Apollo Experience Report Ground-Support Equipment

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N A S A T E C H N I C A L N O T E NASA TN D-791

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APOLLO EXPERIENCE REPORT -

GROUND-SUPPORT EQUIPMENT

James S. Cooper

Lyndon B. Johnson Space Center

Houston, Texas 77058

N A T I O N A L A E R O N A U T I C S A N D SPA CE A D M I N I S T R A T I O N W A S H I N G T O N , D. C. A P R I L 1 9 7



1. R e p o r t N o .

NASA TN D-7918

4. T i t l e a n d S u b t i t l e I 5. R e p o r t D a t e

2. G o v e r n m e n t A c c e s si o n No. 3. Rec ip ien t ' s Cata log No.

APOLLO EXPERIENCE REPORTGROUND-SUPPORT EQUIPMENT

7. A u t h o r ( s )

James S. Cooper

A p r i l 1975

JSC- 07482~8. P e r f o r m i n g O r ga n i z a t io n R e p o r t No.

JSC S-415

9. P e r f o r m i n g O r g a n i z a t io n N a m e a n d A d d r e s s

10. W o r k U n i t N o .

914- 50- 00-00-72Lyndon B. Johnson Space CenterHouston, Texas 77058

19. S e c u r i t y C l as s if . ( o f t h i s r e p o r t )

11. C o n t r a c t o r G r a n t No

20 . Securi ty Classi f .

13. Ty p e o f R e p o r t a n d P e r io d C o v e r e d

Technical Note2. Sponsor ing Agenc y Name and Address

14. Sponsor ing Agency Codeational Aeronautics and Space AdministrationWashington, D.C. 20546

25nclassified Unclassified

15. S u p p l e m e n t a r y N o t e s

$3.25

16. Abs t rac t

This report is a sum mary of the experience gained in management of the ground-support-equipment and site-re adin ess activity for the Apollo Prog ram . The discussion is divided intonine repres enta tive ar ea s. The fi rs t seven sections generally perta in to the design of equipmentand facilities, although some operational aspects are examined as we l l . The organization f orensuring si te read ine ss and the maintenance of ground-support equipment ar e discussed in thelas t two sections. Recommendations for use in future progra ms are given i n the ar e as of designconsiderations, cleanl iness requirements, periodic evaluation of changing requirements,maintenance and overhaul, specia l te st equipment, site-activation schedule coordination, andsch ema tics fo r ground-support equipment.

18. D i s t r i b u t i o n S t a t e m e n t

STAR Subject Category:12 (Astronautics, General)



APOLLOEXPERIENCEREPORT

EDITORIAL COMMITTEE

The materi al submitted fo r the Apollo Experience R eports

(a se r i e s of NASA Technical Notes) was reviewed and ap-

proved by a NASA Editorial Review Board at the Lyndon B.

Johnson Space Cen ter consisting of the following member s :

Scott H . Simpkinson (Chairman), Richard R. Baldwin,

James R. Bates, William M. Bland, J r . , Aleck C. Bond,

Robert P. Burt, C hr is C. Cr itzo s, John M. Eggleston,

E. M. Fields, Donald T. Gregory, Edward B. Hamblett, J r . ,Kenneth F. Hecht, David N. Holman (Editor/Secretary),

and Carl R. Huss. The prime reviewer for this reportwas Scott H. Simpkinson.



CONTENTS

Section

SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DESIGN STANDARDIZATION . . . . . . . . . . . . . . . . . . . . . . . . . .

Computerized Control Station . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Terminal Distributors

and Patchable Connectors . . . . . . . . . . . . . . . . . . . . . . . . .

Fluid-Servicing Equipment . . . . . . . . . . . . . . . . . . . . . . . . .

DESIGN INADEQUACIES . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cryogenic Simplification . . . . . . . . . . . . . . . . . . . . . . . . . . .

Protective Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Checkout Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . .

Flexible Hoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Electrical Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Overpressure Problems . . . . . . . . . . . . . . . . . . . . . . . . . . .

GROUND POWER SYSTEM . . . . . . . . . . . . . . . . . . . . . . . . . . .

Direct-Current Ground Power System . . . . . . . . . . . . . . . . . .

Alternating-Current Ground Power System . . . . . . . . . . . . . . . . .

SPECIAL TEST EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . .CLEANLINESS AND ENVIRONMENTAL CONTROL . . . . . . . . . . . . . .

Environmentally Controlled Areas . . . . . . . . . . . . . . . . . . . . .

Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

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Section

AUTOMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Page

14

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15utomated Checkout

Automated Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COMMON-USE EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . .

MANAGEMENT O F GROUND-SUPPORT EQUIPMENTAND SITE READINESS . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAINTENANCE AND OVERHAUL . . . . . . . . . . . . . . . . . . . .

RECOMMENDATIONS AND CONCLUSIONS . . . . . . . . . . . . . . . . . .

Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .REFERENCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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FIGURES

Figure

1 Acceptance checkout equipment (ACE) control room . . . . . . . . .2 Standard 60-conductor cable . . . . . . . . . . . . . . . . . . . . .

3 Standard 38-conductor cable . . . . . . . . . . . . . . . . . . . . .

4 Electrical terminal distributor

(a) Front view . . . . . . . . . . . . . . . . . . . . . . . . . . . .(b) Rearview . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 Standardized connector installed

(a) Patchable configuration . . . . . . . . . . . . . . . . . . . . .(b) Cable installation . . . . . . . . . . . . . . . . . . . . . . . . .

6 Standardized connector . . . . . . . . . . . . . . . . . . . . . . . .

7 Cryogenic tank . . . . . . . . . . . . . . . . . . . . . . . . . . . .

8 Integrated checkout station . . . . . . . . . . . . . . . . . . . . . .

9 Flexible hose s

10

(a ) Flexible hose a t console . . . . . . . . . . . . . . . . . . . . .

(b ) Flexible hose routing . . . . . . . . . . . . . . . . . . . . . .Har dl ines

(a) Console installation . . . . . . . . . . . . . . . . . . . . . . .(b) Equipment routing . . . . . . . . . . . . . . . . . . . . . . . .

11 Alternating-current to direct- curren t

converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

12 Dire ct-c urr ent power supplies . . . . . . . . . . . . . . . . . . .

13 Cleanroom garmen ts . . . . . . . . . . . . . . . . . . . . . . . . .

14 Fuel control panels . . . . . . . . . . . . . . . . . . . . . . . . .

15 Fuel contro l panel details . . . . . . . . . . . . . . . . . . . . . .

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V



APOLLO EXPERIENCE REPORT

GROUND-SUPPORT EQU IPMENT

By James S. Cooper

Lyndon B. Johnson Space Center

S U M M A R Y

The responsibility for ground-support equipment and site re adin ess comprised

the exerci sing of management control over two pr ime space craft contractor s. This

responsibility included providing total capability for vehicle test and checkout at thefactories, development centers, and launch sites, and ensuring operationally ready

faci li ti es and support equipment for each site/facility/vehicle combination.

To meet scheduled prog ram req uiremen ts, unique approaches such as standard-

ization of ca bl es , util ization of common-use equipment, and automation of vehicle

checkout were adopted. The experience gained in the management and development of

ground-support equipment in the ar ea s of design standardization, design inadequacies,

ground power sys te ms, special tes t equipment, cleanl iness and environmental control,

automation, common-use equipment, si te readiness , and maintenance and overhaul

would be beneficial i f applied early i n future programs.

INTRODUCTION

The responsibi lity f or ground-support equipment (GSE) and site r eadiness was

assigne d to an organization within the pol lo Spacecraft Progr am Office. This orga-

nization exercis ed GSE management control over the 'two pr ime spacec raft con trac tor s,

Management responsibility encompassed providing total capability for vehicle test and

checkout at the fac tor ies, development cen ters , and launch site s, and ensuring opera-

tionally ready facilities and support equipment for each site/facility/vehicle combina-

tion.

Several aspects of the GSE program a r e examined in this report. Each aspectw a s importa nt to the development of the total progr am and could mer it presentation

as a se pa ra te report ; however, a more effective presentation r esu lt s fr om combining

them into a single report. The discussion of the Apollo GSE program experience is

followed by recommendations fo r use i n future prog rams . These recommendations

are not linked to specific proble ms; instead, the recommendations are based on gen-

eral pr ac ti ce s that evolved and proved to be useful during the Apollo Program.



A s an aid to the rea de r, where nece ssa ry the original units of mea sur e have beenconverted to the equivalent value in the SystGme International d'Unit6s (SI). The SIunits are written fi rs t, and the original units a r e written parenthetically t hereaf ter.

D E S I G N S T A N D A R D I Z A T I O N

The GSE sy st ems were designed to support simi la r vehicle tes t req uire men tsand procedures at the various checkout facilities and thus provided the capability toobtain a close correlation of test data and to interchange GSE units among fac ili tie s.Ground- support-equipment end-item design was standardized to reduce the number of

different units, to reduce the GSE manufacturing time, and to reduce the GSE andspacecraft test time. Standardization of the GSE allowed a reduction in the numberof sp ar e par ts requir ed and a reduction in the operating personnel trainin g requi re-ments. Furthe r, the GSE system-standardization approach permitted maximum us eof GSE units among checkout facilities and w a s an important a ss et in meeting thedemanding Apollo schedules.

C o m p u t e r i ze d C o n t r o l S t a t i o n

The complexity and complet eness of Apollo s ys te ms checkout neces sitat ed ahighly complex network of GSE at each te st site, To control and monitor this network,GSE units were electrically connected to centrally located computerized control sta-tions (fig. 1). Standardization of calibration data and some computer pr ogra ms was

Figure 1.- Acceptance checkout equipment (ACE) control room.

2



possible because the networks at the various test sit es were sim ila r. This standard-

ization, coupled with tes t requiremen ts and procedural simila rity, permitted a close

correl ation of te st data fr om the factory to the launch pad. Thus, the probability of

detection of any s pacec raft sys tem s degradation during preflight testing was enhanced.

E e c tr a I CablesMinimization of the types of ele ctr ica l signa ls req uired to control and monitor

the per forman ce of GSE permit ted standardization of interconnecting cab les . This

standardization res ult ed in the procu rement of two basic ca ble types.

1. A cable containing 60 individually shielded conductors, with insulated sh ields

2. A cable containing 38 conductors, consisting of 19 individually shielded

twisted pair s

During manufacturing, the cable types were terminated in 61- and 62-pin con-

nectors. In a single A-size drawing (21.6 by 28 centimeters (8. 5 by 11 inches)), thevariations of a speci fic cable type were documented. Dash number s were assigned to

specify different lengths and connector types (figs. 2 and 3). The us e of stan dard

cable types resulted i n a significant reduction i n cable fabrication tim e and cost .

Without t his standardized design, it would have been difficult to deliver the ele ctr ica l

GSE cables (approximately 25 000 of a ll types) in time to support Apollo testing.

E l e c t ri c a l T e r m i n a l D i s t r i b u t o r s

and P a t ch a b le C o n n e c t o r s

Electrical signal routing among GSE units (from GSE to facility and from GSE

to s pacecr aft) was accomplished by means of cab les that we re connected to ele ctr ica ltermin al distri butor s (ETD) units. (fig. 4 ) . A patchable connector, developed specifi-

cally fo r the Apollo Pro gr am to perm it interchang e of signa ls within a cable, made

ETD design standardization possible (figs. 5 and 6). The patchable halves of these

connec tors were mounted on removable bulkheads in standar d equipment rac ks. Thi s

arrang ement provided a prepatch capability and interchangeability. Ele ctr ica l signa ls

were routed by cable patching within the ETD.

Because of simila rity and close manufacturing surveillance, qualification test-

ing was accomplished on a single rack of the ETD; other ra ck s wer e qualified by

similar ity. Pa rt s were purchased in large quantities, a procedure that minimized

unit cost s. Standardized design of ETD units allowed additional savings through areduced sp ar e parts inventory.

3



4

CONNECTOR ME414-0539-0001 1 REQDCONTACT, ME418-0018-0002 6 1 REQDGLAND ZZM6320-22C 1 REQDW A S H E k , Z Z M 8 0 2 0 - 2 4 E , 1 REOD 8ADAPTER, MS3057-32A 1 REQD

CONNECTOk, (SEE TAB LE I)S LE EV E, ~ 6 1 0 0 4 - 1 5 R G 6 0 8 5 4 - 15 1 EQD(REMOVE GROMMET FOLLOWER, BEF ORE INS TAL LAT ION 'DUSTCAP, G317R246-1B 1 REQD

@

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A END P 1 . P 2 B END(SOCKET) <CABLE MP 57 2- 02 21 -0 00 1

1

I.c 7D 2E 2F 2D 4E 4F4D 5E 5F5

D 7E 7F7

G2H 2J 2G 4H 4J4

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1. F A BR ICA T E PE R M A 0 3 0 3 - D l 2 0 T Y P E I .

2 . PYL E NATIONAL, CHICAGO, ILLINOI S, OR EQUI VAL ENT.3 . GLENAIR. INC., GLENDALE. CALIFORN IA, OR EQUIVALE NT)

EXAMPLE OF COMPLETE PART NO.M D 4 1 1 - 0 1 9 7 - 3 0 1 5

7- AST TH R EE DIGITS O F D A S H NO. INDICATE CABLEASSEMBLY LENGTH IN F E E 1 = 15 F IT

INDICATES "6 " END CONNECTOR I S M S 3 1 2 6 E 2 4 - 6 1 P Y

FOR APOLLO USE ONLY

T A B L E I

FIRST DIGITOFDASH NO.

-0xxx

-1xxx- 2 x x x

- 3 x x x

-4xxx

- 5 x x x

- 6 X X X

- 7xxx

-axxx

-YXXX

3 END:ONNECTORi n S 3 1 2 6 E 2 4

- 6 1 P

-61PW

- 6 1 P X

- 6 l P Y

- 6 1 P Z

-61s

-61SW

- 6 1 S X

- 6 1 S Y

- 6 1 5 2

OLERANCES, EXCEPT AS NOTED T O L E R A N C L S ,013 THRU , 0 4 0 :t 00 1 - ,001 , 5 0 1 TH Rl I , 7 5 0 : + . 0 0 5 - .001 CODE IDEN

O N H O L t S ,041THRU ,130: t 002 - ,001

, 230 THRU ,500: t .004 - ,001

, 7 5 1 T HR U 1.000: t.007- 001NGLES f 0' DECIMALS .XX = A . 0 3 N O T E D , 1 3 1 T H RU , 2 2 9 : + ,003 , 0 0 1 1.001 THRU 2 , 0 0 0 : t .010 - . 0 0 1 03953

) R BY

.XXX = t.010 'DRILL'

N O R T H A M E R IC A N A V I A T I O N , I N C . STANDARD PARPACE an d I N F O R M A T I O N SY S TE M S D I V I S I O N

1 2 2 1 4 L AKE WOO D I )L VD.. DOWNEY, C A L I F O R N I A;HK BY- MD411-0197SPECIAL PURPOSE, ELECTRICAL- ,

rPPD

\PPD 60 CONDUCTOR S H E E T 1 OF 1

Figure 2. - Standard 60-conductor cable.



CONNECTOR (SEE TAB LE I)S L EE V E 6 3 1 4 - 4 0 5 1 7 - 6 C

O U S T C A P G 1 1 0 6 - 5 7 R 6 - 1 G1 R E O O ~

CONNECTOR ME414-0539-0001 1 REQDC ON TA CT M E 4 1 8 - 0 0 1 8 - 0 0 0 2 5 8 R E Q O

GLAND ZZM6320-24C 1 REQD 3WASHER ZZM8020-24E 1 E Q p @AOAPTEK MS 3057-3 2A 1 REQD

xx * . O 3N b L t 5

* 3 0 ' x x x = _ + . 0 1 0---R B Y

:HK B Y

A P P D

A P P D,

- P R E W T tP 2 ) P ER M A 0 1 0 6 - 0 0 9 - \ 1

N O T E E

'ORILL.

, 1 3 1 T HR U ,2 2 9 : t 0 0 3 - , 0 0 1 1 00 1 THRU 2.000: + . 0 1 0 - 0 0 1

,230 THRU ,500 : + ,004 - , 0 0 1

N O R T H A M E R IC A N A V I A T I O N , I N C .

S P A C E o n d INFORMATION SYSTEMS DIVISION

12214 L A K E W O O D B L V D , D O W N E Y , C A L I F O R N I A

STANDARD PARI

CABLE ASSEMBLY MD411-0190

19 TW PRS SHEET 1 OF 1

SPECIAL PURPOSE, ELECTRICAL- ,

B t N 0P 1 P 2

A EN 0

(SOCKET

C A B L E M P 5 7 2 - 0 2 1 9 - 0 0 0 2

I IA k LENGTH -1

A B

L 4 4 1M4 4 2K5 4 3L5 44M5 4 5K7 4 6L7 47M 7 4 8N 7 A 9

1 12

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A

1. FABRICATE PER MA03 03- 012 0 TYPE I

2. PYLE NATIONAL. CHICAGO, ILLINOIS, O R EQUIVALENT

3 . GLENAIR, INC. GLENDALE, CALIFORNIA, O R EQUIVALENT

4 . BENOIX CORP, SIDN EY, NEW YORK O R EQUIVALENT

@@@EXAMPLE OF COMPLETE PART NO.

M D 4 1 1 - 0 1 9 0 - 3 0 1 5

LAST THREE DIGITS OF DASH NO. INDICATE CABLE ASSEMBLLLENGTH IN FEET = 1 5 F T

INDICATES "6" EN0 CONNECTOR IS 8 3 - 3 2 3 6 4 0 - 8 1 K

FOR APOLLO USE ONLY

TABLE I

FIRST O I G I lOFDASH NO.

- 0 x x x

- l x x x

- 2 x x x

- 3 x x x

- 4 x x x

- 5 x x x

-6XXX

- 7 x x x

-8XXX

- 9 x x x

ONNECTOR: 3 - 3 2 3 6 4 0

'ON-

- 8 1 P I PIN

-81G

-811

- 8 1 K

PIN

PIN

PIN

TOLE RANC ES, EXCEPT AS NOTED T O L E R A N C E S . ~ ~ ~H R U .0 4 0 : t 0 0 1 - , 0 0 1 . 5 0 1 T HR U 7 5 0 : + , 0 0 5 - ,0 01 CODE IOEh

. - -. O N H O L E S , 0 4 1 THRU , 1 3 0 3 0 0 2 - , 0 0 1 , 7 5 1 T HRU 1 . 0 0 0 : + , 0 0 7 - , 0 0 1

Figure 3. - Standard 38-conductor cable.

5



.

r

(a) Fro nt view. (b ) Rea r view.

Figure 4. - Electrical terminal distributor.

(a) Patchable configuration. (b) Cable installation.

Figure 5. - Standardized connector installed.

6



2.- echanical clocking

Figure 6. - Standardized connector.

FI u d- Servicing EquipmentThe fluid-servicing requirements differed a t each tes t si te. In general, only

pres sur e checks, leak checks, flow checks, and water servicing were performed atthe manufacturing p lants and the development areas. However, the GSE designed fora complete servici ng operation at the launch site was used at all test areas to limitthe number of designs. Portability wa s a prima ry consideration in standardizingfluid ha rdware.

DES GN I NADEQUACI ES

A f t e r the GSE became operational, certain design inadequacies were evident.The se inadequacies, identified in design reviews, in equipment fai lur es, and in fail-

u r e mode and effects analyses, necessitated that protective devices be incorporated,that con strai nts be reevaluated, and that GSE sys tems be simplified to achieve accept-able operational performance.

7



Cryogenic Simplification

The design Of the cryogenic servicing system wa s influenced by weight restric-tions on the mobile serv ice stru ctur e. These restri ctio ns, in addition to a remote-contro l requi rement , led to the development of a system that used stowage tanks,pumping units, and vacuum- jacketed l ines to convey liquid oxygen and liquid hydrogenfr om the ground to the spacecraft (91-meter (300-foot) level). However, the heat leak

over this distance w a s grea ter than had been anticipated; ther efor e, a hydrogensubcooler w a s installed. This improvement provided, at best, a marginal transfersystem.

The weight res tric tion w a s eliminated when a counterbalance w a s added to themobile service stru ctur e. The remote-control requirement was deleted in favor oflocal control with pad-cl ear and remo te monitoring. Because of these changes, theenti re cryogenic servicing system w a s replaced with portable cryogenic tanks (fig. 7)and a simplified control system . The tanks we re filled , then lifted (by means of a nelevator ) to the appropr iate s pace craf t level.

Use of the portable-tank concept resolved the heat-leak problem and enabled

the removal of stowage tanks, tra nsf er uni ts, hydrogen subcooler , and vacuum-jacketed lines. Use of this concept al so permit ted local control at the spacecra ftlevel.

Figure 7.- Cryogenic tank.



Pro tec t i ve Dev i ces

Protec tive d evice s wer e incorporated after initial production of the units . For

example, switchguards we re installed on approximately 250 units to prevent inadvert-

ent switch actuations, and shatterproof len ses were installed to protect personnel fr om

flying gla ss and to protect readout devices from damage.

C h e c k o u t R e q u i r e m e n t s

Six factor y tes t stands we re planned to support s epa rat e command module and

se rvi ce module checkouts. Subsequent analysis verified the feasibility of performing

these checkouts in a mated configuration using integrated stand s. Consequently, the

number of te st stands req uired wa s reduced to four (fig. 8 ) .

Flex ib le Hoses

During initial site activation,hardlines could not be routed to the GSEbecause location was not defined. Hard-

lines we re routed to bulkhead interfac es,

and flexible hose s were used to connect

bulkhead interface, GSE, and spacecraft

fittings (fig. 9). The us e of hose s in

this manner result ed in the following

problems.

1. Internal flaking caused con-

tamination of the fluid.

2 . The requirement for periodic

proof-pressure testing incurre d addi-

tional time and cost.

3 . The u se of i ncorre ctly

pressur e-rated hoses created safety

hazards.

station. 4. The interchange of incompat-

ible hoses among fluid sourc es cr eated

sys tem contamination and hazardous

conditions.

Figure 8. - Integrated checkout

Becaus e of these problem s, many hoses were replaced with hardli nes (fig. lo) .

9



(a) Flexible hose at console.

Figure 9..

(b) Flexible hose routing.

F1 xibl e hose s .

(a) Console installation.

Figure 10. - Hardlines.

(b) Equipment routing.

10



E l e c t r ic a l C o n n e c t o r s

Many testing hour s wer e lost because of impr oper p roce dure s in the mating and

demating of elect ric al connectors. To avoid this prob lem, a mate and demate connec-

tor checklist was implemented. Connections require d for specific test s wer e con-

trolled by installing plastic connector locks that were verified by quality control.

E l e c t r i c a l P r o b l e m s

A spacecraf t system/GSE asse ssme nt revealed that cur ren t and voltage levels

in exc ess of spac ecra ft specification limit s could re sult i f elec tric al GSE was improp-

erly adjusted or operated o r i f a GSE cont rol component fai led. Res ult s of analys is

indicated that such a condition would overstress spacecraft components and could go

undetected in subsequent test s. Voltage- and current- limiting de vices (such as c i r -

cuit breakers, fuses, diodes, and resis tors ) were added to co rr ec t thi s condition.

Over pressu e P r ob le m s

Many GSE relief valves were not s ized properly to c a r ry the quantity of fluid

that would be avai lable i f an upstream regulator failed. A regulato r fa ilur e would

allow pressures at the spacecraft interface to exceed specification limi ts. Ther efor e,

properly sized relief valves wer e added.

GROUND POWER SYSTEM

During the conceptual stages of the Apollo GSE design, di re ct current (dc) was

selected a s the type of pr im ar y power sourc e to be used f or cont rol and monitor func-

tions. Thi s selection was influenced by three important facto rs that greatly simpli-

fie d the detailed design of the GSE end item s. Fi rs t, many commercially available

elec tric al components wer e designed to use 28 volts dc. Second, dc control signals

did not req ui re the complex routing, grounding, and shielding techniques that were

required by alternating-current (ac) control signals. Thir d, and most important , the

GSE dc control system w a s more compatible with the spacec raft because the prima ry

Spacecraft power sour ce was also dc.

The u se of 60- and 400-hertz ac power w a s limited to pumps, heaters, motors,

lighting, and ac-to-dc conversion equipment (fig. 11). This arrangement resulted in

cheaper , commerci ally available hardware and simplified design.

11



. Figure 11. - Alternating-current to direct-current

converter.

D i r e c t - C u r r e n t G r o u n d P o w er S y st em

"I

Direct-current power was provided by solid-state power supplies that had vari-able outputs as great as 40 volts a t the launch pad (fig. 12). Each power supply had anassociated backup system that consisted of ba tte rie s, battery ch arg er s, and, f or ini-tial control voltages, a sma ll dc power supply that was powered by a c. The powersupplies were cent rally located at the base of the mobile launcher and a t the base ofthe mobile service struct ure . Power was distributed to the spacecraf t and the GSE

1

through large ( 3 5 0 to 500 MCM ) copper cables. Power was provided to acceptancecheckout equipment (ref. l ) , command module buses, lunar module buses, and otherGSE that supported launch operations and checkout. Six power supplie s wer e locatedon each mobile launcher, and two were located on the mobile service structure.Control and monitor functions we re integrated into a syst em that interfaced with theremote-control stations.

A l t e r n a t i n g - C u r r e n t G r o u n d P ow e r S y st em

Because 400-hertz ac power was not available as a facility source, GSE unitsthat would supply this power at the launch pads wer e manufactured. Initially, onlythree types of GSE requir ed 400-hertz power. Two types wer e lat er deleted, but theus e of 400-hertz power was continued for the t hird type because of weight res tri cti onsimposed on the mobile launcher at the spacecr aft level. The weight restri cti ons wereremoved later, and a conversion to 60-hertz power was authorized on the remainingGSE model a s a cost tradeoff instead of modifying the 400-hertz power supplies thathad undergone excessive failures.

'MCM = cross-sectional area given in thousands of circula r mill imeters.

12



\\ It

CSM BUS B P W R !

D A W E D C i i D D l Y r REMOTE VOLTAGE ADJ I

t.

-LEMm . * . .. SPACECRA

Figure 12 . - Direct-current power supplies.

SPECIAL TESTEQUIPMENT

The need for factory test equipment that could be produced expeditiously andwithout for mal GSE contro ls resu lted i n the fabrication of special te st equipment.The equipment was facto ry built, and good commerci al standards and availableoff-the-shelf components wer e used. Special test equipment was used on an interi mbas is to fulfill the need fo r GSE created by expanded te st requirements. The hard-ware w as approved as "one of a kind, '' and no sp ar es were provided. Some specialtest equipment was built to GSE documentation standards and was identified later asGSE for u s e on subsequent vehicles.

Occasionally, the lack of adequate controls a t the fact ori es allowed fabricationof hardwar e fro m sketches, layouts, and load diagrams. The hardware configurationwas not forma lly documented. This lack of documentation made the hardware config-

ura tion unacceptable fo r follow-on te st s and made data corr elation difficult.

13



CLEA NLINES S AND EN Vl RONMENTAL CONTROL

To achieve reliable perf orm ance of the Apollo sy ste m, all operations that involvedvehic le buildup, testing, and shipping had to be perfor med in a cleanroom environment.The GSE fluid- sys tems cleanliness was controlled by a specification that defined allow-able contamination levels.

E n v i r o n m e n t a l l y C o n t r o l l e d A re a s

After the basic vehicle str uc tur e was assem bled and cleaned, struct ural clean-liness during subsystem installation and test operations could be maintained only inan environmentally controlled area in which personnel wore cleanroom g arm ents(fig. 13). Further controls wer e exercis ed by logging removable items brought into

the spacecraft, by limiting access tothe spacecraft, and by maintaining posi -tive pr es su re in the spacecraft crewstation and in all pressure vessels .

FIu i d s

The spacecraft fluid-systemsdesign specification required that thesystem be free of particles larger than100 mic rom ete rs . The fluid-servicingGSE w a s designed and maintained toexceed this stringent cleanliness require-ment. Partic ulate contamination wasa constant probl em because of the neces-

sit y of using flexible ho se s, which con-taminated the fluid, and the inability tope rfo rm in-place cleaning because ofsy st em design. The contamination prob-le m was minimized by installing fil te rsat the vehicle interface.

AUT OMAT ION

Figure 13. - Cleanroom garments.13ecause of de iianding Apollo

schedules, spacecraft test activitieshad to be accomplished expeditiously within the a ccur acy ra nge s nec es sar y to ens uremaximum safety and mission succ ess , Spacecraft subsyst ems wer e verified simul-taneously and i n parall el with some manufacturing opera tions. Many checkout andservic ing operations were automated to reduce test time and to meet requiredschedules.

14



Automated Checkout

The electrical checkout and fluid- serv icing functions f m the Apollo spacecr aftsubsystems were commanded and monitored from a remotely located computerizedcontro l roo m (fig. 1). Within this control room, computer ro utines we re used to applyspacecraft subsystem test stimuli. Related spacec raft resp onse s wer e displayed onsubsyste m consoles and monitored for out-of-tolerance conditions. Subroutines we re

use d fo r fault isolation tes ts during troubleshooting operations. The automation offactory test and launch control sequences was instrumental in achieving a well coor-dinated and expeditious spacecraft checkout and launch operation (ref. 1).

Automated Servic ing

Safety and operational considerations dictated t hat the fluid- servicin g equipmentbe designed for both local and rem ote operation. Control panels for local operationare shown in fig ure s 14 and 15.

Figure 14. - Fuel control panels.

When the prog ram entered theoperational phase, it became evidentthat total remote operation of the ser-vicing functions was not practicalbec ause the majority of the effort was

expended in prep arin g for the test.Important operations that were unsuit-able fo r automation wer e the installa-tion of filters, the connection ofequipment to the spacecraft, the pe r-fo rm an ce of leak checks, the verifica-tion of proper GSE setup, and the

Figure 15. - Fuel control panel details.

15



sampling of fluids. By rescheduling ta sk s during nonhazardous operations and by

changing some of the requi rem ent s, mos t of the serv icing w a s accomplished locally,

and the parameters were displayed both locally and remotely in the computerized

control room.

The increas e i n acceptance checkout equipment (ACE) control r oom displays

pro gre sse d to the point where the memory capacity of the ACE computer had very

little growth potential. Thi s limitation in ACE memory would result i n data beingprovided to the test o pera tors on a delayed basis by posttest data reduction, which

would be especially unfeasible when data analysis from one test was required before

the st a r t of the next test. In 1968, the ACE memory capacity was inc rea sed by

24 000 memory bi ts to per mit planned operations and allow fo r future growth in ACE

control room displays.

COMMON-USE EQUl PMENT

The use of s im ila r spacecraft hardware , propellants, and checkout techniques

made the sha ring of GSE poss ible. The shar ing concept eliminated duplication of equip-ment design and fabrication by sepa rat e cont rac tor s when performin g sim ila r functions.

Because the operating cha rac ter ist ics and location of the common-use GSE were not

identical, t h e following three equipment categories were established.

1. Category A- 1 : Equipment in this category was unmodified hardware that

The developing cont ract orulfilled the requir emen ts of mor e than one contr actor .

operated the hardware and maintained configuration control.

2. Category A- 2 : Equipment in this category w a s the same as category A-1

equipment except that the using contr acto r operated i t.

by the developing cont racto r and installed by the us e r .

Modifications were fabricated

3.

cations.

using contractor had total responsibility for the hardware.

Category A-3: Equipment in this category was designed for multiple appli-

Modifications to the original designs were necessary for specific use s. The

MANAGEMENT OF GROUND-SUPPORT EQUIPMENT

AND SITE READINESS

Projec t management of GSE w a s not limited to design, fabrication, and manu-

facturing schedule reviews. Proj ec t management al so encompassed the GSE allocation,

priority establishment, integration, installation, and verification a t each manufacturing,

test, and launch site.

Because of stringent Apollo schedules, GSE was manufac tured concurrently with

test- and launch-site construction. Thus, a GSE/site-activation organization had to

be formed quite early in the prog ram. Specialists were s elect ed to manage the site

activation at all manufacturing, test, and launch facilities. A composite evaluation

was made of problems common to al l si te s (such as fluid cleanliness ). The status of

16



site readines s was a ss es se d by the NASA Lyndon B. Johnson Space Center (JSC)

(for merly the Manned Spacecraft Center (MSC)) i n monthly management reviewmeetings . When launch, vehicle , and tes t schedules changed, specific "need dates"

for GSE end it ems changed. These changes were reflected in the GSE production

plans and delivery schedules.

After initial s it e activation, sit e readiness for follow-on vehicles was determinedin an MSC and contractor review meeting conducted just before vehicle ar riv al for tes t

o r launch. This effort included a physical inspection of the s i te s and associated GSE.

A l l pertinent documentation, such as modification-installation stat us repor ts, open

engineering or de rs , quality and reliability control rec ord s, and interfac e control docu-

ment revisions, was reviewed in detail for open work,

M A 1NTENANCE AND OVERH AUL

Readiness of GSE was ensured by periodic calib rati on, overhaul , o r component

replacement. Overhaul candidates were primaril y i n the field of serv icin g equipment.

In the Apollo Progr am, serv icin g equipment had backup or redundant units that enabled

the perf ormance of o rde rly, timely overhauls with no launch cons traints.

Contracto r proposals fo r GSE overhauls were based on usage, age, o r failure

history. Thes e proposals were evaluated to determine the extent of overhaul. The

following considerations were included.

1. Use and environment of equipment

2. Expense of overhau l compared with expense of end-item replacement

3 . Availability of backup unit s to support pr im e uni ts

4. Availability of spares

5 . Review of the fa ilu re history

6 . Periodic repl acement of components already authorized in age/life component-

replaceme nt cri ter ia and in routine preventive maintenance schedules

RECOMMENDATIONS AND CONCLUSIONS

Recommenda t ion s

The following mate rial is presented primarily as recommendations for use in

future programs.

Design standardization. - Design standardization encompassed the use of stand-

a r d cables and patchable connectors that provided interchangeability and vers atil ity

among the ground-support-equipment units so that vehicle requirem ent changes could

17



be accomplished. Standardization of calibration data and som e computer pro gr am s

permitted a close co rrelation of tes t data fro m the facto ry to the launch pad.

Ground- support equipment was standardized to reduce the number of diff eren t units ,

to reduce the ground- support-equipment manufacturing tim e, and to reduce the

ground-support-equipment and spacecraft test time. Portability was a prima ry con-

sideration when fluid-servicing and test h ardware wer e standardized.

Design inadequacies. - Design inadequacies may be limited i f the most seve rerequirement is selected a s a design base. This s election would have the net effect of

limiting the number of design s, reducing spa re s, providing for interchange of hard-

ware between sites, limiting the total end items, and developing standard operating

techniques.

The use of flexible hoses as permanent installations should be avoided. How-

ev er , hoses a r e valuable for temporar y connections and for us e where cleanliness isnot a prime consideration.

Controls should be instituted for mating o r demating electr ical connectors.

Proper connections can be maintained i f destroy-to-remove plastic connector locks

are used. Another considera tion is an electrical series circuit that is routed throughall required connections and illuminates an indicator light.

On variable electr ica l power supplies, devic es should be provided to limit output

to the allowable system voltages or currents (or both). Groundsu ppor t equipment

should be designed for maintainability and fo r e as e of component replacement.

Capacity requir emen ts should be evaluated, and allowance should be made fo r

growth or expansion of sy ste m requ ireme nts. This consideration should be refl ected

in design standards applicable to new procurements.

Safety devices, such a s switchguards and safety glass on me ter s and gages,

should be incorporated into the original design. These device s could be incorporated

initially at a fraction of the cost for lat er addition. Periodic syste m analysis should

be performed on each major ground-support-equipment sys tem to ens ure that all pro-

tective devices a r e properly sized to protect the sp acec raft.

Ground power system. - The use of 28-volt di rec t-c urr ent power f o r ground

instrumentation and control is a good design approach . The power distr ibuti on

sou rce can be simplified by routing 60-hertz power to eac h usage area and then con-

verting it to dire ct curren t. Facility-supplied power require ments should be defined

early to establish the input-power design approach for ground-support equipment.

When 400-hertz power is required, it should be supplied fr om a facility s ystem .

The distribution system should be the same as that recommende d in routing 60-hertz

power.

Special test equipment. - Two cla ss es of special t es t equipment should be estab-

lished.

o r provides power, instrumentation, and servici ng functions.

requ ire formal configuration control. Cla ss 2 te st equipment should consist Of all

Class 1 should consist of equipment that inte rfac es directly with the spa cecr aft

Class 1 equipment should

18



other equipment (such as diagnostic test tools, special manufacturing devices, and

workstends). Class 2 equipment would r equ ire minimum configuration control at the

using si te; changes could be authorized by the resident manager.

Cleanliness and environmental control. - The vehicle cleanliness req uirem ents

should be established and thoroughly justified early i n the design phase because ground-

support-equipment costs inc rea se geometrically as cleanliness requirements becomemore stringent. During a ground-support-equipment syst em buildup, accep table

cleanliness must be verified as each component is installed. The final fluid sampl e

must be taken at the ground-support-equipment/vehicle nterface. A certified, cleanfilter should then be installed downstream of the l as t sample point before serv icing.

This insta llation eliminated the need for numerous expensive quick-disconnect fittings

used solely for sampling.

Hardware that ha s environmental requirements should be cleaned to an estab-

lished level early in it s construction, and this cleanliness should be maintained until

completion. Personnel should be given cleanliness instruction, and the required

cleanliness levels should be posted. Assembly areas should be designed and built

as specified’clean areas during initial construction.

Automation. - Decisions to determine the ground sys tem s to be automated. must

be based on a comprehens ive review of projected pro gra m miles tones . Automation

is recommended when extensive and complex tes t and launch operations, such .as those

encountered during the Apollo Pr og ra m, must be accomplished within a limited time

f ra me ; however, the costs of automation must be carefully weighed against those

requi red to pe rfor m relatively simple mechanical task s manually (such as costs asso-

ciated with Apollo fluid se rvic ing).

Common-use equipment. - The common-use concept should be considered fo r

projects that involve more than one contractor when identical or simila r requirements

exist . Contractor capabilities must be evaluated to selec t a hardware developer thatis bes t suited to provide specific ite ms of common-use equipment.

should include manpower loading, manufacturing capabilities, procurem ent proc edu res ,

and scheduled work-load considerations.

This evaluation

Management of ground-support equipment and site readiness. - Ground- support

equipment site- activation schedules must be coordinated with manufacturing and

cons truct ion activ ities and alined with expected facility-occupancy dates . An automatic

schedule-adjustment procedure should be available to compensate for vehicle schedule

changes,

requirements (such as size, access, lighting, ventilation, air conditioning, and power

sour ces) keep pace with tes t-a rti cle and checkout-requirement changes. Basic facilityint erf ace definitions should be provided early in the progr am. Adherence to interface

contr ol documents should be enforced rigidly.

Periodic facility technical evaluations should be conducted to ensure that basic

Vehicle checkout requi rem ent s should be integrated with facility and ground-

support-equipment support requirements to optimize checkout flow, to reduce total

time , and to minimize equipment requirements. Vehicle/ground- support- equipment

integrated schematics should be required for use in troubleshooting and normal test

operations. These documents must be updated regularly.

19



Maintenance and overhaul. - Preventive maintenance should be performed on aperiodic basis. A l l contra ctors and vendors should be required to deliver preventive

maintenance procedures and age/life component-replacement data with the end ite ms .

Initial procurement of these data is more economical than obtaining them la te r. When

possi ble, overhauls should be perfo rmed in conjunction with ma jor modifications.

Conclusions

Overa ll, the Apollo ground-support equipment perfo rmed satisf actor ily.

Although problems were encountered in ground-support-equipment operation because

of design inadequacies, mat er ia l and equipment incompatibil ities, or manufacturing

flaws, no major personnel injuries o r test/launch delays were attributed to the

ground- support equipment during the 8 ye ar s of Apollo Pr og ra m support.

Lyndon B. Johnson Space Cente r

National Aeronautics and Space AdministrationHouston, Texas, September 25, 1974

9 14- 0-00- 0- 2

REFERENCE

1. Burtzlaff, I . J . : Apollo Experience Report - Acceptance Checkout Equipment

for the Apollo Spacecraf t. NASA TN D-6736 , 1972.

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