&M activities of an electronic systems development program. The TOOLKIT is not intended to be a complete tutorial or technical treatment of the R&M discipline but rather a compendium of useful R&M reference information to be used in everyday practice.

The format of the TOOLKIT has been designed for easy reference. Five main sections are laid out to follow the normal time sequence of a

whicMTthe^uty^ an^^scritresThe R&M engineer's role in the key activities of that process. Because the processes (

s of certain steps in a particular process may be by reference to a

of the "how to" of the R&M engineer's activities have been the form of figures, tables, and step-by-step procedures as opposed to

of text. Appendices are included to give a greater depth of to some of the topics as well as to present additional useful

The TOOLKIT also includes a "Quick Reference Application Index" which can be I to quickly refer the R&M engineer to the portion of a section that.

z questions, A quicK reterence ror More Help Appendices index is\ included tor tne more in-deptn topics of tne appendices.

TOOLKIT 7

8 TOOLKIT

INTRODUCTION

The R&M 2000 process includes 21 Building Blocks as follows:

Source Selection

Allocation and Prediction Environmental Stress Q r r o o n i n n

Computer Aided Tools

These building blocks are derived from examining successful programs; they

This TOOLKIT, although not structured to address the R&M 2000 building blocks per se, addresses the practical application of proven reliability and maintainability techniques that results in meeting the R&M 2000 objectives.

RADC RELIABILITY TOOLKIT 9

Section R

How do I develop and specify the right RELIABILITY & MAINTAINABILITY requirements?

R&M Engineer's Role:

Develop Quantitative Requirements R1 Reliability 13

R2 Maintainability 19 R3 Testability 22

Develop R&M Task Requirements R4 Program Phase Terminology 24

R5 R&M Task Application/Priority 26

R6 Specify Contract Data Requirements 28

R7 Specify Information for Proposals 30

R8 Estimate Reliability Program Cost 31

S I Develop Proposal Evaluation Criteria 33

Appendix 2 Example R&M Program Tasks A-9

RADC RELIABILITY ENGINEER'S TOOLKIT 1 1

Requirement development is critical to program success. MlL-STDs CErsraot be blindly applied. Requirements must be taiSorod to the individual program situation considering the foiiowing:

Operation Environment

- Other Contract Provisions (incentives, warranties, etc.) Oft-The-Shelf Versus Neurly Designed Hardware

MIL-STD-470 MIL-STD-721 MIL-STD-785

MIL-STD-2165

DOD 5010.12-L

AFR 800-2 AFR 800-18 RADC-TR-87-50

"Maintainability Program for Systems and Equipment" "Definition of Terms for Reliability and Maintainability" "Reliability Program for Systems and Equipment Development and Production"

"Testability Programs for Electronic Systems and Equipment" "Acquisition Management Systems and Data Requirements Control List" (complete Data Item Description listing)

"Acquisition Program Management" "Air Force Reliability and Maintainability Program" "R&M Program Cost Drivers"

"RADC Program Managers Guide to Reliability and Maintainability" Slide Rule (order directly from RADC/RBE, Griffiss AFB NY 13441-5700)

12 RADC RELIABILITY ENGINEER'S TOOLKIT

REQUIREMENTSTOPIC R1

Topic R1 Quantitative Reliability Requirements Scope of Requirements: Reliability parameters expressed by operational users and ones specified in contractual documents take many forms. Tables R1 -1 and R1 -2 identify the characteristics of reliability parameters.

Table R1-1: Logistics (Basic) and Mission Reliability Characteristics

Logistics (Basic) Reliability Mission Reliability

Measure of system's ability to operate without logistics support.

Recognize effects of all occurrences that demand support without regard to effect on mission.

Degraded by redundancy.

Usually equal to or lower than mission reliability.

Measure of system's ability to complete mission.

Consider only failures that cause mission abort.

Improved by redundancy.

Usually higher than logistics reliability.

Table R1-2: Operational and Contractual Reliability Characteristics

Contractual Reliability

Used to define, measure and evaluate contractor's program.

Derived from operational needs. Selected such that achieving them

allows projected satisfaction of operational reliability.

Expressed in inherent values.

Account only for failure events subject to contractor control.

Include only design and manufacturing characteristics.

Operational Reliability

Used to describe reliability performance when operated in planned environment.

Not used for contract reliability requirements (requires translation).

Used to describe needed level of reliability performance.

Include combined effects of item design, quality, installation environment, maintenance policy, repair, etc.

RADC RELIABILITY ENGINEER'S TOOLKIT 13

REQUIREMENTSTOPIC R1

Table R1-2 (continued)

Contractual Reliability

Typical terms: MTBF (mean-time-between-faili

Mission MTBF (sometimes also called MTBCF)

Operational Reliability

Typical terms: MTBM (mean-time-between-

maintenance)

MTBD (mean-time-between-demand)

MTBR (mean-time-between-removal)

MTBCF (mean-time-between-critical-failure)

Operational