structural prognostics and health management (sphm) for

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F-35 Program Information

Non Export Controlled Information – Releasable to Foreign Persons

© 2009 Lockheed Martin Corporation

Structural Prognostics and Health Management (SPHM)

for the F-35 Lightning II

Michael R. Woodward

Principal EngineerF-35 Chief Engineer’s Office

Lockheed Martin Aeronautics Company

2009 Aircraft Structural Integrity Program (ASIP) Conference

December 1-3, 2009

Jacksonville, FL

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

Robert J. Burt

DirectorF-35 Structures Development


JC (Carl) McConnell

Senior Staff EngineerF-35 Structures Development


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Public Information Release Authorization AER200911001

UK(138 STOVL)

United States - 2443

Italy

(131)

Netherlands(85)

Turkey(100)

Canada(80)

Australia(100)

Norway

(56)

Denmark(48)

Potential FMS Customers

Scope – F-35 Users

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F-35 SPHM Effort Supports 3 Aircraft Types

F-35C CV

Span . . . . . . . . . . . . . . . . . . . . . . . . 43 ft / 13.11 m

Length . . . . . . . . . . . . . . . . . . . . . 51.4 ft / 15.67 m

Wing area . . . . . . . . . . . . . . . . . . 668 ft2 / 62.06 m2

Combat radius (internal fuel) >600 n.mi / 1,111 km

Range (internal fuel) . . . . . >1,200 n.mi / 2,222 km

F-35B STOVL

Span . . . . . . . . . . . . . . . . . . . . . . . 35 ft / 10.67 m

Length . . . . . . . . . . . . . . . . . . . . 51.2 ft / 15.61 m

Wing area . . . . . . . . . . . . . . . . . . 460 ft2 / 42.7 m2

Combat radius (internal fuel) >450 n.mi / 833 km

Range (internal fuel) . . . . . . ~900 n.mi / 1,667 km

F-35A CTOL

Span . . . . . . . . . . . . . . . . . . . . . . . . 35 ft / 10.67 m

Length . . . . . . . . . . . . . . . . . . . . . 51.4 ft / 15.67 m

Wing area . . . . . . . . . . . . . . . . . . 460 ft2 / 42.7 m2

Combat radius (internal fuel) >590 n.mi / 1,093 km

Range (internal fuel) . . . . . ~1,200 n.mi / 2,222 km

Convention

Take-

Off and

Landing

Short

Take-

Off and

Vertical

Landing

Carrier

Variant

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F-35 SPHM Data

Collection/Processing/Assessment

• Deployment Scenarios

– USAF/USN/USMC

• Continental US

• Carrier Deployment

• Austere Forward Deployment

• Foreign Base Deployment

– Non-US Users (Partners/FMS)

• Data Collection/Processing/ Assessment Scenarios

– US Users

• JSF Program Task

• US Service Task

– Non-US Users (Partners/FMS)

• JSF Program Task

• Sovereign Task

SPHM Data

Collection/Processing/Assessment

F-35 SPHM Data Collection/Processing/Assessment Architecture

Accommodates Diverse Deployment Scenarios

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F-35 ASIP Status

Interpretation and

Evaluation of Test

Results

Durability AnalysisSelection of Materials

Climatic TestsDamage Tolerance AnalysisNondestructive Inspection

Program

Force Management UpdatesIndividual Aircraft Tracking

(IAT) Program Development

Damage Tolerance

Tests

Stress AnalysisCorrosion Prevention &

Control Program (CPCP)

Aircraft Structural RecordsLoads/ Environment Spectra

Survey (L/ESS) Development

Durability TestsDesign Chemical/Thermal

Environment Spectra

Durability & Damage

Tolerance Control

Program

ASIP ManualForce Structural

Maintenance Plan (FSMP)

Flight TestsDesign Service Loads

Spectra

Structural Design Criteria

Loads/Environment Spectra

Survey (L/ESS)

Strength Summary &

Operating Restrictions

(SSOR)

First Flight

Verification Ground

Tests

Loads AnalysisDesign Service Life &

Design Usage

Individual Aircraft Tracking

(IAT) Program

Certification AnalysesStatic TestMaterial and Joint

Allowable Testing

ASIP Master Plan

Force Management

Execution

Certification & Force

Management

Development

Full Scale

Testing

Design Analysis &

Development Testing

Design Information

Task VTask IVTask IIITask IITask I

Complete In Work Planned

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T

T/2

t/2

tAssumed Initial

Design Flaw

Assumed In-service

Inspectable Flaw

(Time to critical flaw length)

Critical flaw size

Initial inspection time

Maintenance Action Flaw Size

(Initial Inspection)

Maintenance Action

Flaw(2)

Mandatory Repair

Flaw(1)

(Reinspection Interval)

Flight Hours

Flaw Size

Notes:

1. Mandatory Repair Flaw: Largest flaw

size allowed by the structural part before

a maintenance action is required for

repair.

2. Maintenance Action Flaw size

(reinspection) is not always equal to

mandatory repair flaw size as shown in

this figure.CTOL Fracture Critical Inspections

T

T/2

t/2

tAssumed Initial

Design Flaw

Assumed In-service

Inspectable Flaw

(Time to critical flaw length)

Critical flaw size


Maintenance Action Flaw Size

(Initial Inspection)

Maintenance Action

Flaw(2)

Mandatory Repair

Flaw(1)


Flight Hours

Flaw Size

Notes:

1. Mandatory Repair Flaw: Largest flaw

size allowed by the structural part before

a maintenance action is required for

repair.

2. Maintenance Action Flaw size

(reinspection) is not always equal to

mandatory repair flaw size as shown in

this figure.CTOL Fracture Critical Inspections

T

T/2

t/2

t

Assumed In-service

Inspectable Flaw

(Unfactored Time to crack intiation)

Critical flaw size



Flight Hours

Flaw Size

STOVL & CV Maintenance Critical & Normal Controls Inspections

T

T/2

t/2

t

Assumed In-service

Inspectable Flaw

(Unfactored Time to crack intiation)

Critical flaw size



Flight Hours

Flaw Size

STOVL & CV Maintenance Critical & Normal Controls Inspections

F-35 Structural Health Management

Strategies

• Designed to Support

Various Damage

Accumulation and

Management

Approaches

– Crack Growth and

Crack Initiation at

Specified Control

Points

– Flight Parameter-

based Load

Equations

– PHM Sensor-based

Load and Stress

Equations

F-35 SPHM Strategy Accommodates All User Approaches

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F-35 PHM Architecture

Air Vehicle On-Board

Health Assessment

Air Vehicle/Support System

Interface

ALGS &

Off-Board PHM

• SPHM Processing:− L/ESS− IAT− Conditional Events

• Generate Reports• Store/DistributePHM Information

• Determine Maintenance Requirements

Mission Critical

PHM Data

Displays and Controls

.

Portable Maintenance

Aid (PMA)

Flight Critical

PHM Area

Managers

PVI

TO Data,

Status, Consumables, Stores

Off-Board Diagnostics

Health/Service Info

Database

AV PHM

Area Manager

Fault

Accommodation

Status via

ICAWS

Portable Memory Device

(PMD)

Propulsion

Mission

Systems

Structures

Vehicle

Systems

Crash Data

RecorderNVM

Maintenance

Vehicle

Interface

• Fleet Decision Support

•Maintenance Planning

Products:

Structural PHM Data/Information

Activities:

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Elements of F-35 SPHM

• Loads/Environment Spectra Survey (L/ESS)

– Monitoring Actual A/C Usage

– Comparing Actual A/C Usage to Baseline Usage

– Generating Updated Baseline Usage Spectra and Environments

• Individual Aircraft Tracking

– Determination of Individual A/C Damage for Actual Usage vs. Baseline

Usage

• Conditional Event Reporting and Analysis

– Conditional Event Reporting

• On-board Detection and Reporting of Structural Overloads

– For Example –Wing Root Bending Moment/Shear

– Conditional Event Analysis

• Off-board Confirmation and Refinement of Conditional Event

• Mapping of Conditional Event Maintenance Tasks Based to Event

Type(s) and Magnitude(s)

F-35 SPHM System Supports ASIP Task V

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F-35 SPHM ConOps/Tempo

AVPHM System - On A/C

On A/C Data

- Maneuver Time History

- Discrete Parameter Time

History

- SPHM Gage Data

- Conditional Event Data

- Configuration Data

...

PMD Cartridge

Process Data

- L/ESS

- IAT

- Conditional Event

Define Maintenance

- Conditional Event

- Per FSMP

Transfer data to ALIS

Ground Station – Unit Level

•Ground Station Data

Synchronized with

Accumulated Data on ALIS

•Generate/Distribute Fleet

Usage Reports

•Reprocess Data if Required

•Raw A/C Data

Transferred to Data

Warehouse

ALIS

SME Review

- L/ESS Assessment

- IAT Assessment

- FSMP Update

- IAT Update

-Fleet Management

Recommendations

Data Warehouse

Long Term Storage

of Raw A/C Data

Daily Weekly

Data >5 Years Old

3-6 Months

Fleet Management

Update

-Usage Update

-Life Update

Initial - 8000 FH

Updates ~ 5 Y

ConOps/Tempo Consistent with Traditional ASIP Practice

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F-35 L/ESS – Usage Data Recording

• Over 150 Parameter Time Histories Captured

– Strain Gauge Data

– Accelerations (Rotational & Translational)

– Velocities & Rates (Rotational & Translational)

– Air Data System Parameters (AOA, Mach No., Altitude, etc)

– Control Surface Deflections

– Stores Configurations & Masses

– Fuel Tank States

– Engine Parameters

– Miscellaneous Discrete Parameters (Weight-on-Wheels,

Door Positions, etc)

Unprecedented Aircraft Usage Data Capture

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• Evaluated Data Reported

– Peak-Valley Tables

– From-To Tables

– Exceedence Curves

– Range Pair Tables

– A/C Sortie Data

– Control surface position changes (All Surfaces)

– Nz and NzW

– Bending Moments (Fuselage, Wing Root, Wing

Mid-Span, Horizontal Tail and Vertical Tail)

– Time at Mach-Altitude-Weight

– Time in qbar-AOA ranges

– Takeoff and Landing Gross Weight Bands

– On Ground Nz

• Redundant On-board Storage Assures

Sufficient Data Capture in Event of Data

Download Failure

F-35 L/ESS Evaluation

F-35 L/ESS Supports ASIP Task V with High Quality Data

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F-35 IAT Approach

• External Loads Sources– A/C State Parameters are used to calculate Airframe Maneuver Loads, Landing Loads, Taxi, Take-Off and other Ground Handling Loads

• Utilizes same Load Relationships as in L/ESS

– Direct Measurement – SPHM Sensors

• Stress– Algorithms calculate Stress as a Function of External Load for Individual Control Points

– Algorithms Developed using Appropriate Regression Techniques

• Accounts for Flight Control Law related discontinuities via piecewise continuity

• Damage– Calculated for Critical Structural Details and Generic Algorithms Sensitive to Individual External Loads

– Calculations are Consistent with Variant Specific Design Criteria

• Crack Growth

• Crack Initiation

F-35 IAT Program Encompasses All Services Tracking Methods

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F-35 IAT Control Point Selection and

Verification

• Initial F-35 SDD IAT Control Point List

– Locations Distributed to Capture Major Load Parameters

– Locations in Critical Load Paths

– Low Margin/Limited Life Locations

– Locations to Capture Discrete Load Sources

• Updated Following completion of Full-scale Ground and Flight Tests

– Result of Final Certification Analysis – Updated Loads

– Result of Test Findings

• IAT Algorithm Verification

– Regression Accuracy:

• Maximum Dependent Variable Error

• Correlation Coefficient

– Damage Calculation Accuracy:

• Design Baseline Life versus IAT Algorithm Based Life (Using Design Spectrum Endpoints)

• Design Baseline Life versus IAT Algorithm Based Life (Using Simulated A/C Parameter Time Histories)

• The Performance of IAT Models will be Monitored throughout the Life of the Program

• Problems will be Identified and Corrected as Necessary

F-35 Control Point List Supports Task V Activities

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F-35 IAT – SPHM Sensors

• Load Source Monitored

• All Variants – Center Fuselage Bending, Wing Root Bending/Shear, Vertical Tail Bending/Shear, Horizontal Tail Bending, Flaperon Bending, Forward Fuselage Bending, Aft Fuselage Bending

• CV – Launch Bar Axial, Wingfold Shear

• SPHM Sensors Data Acquisition Rate Sufficient to Detect Dynamic

Response

• Present on All A/C

Rear Spar Outboard Flaperon Hinge – LH

Fwd Fuse Bending (Upper Sill Longeron)

Center Fuse Bending (Lower Keel Longeron)

LH VT Shear Attachment

LH HT Actuator Lug

LH Aft Fuse Kicked Keel

LH VT Bending Attachment

Wing Root BH 496 - LH

Wing Root – LH Shear

Wing Root – LH Bending

Rear Spar Outboard Flaperon Hinge – LH

Fwd Fuse Bending (Upper Sill Longeron)

Center Fuse Bending (Lower Keel Longeron)

LH VT Shear Attachment

LH HT Actuator Lug

LH Aft Fuse Kicked Keel

LH VT Bending Attachment

Wing Root BH 496 - LH

Wing Root – LH Shear

Wing Root – LH Bending

Wingfold Joint

Leading Edge - Shear

Wingfold Joint

Trailing Edge - Shear

Launch Bar Attach

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F-35 IAT Output Reporting

• Download Summary

• Aircraft Sortie Usage

Summary

• Tracking Model Performance

Summary

• Individual Aircraft Control

Point IAT Summaries

• Fleet Comparisons

• Control Point Exceedance

Data

• Tracking Model Performance

and Status Data

• Maintenance Action Update

Periodic Updates of FSMP Provide Data for

Force Management Recommendations

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F-35 Conditional Event Reporting

• Determine Structural Overloads On A/C Due to:

– Flight Maneuver

– Hard Landings

– Over-Speed Events

• Compare Measured Loads Against Allowable Envelopes

– Determine the load at specific locations on the airframe by consideration of aero, inertia and stores inertia loads

– Locations driven by unique loading environments

• Generate Health Report Code Unique to Event Type

FS270 Vertical

Bending Moment

Bending Moment and

Torsion and Torsion

Horizontal Tail

Bending Moment and

Torsion

Bending Moment and

Torsion

Vertical

Bending Moment

Wing Root CV Wing Fold

Vertical Tail

Wing Bending Moment

CER Notifies Users of the Event

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F-35 Conditional Event Analysis

• CEA is the Off-board Assessment/Verification of CER

– CEA more Rigorous than CER

• Able to Localize Overload to Specific Structure

• Assessment of A/C Data Quality e.g. Did Overload

Occur Because of A/C Parameter Noise?

• CEA Initiation

– Upon HRC resulting from On-board Detection of a

Conditional Event

– Pilot Reported Event

• Determines Level of Severity

• Determines Maintenance Tasks based on Location and

Level of Severity

CEA Assures Appropriate Level of Maintenance is Performed

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F-35 Conditional Event Maintenance

• Conditional Event Maintenance Encompasses

Maintenance/Inspection Tasks Required to Clear A/C for Flight

Following a Conditional Event

• Three Levels Defined

– Level 1 – Visual Inspection + Some NDI

– Level 2 – Level 1 + Additional Visual Inspection/NDI

– Level 3 – Level 2 + Ground A/C, Generate Action Request to

Have Subject Matter Expert Review/Resolution of Event

• Conditional Event Maintenance Generation

– Conditional Event Report – Engineering Source Data

– Maintenance Task Analysis

– Electronic Tech Data Implemented within ALIS

Required Maintenance a Function of Event and Event Magnitude

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F-35 Task IV and V ASIP Activities

2009 2012 2013 2014 2015 2016 2017 201920182010 2011Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1 Q2 Q3 Q4Q1

1st Production A/C Deliveries

Flight TestSTOVL

CTOLCV

Program Milestones

OT&E

USMC IOC USAF IOC USN IOC

Durability TestSTOVL

CTOL

CV

Initial L/ESS

Initial IAT

Task IV ASIP ActivitiesInitial CER/CEA/CEM

L/ESS Update

IAT Update

CER/CEA/CEM Update

ALIS 2.0

Complete

ALIS 2.0

Deployed

Initial FSMPs FSMP Updates

Task V ASIP Activities

SPHM Data Processing

IAT/L/ESS/CER/CEA Status Reports

CTOL

19k FHCTOL Full Clear.

CTOL

82k FH

CTOL

223k FH

Initial Usage Updates (All Variants) Next Usage

Update 2022

AF-6 BF-6 CF-5

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Summary

• F-35 SPHM Effort is Global in Nature

• System and Computational Architecture Designed for

Flexibility in Order to Meet the Fleet Management

Requirements of All Customers

• F-35 SPHM System Characterized By

– Distributed Processing to Address Varied A/C

Deployment Scenarios

– High Degree of Automation

–On-board and Off-board Computational Capability

Increase Data Availability and Quality

F-35 SPHM Provides the Right Data for ASIP Fleet

Managers World-wide

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structural prognostics and health management (sphm) for

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