1

Jere

my

B. J

acob

s&

Will

ard

L. C

astn

er

Labo

rato

ry R

epro

duct

ion

and

Failu

re A

naly

sis

of

Cra

cked

Orb

iter

Rea

ctio

n C

ontr

ol S

yste

m

Nio

bium

Thr

uste

r In

ject

ors

https://ntrs.nasa.gov/search.jsp?R=20070018135 2020-08-03T05:13:16+00:00Z

2

Pres

enta

tion

Out

line

•D

escr

iptio

n of

RC

S T

hrus

ter

•Th

rust

er/In

ject

or P

hoto

s &

Cro

ss S

ectio

ns•

Inje

ctor

Cra

ck D

escr

iptio

ns•

His

tory

of I

njec

tor C

rack

ing

•R

epro

duct

ion

of In

ject

or C

rack

ing

•B

row

nfie

ld S

peci

men

•H

ydro

fluor

ic A

cid

Test

s•S

peci

men

Loa

ding

Arr

ange

men

t•S

peci

men

#3

Res

ults

•Spe

cim

en #

5 R

esul

ts•T

est M

atrix

•K

ryto

x/B

rayc

oTe

sts

•Spe

cim

en L

oadi

ng A

rran

gem

ent

•Spe

cim

en #

13 R

esul

ts•T

est M

atrix

•C

oncl

usio

ns/R

ecom

men

datio

ns

3

Ende

avou

rSTS

-113

Lan

ding

4

RC

S Th

rust

er

5

Thru

ster

Cro

ss-S

ectio

n

6

RC

S In

ject

or

Sec

tione

d S

/N 1

20

Inje

ctor

Cro

ss S

ectio

n

7

RC

S Th

rust

er, S

/N 1

20

8

Cou

nter

bore

Cra

cks

Cou

nter

bore

loca

tions

9

Rel

ief R

adiu

s C

rack

s

Cra

ck e

xten

ding

from

relie

f ra

dius

tow

ards

aco

ustic

cav

ity

Pen

etra

ntin

dica

tion

10

RC

S Th

rust

er C

rack

ing

His

tory

•Th

ree

grou

ping

s of

cra

cked

thru

ster

s

•19

79 -

SN 1

28, 1

30, 1

32•

No

Dire

ct c

ause

of c

rack

ing

foun

d•

Cor

rect

ive

actio

ns•

Dev

elop

ed u

ltras

onic

insp

ectio

n te

chni

que

•

Acc

ompl

ishe

d on

e tim

e ul

traso

nic

insp

ectio

n of

flee

t •

Add

ed u

ltras

onic

insp

ectio

n to

man

ufac

turin

g flo

w (p

re b

ake-

out)

•C

ompl

eted

100

mis

sion

Qua

l tes

t with

SN

130

& 1

32•

1982

-SN

322

, 415

, 416

, 433

•C

rack

ing

attri

bute

d to

HF

etch

ant a

nd 6

00 F

insu

latio

n ba

ke-o

ut•

Cor

rect

ive

actio

ns

•E

limin

ate

etch

ants

from

man

ufac

turin

g pr

oces

s •

Add

ed u

ltras

onic

insp

ectio

n im

med

iate

ly a

fter b

ake-

out c

ycle

•

2004

-SN

120

•C

ount

er b

ore

crac

ks fo

und

near

new

noz

zle

EB

wel

d•

Firs

t tim

e su

ch c

rack

s fo

und,

dis

cove

red

inci

dent

ally

(pen

etra

ntin

spec

tion)

•R

elie

f rad

ius

crac

ks s

imila

r to

1979

/198

2 su

bseq

uent

ly fo

und

11

Thru

ster

Man

ufac

turin

g Ti

mel

ines

1979

1982

2004

Thru

ster

SN

128

130

Qua

ltes

t13

2Q

ualt

est

322

415

416

433

120

Hig

h us

age

Preb

ake

ultr

ason

icn/

an/

an/

a1/

26/8

2 1/

28/8

2 N

o C

rack

s fo

und

No

Cra

cks

foun

d

No

Cra

cks

foun

d

No

Cra

cks

foun

d

n/a

n/a

12/1

5/82

Cra

cked

n/a

n/a

4/29

/79

No

cra

cks

fo

und

n/a

o.k.

4/2/

04

Cra

cked

Post

bak

eU

ltras

onic

(One

tim

e fl

eet i

nsp.

af

ter 1

28 fo

und)

n/a

4/14

/79

Cra

cked

@ M

AC

4/12

/79

Cra

cked

@ M

AC

n/a

n/a

n/a

Post

bak

eU

ltras

onic

(Mfg

. Ins

p.In

itiat

ed

afte

r 322

foun

d)

n/a

n/a

n/a

2/11

/82

Cra

cked

per

Sp

ecia

l U

ltras

onic

12/1

4/82

Cra

cked

12/7

/82

Cra

cked

Post

bak

eLe

ak te

st3/

14/7

9C

rack

edo.

k.o.

k.2/

11/8

2C

rack

edn/

an/

a

Pene

tran

t Ins

pect

ion

@ W

STF

n/a

n/a

n/a

n/a

n/a

n/a

Leak

Tes

t2/

12/7

93/

1/79

11/1

5/78

1/30

/82

Torq

ue B

olts

2/13

/79

3/2/

7911

/16/

781/

30/8

2

Insu

latio

n B

ake

2/28

/79

2/7/

82

12

Labo

rato

ry R

epro

duct

ion

of In

ject

or C

rack

ing

•Tes

t Pur

pose

•Id

entif

y O

ffend

ing

Spe

cies

•Id

entif

y C

ondi

tions

for C

rack

ing

•E

stab

lish

Con

ditio

nal T

hres

hold

s•T

empe

ratu

re•S

tress

Lev

el•T

ime,

etc

.•T

est P

roto

col

•Fo

llow

ed G

uida

nce

in 1

982

CA

R•A

pply

HF

Etc

hant

to C

103

•Cov

er w

ith T

itani

um•S

tress

to 3

0 K

SI

•Hea

t to

600F

for 4

8 hr

s•L

abor

ator

y R

epro

duct

ion

of C

rack

ing

Was

Enh

ance

d•

Whe

n 19

82 C

rack

ed “B

row

nfie

ld” S

peci

men

Was

Fou

nd•

Whe

n B

row

nfie

ld F

ract

ure

Sur

face

Was

Sam

e A

s Th

rust

er’s

13

The

“Bro

wnf

ield

” Sp

ecim

en…

14

HF

Etch

antT

ests

/Spe

cim

en L

oadi

ng

Gen

eric

Tes

t Pro

toco

l:

1.C

ut &

Pre

p C

103

Test

Sam

ple

2.P

lace

Har

dnes

s In

dent

atio

ns a

t M

ax T

ensi

le S

tress

Loc

atio

n

3.C

over

With

Tita

nium

, Cla

mp,

&

App

ly C

onst

ant L

oad

(Yie

ld

Stre

ngth

/ 40

KS

I)

4.A

pply

HF

Etc

hant

to C

revi

ce

5.H

eatin

g P

rofil

e, 4

00F-

600F

for

48 H

ours

6.R

emov

e fro

m T

est,

Cle

an,

Exa

min

e U

nder

Mic

rosc

ope

/ SE

M

7.B

end

to O

pen

Cra

cks

8.E

xam

ine

Frac

ture

Sur

face

M

orph

olog

y to

Est

ablis

h Fa

ilure

M

ode

Load

= C

onst

ant

(Equ

ival

ent t

o 40

KSI

)

Varia

bles

= T

, t, H

F C

once

ntra

tion

0.75

”

S.S.

Cla

mp

σ Max

Ten

sion

Can

tilev

er T

est C

onfig

urat

ion

HF

Etch

ant

Ti 6

-4

•Sp

ecim

en D

imen

sion

s•

≈1”

X 0

.2” X

0.0

40”

•D

MA

Tes

t Equ

ipm

ent

•Tr

end

Load

, Def

lect

ion,

Tem

p, T

ime

•D

ry A

ir P

urge

C10

3H

ardn

ess

Inde

nts

15

Spec

imen

#3

–H

F +

600F

Ope

ned

Afte

r Cle

anin

g

Spec

imen

#3

–IG

Fra

ctur

e

17

Spec

imen

#5

–H

F +

600F

•3

IG C

rack

Initi

atio

n Si

tes

(Cor

resp

ond

to H

ardn

ess

Inde

nts)

18

Spec

imen

#5

–“P

opco

rn”

Nea

r Orig

inN

ear T

erm

inat

ion

19

Spec

imen

#5

–C

lean

ed a

nd B

ent

As-

Test

ed

As-

Cle

aned

As-

Ben

t

20

HF

Expo

sure

Tes

t Mat

rix

Spec

imen

#C

103

Can

tilev

er B

eam

Tes

ts (C

onst

ant L

oad)

X =

Cra

cks

1Vi

se+

Nb

etch

+ Ti

cov

er+

dry

+ 40

KSI

+ 60

0°F

+ 48

hrs

2Vi

se+

Nb

etch

+ dr

y+

Ti c

over

+ 40

KSI

+ 60

0°F

+ 48

hrs

3Vi

se+

Ti c

over

+ 40

KSI

+ N

bet

ch+

dry

+ 60

0°F

+ 48

hrs

X

4Vi

se+

Nb

cove

r+ 4

0KSI

+

Ti e

tch

+ dr

y+

600°

F+

48hr

s

5Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y+

600°

F+

48hr

sX

6Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y+

400°

F+

48hr

s

8Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y+

500°

F+

48hr

sX

(min

or)

9Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y+

600°

F+

3hrs

X

10Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y+

600°

F+

48hr

s+

70°F

+ H

2O (3

X/da

y)

+ 26

0hrs

X

11Vi

se/H

ard

+ Ti

cov

er+

40KS

I+

Nb

etch

+ dr

y +

600°

F+

168h

rsX

12Vi

se/H

ard

+ N

bco

ver+

40K

SI+

Nb

etch

+ dr

y+

600°

F+

48hr

sX

13Se

e Ta

ble

2

14H

ard

+ Ti

cov

er+

40KS

I+

air

+ +

600°

F+

48hr

s

21

Kry

tox

143A

C T

ests

•Wha

t is

Kry

tox?

•P

erflu

orop

olye

ther

(PFP

E) P

olym

er•

Als

o R

efer

red

to a

s a

Syn

thet

ic O

il•

Com

pose

d of

Car

bon,

Oxy

gen

and

Fluo

rine

•Why

Tes

t Kry

tox?

•U

sed

in T

hrus

ter M

anuf

actu

ring

•C

onta

ined

Flu

orin

e•

Orig

inal

Com

patib

ility

Tes

ts a

t 110

0F n

ot 6

00F

•X

PS

Ana

lysi

s S

how

ed P

FPE

on

Frac

ture

Sur

face

22

Kry

tox

Test

s/Sp

ecim

en L

oadi

ng

3–Po

int B

end

(Con

stan

t Def

lect

ion)

Def

lect

ion

Har

dnes

s In

dent

s (T

op &

Bot

tom

Sur

face

s)

Stai

nles

s St

eel

C10

3≈

1.0

X 0.

15 X

0.0

43

10-3

8 Sc

rew

2.0”

PFPE

Oil

(Ten

sion

Sur

face

)

3–Po

int B

end

(Con

stan

t Def

lect

ion)

Def

lect

ion

Har

dnes

s In

dent

s (T

op &

Bot

tom

Sur

face

s)

Stai

nles

s St

eel

C10

3≈

1.0

X 0.

15 X

0.0

43

10-3

8 Sc

rew

2.0”

PFPE

Oil

(Ten

sion

Sur

face

)

23

Spec

imen

#13

–K

ryto

x +

600F

24

Spec

imen

#13

–K

ryto

x +

600F

Mis

sing

Gra

ins

at C

rack

Orig

in“P

opco

rn” o

n Fr

ee S

urfa

ce +

IG

Cra

ck

25

Kry

tox

Expo

sure

Tes

t Mat

rix

Spec

imen

#C

-103

Can

tilev

er B

eam

Tes

ts (C

onst

ant L

oad)

X =

Cra

cks

13H

ardn

ess

+ Ti

cov

er+

40KS

I+

Kryt

ox+

600°

F+

48hr

sX

14Se

e Ta

ble

I

15H

ardn

ess

+ Ti

cov

er+

40KS

I+

Kryt

ox+

400°

F+

48hr

s

16H

ardn

ess

+ Ti

cov

er+

40KS

I+

Kryt

ox+

500°

F+

48hr

sX

(min

or)

17H

ardn

ess

+ Ti

cov

er+

40KS

I+

Kryt

ox+

600°

F+

96hr

sX

18H

ardn

ess

+ Ti

cov

er+

40KS

I+

Kryt

ox+

600°

F+

3hrs

X

Spec

imen

#C

-103

Thr

ee-P

oint

-Ben

d Te

sts

(Con

stan

t Def

lect

ion)

29H

ardn

ess

+ no

Ti

+ >

45KS

I +

Kryt

ox+

600°

F+

1hrs

X

30N

o in

dent

+ no

Ti

+ >

45KS

I+

Kryt

ox+

600°

F+

1hrs

31H

ardn

ess

+ no

Ti

+ >

45KS

I+

Bray

co+

600°

F+

1hrs

Spec

imen

#C

b752

Thr

ee-P

oint

-Ben

d Te

sts

(Con

stan

t Def

lect

ion)

32H

ardn

ess

+ no

Ti

+ >

45KS

I+

Bray

co+

600°

F+

23 h

rsX

26

Con

clus

ions

/ R

ecom

men

datio

ns

•Cra

cks

Suc

cess

fully

Rep

rodu

ced

in L

abor

ator

y•S

imul

tane

ous

Con

ditio

ns N

eces

sary

for C

rack

ing

•M

echa

nica

lly D

istu

rbed

/Col

d W

orke

d S

urfa

ce•

Ext

erna

lly A

pplie

d S

usta

ined

Stre

ss n

ear Y

ield

•Fl

uorin

e C

onta

inin

g Fl

uid

•S

usta

ined

Tem

pera

ture

abo

ve 4

00F

•C

rack

ing

Occ

urre

d D

urin

g M

anuf

actu

ring

•O

nly

Tim

e al

l Fou

r Con

ditio

ns a

ct S

imul

tane

ousl

y•

Elim

inat

e us

e of

Flu

orin

e w

ith N

iobi

um

•S

ame

Cra

ckin

g M

echa

nism

Ope

ratin

g in

HF

and

PFP

E F

luid

s•

Spe

cific

Cra

ckin

g M

echa

nism

not

Iden

tifie

d

27

Bac

k-U

p

28

Loca

tion

Of C

rack

s

29

Frac

ture

Fac

e of

Rel

ief R

adiu

s C

rack

30

Cle

avag

e Fr

actu

re o

n S/

N 1

20

Ope

ned

Rel

ief R

adiu

s (B

etw

een

Hol

es J

& K

)

31

Com

paris

on o

f Thr

uste

r Fai

lure

Ana

lysi

s Fi

ndin

gs

1979

1982

2004

Thru

ster

SN

128

130

132

322

415

416

433

120

YES

YES

Frac

ture

D

isco

lore

dYE

SYE

SYE

SYE

SYE

SYE

SYE

SYE

S

Cra

ckEx

tens

ion

Bey

ond

Dis

colo

ratio

n

No

NO

NO

NO

NO

NO

NO

NO

Surf

ace

Che

mis

try

F,O

,CF

F,O

,CF

FF

FF,

O,C

YES

No

serv

ice

hist

ory

YES

YES

YES

17 fl

ight

s,N

oN

o se

rvic

e hi

stor

y

YES

YES

No

serv

ice

hist

ory

Cra

ck In

itiat

ed in

M

fg.

YES

YES

YES

YES

Cra

cked

100

%In

terg

ranu

lar

YES

YES

YES

YES

Cra

ckEx

tens

ion

In

serv

ice/

Qua

l Tes

t

No

serv

ice

hist

ory

Qua

l, N

oQ

ual,

No

No

serv

ice

hist

ory

32

Dis

cuss

ion

•C

hem

ical

bre

akdo

wn

of th

e P

FPE

pol

ymer

cha

in is

a w

ell k

now

n ph

enom

ena

to th

e lu

bric

atio

n co

mm

unity

.

•Th

e m

echa

nism

tend

s to

follo

w th

ree

step

s:1.

The

met

al/o

xide

sur

face

reac

ts w

ith fl

uorin

e fro

m th

e P

FPE

to fo

rm

a Le

wis

aci

d (i.

e. N

bF3

/ NbF

5).

2. T

he L

ewis

aci

d ca

taly

zes

the

clea

vage

of t

he p

olym

er c

hain

.3.

The

bro

ken

poly

mer

cha

in c

an re

act w

ith w

ater

to fo

rm a

car

boxy

lic a

cid

term

inat

ed g

roup

rele

asin

g hy

drof

luor

ic a

cid.

Che

mic

al B

reak

dow

n of

Kry

tox

PFPE

Pol

ymer

Kry

tox

(Per

fluor

opol

yeth

er)

CF 3

CF 3

–CF 2

–CF 2

–O —

CF 2

–CF 2

–O —

CF 2

–CF 3

Fm Le

wis

Aci

d

STEP

1

STEP

2

STEP

3

33

Inje

ctor

Cra

ck F

light

Rat

iona

le R

oad-

Map