Reliability, Reliability Growth, and Total Ownership Costs

Stacie Taylor andBrent Russell

Reliability—Why It Matters

2

Reliability—Why It Matters

3

Reliability—Why It Matters

4

• Air Force cost example:‒ C-17: Wing tip light bulb to illuminate forward and aft edges‒ Estimate average life

• KC-135 Mean Time Between Failure = 645 hours• C-17 Mean Time Between Failure = 25 hours (forward) and 50

hours (aft)

‒ $4.5M life cycle cost impact for maintenance labor, parts, and delay time

Acquisition costs are small % of life cycle cost

5

Life Cycle Costs – Spending

R&D

Production

10% 30%60%

Operations&

Support

Milestones A B C

6

Life Cycle Costs – Commitment

R&D

Production

Operations&

Support

Milestones A B C

0.7

0.850.95 0.99

1

Design & testing influence 70%-85% of the life cycle cost

Does It Really Cost Substantially More to Design Reliability into a System?

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Source: DOT&E Brief 2010

* 0 failures in one year

Does It Really Cost Substantially More to Design Reliability into a System?

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Source: DOT&E Brief 2010

* 0 failures in one year

Does It Really Cost Substantially More to Design Reliability into a System?

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Source: DOT&E Brief 2010

* 0 failures in one year

Reliability Growth’s Impact on Total Ownership Cost

10

Costs in FY 2008 $M

80

114

175

215 220

CAP = Corrective Action PeriodDT = Developmental TestLUT = Limited User TestIOT = Initial Operational Test

$869

149

$894

$1,103

$1,701

$2,457

Reliability and Total Ownership Cost

11

Example trade space– Reliability– Maintenance concept– Availability– Spares pipeline costs– Failure diagnostic

capability– System use rates– System funding

profiles

R&D/Acq/O&SLowest $$

Higher $$ (increased R&D/Production Cost)

Higher $$ (increased O&S Cost)

Total Ownership Cost

Reliability and Total Ownership Cost

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R&D/Acq/O&SLowest $$

Higher $$ (increased R&D/Production Cost)

Higher $$ (increased O&S Cost)

Total Ownership Cost

Recent Logistics Management Institute study concludes that:

30%-60% reductionin support cost is

achievable through attention to reliability

in the design

Reliability Growth’s Impact on Total Ownership Cost

13

Costs in FY 2008 $M

80

114

175

215 220

CAP = Corrective Action PeriodDT = Developmental TestLUT = Limited User TestIOT = Initial Operational Test

$869

149

$894

$1,103

$1,701

$2,457

Definition - Reliability

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• Technical: Reliability is the probability that an item (component or system) will perform its intended function for a specified period of timewhen operated in its design environment.

• Succinct: Reliability is quality over time.

Definition – Reliability Growth

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• Reliability Growth: The positive improvement in a reliability parameter over a period of time due to changes in the product design or manufacturing process (MIL-HDBK 189C, 2011).

• Three primary phases: Planning, Tracking, and Projection

MS=Milestone P&D=Production & DeploymentTD=Technology Development FRP=Full Rate ProductionEMD=Engineering & Manufacturing Development

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2005 DOD Guide for Achieving RAM

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2005 DOD Guide for Achieving RAM

Step 2: Design and redesign for RAM

Step 4: Monitor field performance and sustain reliability

Operations & Support

Step 1: Understand and communicate user needs and constraints

Step 3: Produce reliable and maintainable systems

Reliability Objectives

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Two Approaches to Achieve Reliability

19Source: Key Issues in Reliability Growth, Dr Gilmore (DOT&E) brief to National Academy of Sciences 22 Sep 11

Design for Reliability Reliability Growth Methods

Definition – Reliability Growth Management

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• Reliability Growth Management: The systematic planning for reliability achievement as a function of time and other resources, and controlling the ongoing rate of achievement by reallocation of resources based on comparisons between planned and achieved reliability values (MIL-HDBK 189C, 2011)

Reliability Objectives

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Reliability Growth Process Overview

22 Source: AMSAA Reliability Growth Short Course, 2010

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Reliability Growth Planning - Goals

Cost

PerformanceSchedule

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RG Planning Goals Address Critical Processes

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RG Planning Goals Address Critical Processes

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0

50

100

150

200

250

300

350

MT

BF

Test Time (hours)

Hard Target Concept - Reliability Growth Planning Curve

Idealized Curve TD Captive 1 TD Captive 2 OA Captive EMD Captive 1 EMD Captive 2 EMD Captive 3 IOT

Requirement

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Reliability Growth Tracking - Goals

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Reliability Growth Projection - Goals

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Reliability Growth Projection - Goals

Management Strategy

A-mode

B-mode

A-mode

B-mode

B-mode

B-mode

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Reliability Growth Projection - Goals

Management Strategy

A-mode

B-mode

A-mode

B-mode

B-mode

B-mode

• Corrective Actions • Fix Effectiveness

Estimation of reliability at end of next test phase

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RG – Estimate

Every single part of RG depends on the

initial reliability

Predicting Initial Reliability

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• Common prediction method‒ Standards-based methods

‒ MIL-HDBK 217 (electronic)‒ Telecordia SR-332 (electronic)‒ Siemens SN 29500 (electronic and electromechanical)‒ FIDES (electronic)‒ NSWC 11 (mechanical)

Handbook-Based Reliability Predictions Versus Actual Measured MTBF

33 Source: Reliability Predictions: A Continued Reliance on a Failed Approach, Dais et al, 2013

Predicting Initial Reliability (cont)

Predicting Initial Reliability (cont)

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• Better prediction methods‒ Field data

‒ Physics of failure

Predicting Initial Reliability (cont)

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• Better prediction methods‒ System reliability models

‒ Reliability Block Diagrams‒ Fault Tree Analysis

failure

to stop

fluid system

failuremechanical

brake failure

wheel system

failurerear pad

failure

and

M C

and

or or

and

BP3 BP4or

right rear

wheel failure

WC4 BP4

or

left front

wheel failure

WC1 BP1

right

front

left

rear.

.

.

.

36

Relationship within RAM and TOC

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Questions?