1

David WhiteAvion Inc.

Huntsville, Alabama

David WhiteAvion Inc.

Huntsville, Alabama

Requirements for Life Cycle Management of U.S. Army Helicopter

Structural Integrity

Requirements for Life Cycle Management of U.S. Army Helicopter

Structural Integrity

2007 USAF ASIP Conference04-06 December 2007 Palm Springs, California2007 USAF ASIP Conference04-06 December 2007 Palm Springs, California

450 Cargo

Number & Mission

CH-47 Chinook

Aircraft

46+ years1961

Design Age

Entered Service

450 Cargo

Number & Mission

CH-47 Chinook

Aircraft

46+ years1961

Design Age

Entered Service

1600 Utility

450 Cargo

Number & Mission

UH-60 Black Hawk

CH-47 Chinook

Aircraft

29+ years1978

46+ years1961

Design Age

Entered Service

1600 Utility

450 Cargo

Number & Mission

UH-60 Black Hawk

CH-47 Chinook

Aircraft

29+ years1978

46+ years1961

Design Age

Entered Service

700 Attack

1600 Utility

450 Cargo

Number & Mission

AH-64 Apache

UH-60 Black Hawk

CH-47 Chinook

Aircraft

23+ years1984

29+ years1978

46+ years1961

Design Age

Entered Service

700 Attack

1600 Utility

450 Cargo

Number & Mission

AH-64 Apache

UH-60 Black Hawk

CH-47 Chinook

Aircraft

23+ years1984

29+ years1978

46+ years1961

Design Age

Entered Service

► Average design age ~30 years. ► 2000 of these 2750 helicopters will be upgraded

to remain in service beyond 2030.

US Army Frontline Combat Helicopters are at Mid LifeUS Army Frontline Combat Helicopters are at Mid Life

2

Operational Usage Severity Has Increased DramaticallyOperational Usage Severity Has Increased Dramatically

► High Altitude► Desert Sand

Army helicopters must remain available, safe, and affordable... ► while flying combat OPTEMPO of 3-4x peacetime...► in increasingly harsh environments.

► Ship Operations► Salt Environment

► Combat Maneuvers► Expanded Envelope

3

Components Fall Short of Design Life ExpectationsComponents Fall Short of Design Life Expectations

100%, $50M

Design Life

Based upon 96 AH-64A/D, CH-47D/F, UH-60A/L Component Part Nos.

$00% 50% 100% 150% 200% 250% 300%

% Design Life

$50

$100

$150

$200

$300

Cos

t per

Yea

r -M

illio

ns

$250

BALLPARK PARTS and LABOR COST:Assumption: All components will achieve the service life of those in maintenance database (peacetime usage).

Remediation

Δ=$150M

25%, $200M

Typical US Army Actuals

250%, $20M

Monitored Life

Δ=$30M

Life Extension33%, $150M

Δ=$50M Near Term Objective

4

► Redesign► Rework

ImproveComponent

ContinueUsage

Discard Component

Inspect ConditionInspect

Condition► Material Condition► Degradation Trends

Predict RemovalPredict

Removal► Usage Correlation► Maintenance Actions► Remaining Useful Life

Monitor Usage

Monitor Usage

► Flight Parameters► Duty Cycles► Flight Regimes

Monitor Loads

Monitor Loads

► Flight Load Survey Data► Statistical Correlations► Monitor Loads/Sequences

Component Life Cycle Management ProcessComponent Life Cycle Management Process

Monitor Strain

Monitor Strain

► Digital Optical Correlation► Zero Load Strain► Material Deformation

5

Structural ConditionMonitoring Technologies

Structural ConditionMonitoring Technologies

Structural Integrity

Life Cycle Management Technologies

Very High

Minimal

Low

Moderate

Moderately High

High

Application Frequency

Technology Readiness Level

6

TRL 5-7HighDigital Optical CorrelationMonitor and trend zero load residual strain

TRL 7-9Field: ModerateDepot: Low

X-ray diffractionMonitor and trend surface residual stress

TRL 9MinimalUltrasonically induced shot peening

Improve material and extend life

Cold expansion of structural holes

Induced positron analysis

Relate rotating system loads to fixed system parameters

Regime recognition and damage accumulation

Technology

TRL 9MinimalImprove material and extend life

TRL 5-7IPA-S: ModerateIPA-V: Low

Monitor and trend material condition

TRL 5-7Very HighDetermine dynamic component loads

TRL 7-9Very HighMonitor component usage and environments

Readiness Level

Application FrequencyApplication

Example Applications ofEnabling TechnologiesExample Applications ofEnabling Technologies

TRL 5-7HighDigital Optical CorrelationMonitor and trend zero load residual strain

TRL 7-9Field: ModerateDepot: Low

X-ray diffractionMonitor and trend surface residual stress

TRL 9MinimalUltrasonically induced shot peening

Improve material and extend life

Cold expansion of structural holes

Induced positron analysis

Relate rotating system loads to fixed system parameters

Regime recognition and damage accumulation

Technology

TRL 9MinimalImprove material and extend life

TRL 5-7IPA-S: ModerateIPA-V: Low

Monitor and trend material condition

TRL 5-7Very HighDetermine dynamic component loads

TRL 7-9Very HighMonitor component usage and environments

Readiness Level

Application FrequencyApplication

7

Operational Environment: Topography: Climate:► Elevation ► Hot► Desert ► Cold► Tropical ► Temperate► Maritime ► etc.

+

% Total D esign D am age by R eg im e

0%

10%

20%

30%

40%

50%

60%

Ban

ked

Turn

GA

G C

ycle

s

Fwd

Leve

lFl

ight

Take

-Off,

Clim

b, D

esce

nt

Pullo

ut

Side

& R

ear

Flig

ht

Con

trol

Rev

ersa

l

Hov

er

Aut

orot

atio

n

Land

ing

& T

axi

%To

tal D

esig

n D

amag

e

D esignActual

%Design Damage by Regime

Tim e in R egim e

0

10

20

30

40

50

60

70

80

Ban

ked

Turn

GA

G C

ycle

s

Fwd

Leve

lFl

ight

Take

-Off,

Clim

b, D

esce

nt

Pullo

ut

Side

& R

ear

Flig

ht

Con

trol

Rev

ersa

l

Hov

er

Aut

orot

atio

n

Land

ing

& T

axi

%Ti

me

or N

o. E

vent

s pe

r Hou

r

DesignActual

%Time in Regime

Monitor Component Usageand Environments

Monitor Component Usageand Environments

Compare operational usage with design assumptions to: ► Determine potential for

safe fatigue life extension► Isolate component early

removal drivers.

Usage monitoring application and benefits being demonstrated for AH-64 and UH-60.8

Determine Dynamic Component Loads

Determine Dynamic Component Loads

Regime-based damage accumulation is conservative and does not account for load sequence effects.Analyze Flight Loads Survey data using appropriate statistical methods:► Neural Networks► Genetic Algorithms► Holometrics► Regression Analysis

Develop algorithms that relate:► Flight parameters and fixed-system strains► Dynamic component loads and strains

Apply algorithms to fleet aircraft to:► Monitor high fidelity loads and sequences ► Analyze fatigue damage accumulation in

dynamic componentsAlgorithms reproduce flight recorded loads to accurately predict dynamic component fatigue damage.

Loads monitoring is being evaluated by the Aviation Engineering Directorate.9

Monitor and TrendZero Load Residual Strain

Monitor and TrendZero Load Residual Strain

Features and benefits: ► Portable, single-camera system► Fast 3D capture and processing ► Uses available lighting► Network-enabled ► Variable-zoom lens► High-resolution surface maps ► S/W produces accurate 3D surface info

►Non-contact measurements of surface deformation.►Deformation corresponds to plastic strain.►Trends indicate accumulated fatigue damage. ►Applicable to:

• Micro measurements• Macro measurements

0.0005in features

► Analyze deformation ► Assess surface damage► Detect and characterize

defects

3D digital optical correlation is being evaluated by AMRDEC for:• Metal alloy strain deformation• Composite material delamination

10

SensorCritical Surface

Surface Features

Monitor and TrendZero Load Residual Strain

Monitor and TrendZero Load Residual Strain

Approach:► Map residual stress ► Correlate residual

stress with usage► Assess adverse trends► XRD is applied in the

field or at the depot

Use x-ray diffraction (XRD) to measure, map, and trend changes in residual stress to assess usage-related degradation and predict impending rework or retirement.

Track residual stress:► Obtain XRD data over time► Map stress distribution► Track degradation► Relate to operational usage► Augment decisions:

Rework? Continue use?Retire? Modify use?

Benefits:► Reduce Cost► Increase Readiness► Enhance Safety

Monitor and Trend Surface Residual Stress

Monitor and Trend Surface Residual Stress

Duty Cycles

Res

idua

l Stres

s

Mea

sure

men

t (RSM

©)

0 10,000 20,000

threshold

Duty Cycles

Res

idua

l Stres

s

Mea

sure

men

t (RSM

©)

0 10,000 20,0000 10,000 20,0000 10,000 20,000

threshold

Depot/Rework Facility XRD

Field Portable XRD

Heavy DutyAccurateRepeatableFastFlexibleAuto Data

Heavy DutyAccurateRepeatableFastFlexibleAuto Data

12

TMTM

Inspect, Trend ComponentMaterial Condition

Inspect, Trend ComponentMaterial Condition

Benefits:► Map and track degradation. ► Correlate with usage.► Assess adverse trends.► Predict impending failures.► Predict remaining useful life.

► Induced Positron Annihilation (IPA) measures, maps, and trends component material condition at the lattice level.

► Monitor material degradation prior to crack initiation and assess continued safe usage, rework, or retirement.

Key Features:► High Sensitivity: Positrons probe

interstitial lattice sites.► Defects have more low

momentum free electrons. ► Atomic level impurity provides

unique signatures.► S-parameter quantifies

mechanically induced defects.► Damage quantified as compared

to material baseline.

IPA is being evaluated by AMRDEC and SOAR(A) on retired Chinook aft rotor shafts.

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S = A/B

A

Peak Energy 511 keV

B

COUNTS

S-Parameter

105 lattice sites probed

β+

β+β+β+

β+

β+β+

e-

γ511 keV

γ 511 keV

β+

B+

Positron Emitter IPA-S Probe

105 lattice sites probed

β+

β+β+β+β+

β+β+

β+β+β+

e-

γ511 keV

γ 511 keV

β+

B+

Positron Emitter IPA-S Probe

13

Ultrasonic Peening: Enhance structural integrity by introducing compressive residual stresses in components.

Benefits of Ultrasonic Peening: ►High quality peening ►Maximum fatigue life improvement ►Clean, quiet, and easy to control►Directly on part► In situ / minimum disassembly

Improve Safe Life ofDynamic ComponentsImprove Safe Life of

Dynamic Components

Principle:►Sine wave generated by acoustic block, amplified and

transmitted to balls in treatment chamber ►Chamber tailored to each application►Random ball displacement results in uniform peening

►Balls sized for each application►Computer controls peening:

● Intensity Time

Avion and Sonats are teamed on Army Phase I SBIR to demonstrate field repair of blended surfaces with portable ultrasonic peening.

14

Cold expand dynamic component fatigue-susceptible holes: ► Split Sleeve ► ForceMate Bushings

Forestalls fatigue crack initiation and fatigue crack growth andextends the safe useful life by a factor of at least 3:1.

Cx reduces maintenance cost and increases fatigue life of dynamic components.

► Cost effective ► Adds no weight ► Arrests small cracks► Alternative to redesign

Improve Safe Life of Dynamic ComponentsImprove Safe Life of

Dynamic Components

► Simple, one-sided operation ► Works on common materials► Applicable in production► Applicable in rework

Cra

ck L

engt

h

Life

1 0 K s i1 2 K s i

1 5 K s i1 8 K s i

Shrink Fit BushingShrink Fit Bushing

Force Fit BushingForce Fit Bushing

Cra

ck L

engt

h

Life

1 0 K s i1 2 K s i

1 5 K s i1 8 K s i

Cra

ck L

engt

h

Life

1 0 K s i1 2 K s i

1 5 K s i1 8 K s i

Shrink Fit BushingShrink Fit Bushing

Force Fit BushingForce Fit Bushing

ForceMate bushings are being installed in UH-60; being considered for AH-64.

15

Structural Integrity LCMTechnologies are Available Structural Integrity LCM

Technologies are Available

► US Army combat helicopters are 30-year old designs, at mid-life, and are flying increasingly intense usage in harsh environments.► Proven technologies are available to manage dynamic component continuing safe operational usage.

► Monitor usage and damage accumulation:Regime recognition Loads monitoring

► Monitor and trend zero load residual strain:3D Digital Optical Correlation Trend fatigue damage

► Measure, map, and trend dynamic component:Residual stress Material condition

► Improve dynamic component safe useful life:Acoustically peen surface Cold expand holes

► US Army combat helicopters are 30-year old designs, at mid-life, and are flying increasingly intense usage in harsh environments.► Proven technologies are available to manage dynamic component continuing safe operational usage.

► Monitor usage and damage accumulation:Regime recognition Loads monitoring

► Monitor and trend zero load residual strain:3D Digital Optical Correlation Trend fatigue damage

► Measure, map, and trend dynamic component:Residual stress Material condition

► Improve dynamic component safe useful life:Acoustically peen surface Cold expand holes

16