CRITICALITY POTENTIAL EFFECT OF FAILURE

1 Loss of l i f e o r vehicle.²² Rogers Commission Report, Volume I, p. 199. Loss of mi ssi on.³³ NASA, "Report to the President Actions to Implement the Recommendations of the Presi- dential Commission on the Space Shuttle Challenger Accident," July 14, 1986. (Hereafter r e ferred to as NASA Response to Rogers Commission.) All others. 1R Redundant hardware element, a1 1 of which I f f a i l e d , could cause l o s s . of l i f e or vehicle. 2R Redundant hardware element, a1 1 o f which i f f a i l e d , could cause loss o f m i ssi on.

NOTE: See Appendix 8. paragraph 3.1.1, Ground Rules, sub-paragraphs 1 and 2. 8. Single Failure Point (SFPI - i s a s i n g l e item of hardware. t h e f a i l u r e of which would lead d i r e c t l y t o l o s s of l i f e , vehicle, br mission. Where safety considerations d i c t a t e t h a t abort be i n i t i a t e d when a redundant ftem f a i l s . t h a t item i s a l s o considered a single f a i l u r e point.

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Functional Mode - I d e n t i f i e s each f u n c t i o n t o be performed by t h e item being analyzed. .~ 10. - Multiple Order F a i l u r e d e s c r i b e s t h e f a i l u r e due t o a s i n g l e cause o r e v e n t of a l l u n i t s which perform a necessary ( c r i t i c a l ) function.

C r i t i c a l Item a s i n g l e f a i l u r e p o i n t and/or a redundant element i n a l i f e o r mission-essential a p p l i c a t i o n where: a. Redundant elements a r e not capable of checkout during t h e nonnal ground turnaround sequence. b. Loss of a redundant element i s n o t r e a d i l y d e t e c t a b l e -in f l i g h t . c. A l l redundant elements can be lost by a s i n g l e c r e d i b l e cause o r event such as contamination o r explosion.

-- K i t For t h e purposes o f t h i s desk i n s t r u c t i o n . a k i t i s defined a s a temporary a d d i t i o n o r modiffcation t o t h e O r b i t e r o r i t s subsystems t o s a t i s f y unique requirements f o r a s p e c i f i c mission.

Post Landing Safing OperaCons For t h e purposes o f t h i s desk instruc: t i o n . p o s t landing s a f i n g o p e r a t i o n s a r e defined a s t h o s e a c t i v i t i e s performed a f t e r landing t o prepare t h e O r b i t e r f o r hangar operations. This includes t h e deservice and d r a i n i n g o f a l l hazardous f l u i d s , s a f i n g of unused ordnance. a p p l i c a t l o n o f ground power and cooling, removal of p o t e n t i a l l y hazardous components, pods and payloads, purging and vent1 ng o f gases and t h e i n s t a l l a t i o n of p r o t e c t i v e covers.

Prelaunch Operations Prelaunch o p e r a t i o n s f o r propulsion subsystems i s defined a s beginning with p r o p e l l a n t loading f o r each s p e c i f i c subsystem. For a1 1 o t h e r subsystems prelaunch o p e r a t i o n s comnence w i t h start of main engine conditioning. -c

¶3.0 FMEAKIL PREPARATIOl

¶FMEA's will be prepared j o i n t l y by t h e responsible designer and t h e assigned R e l i a b i l i t y Subsystem Analyst (RSA) i n accordance with t h e a t t a c h e 4 format, Appendix 0 (Ground Rules and C r i t e r i a ) and a s shown i n FIGURE 1. Safety. o t h e r engineering d i s c l p l i n e s , and t e c h n i c a l support f u n c t i o n s ( s e e EOM D i r e c t i v e

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¶70 2-6.3.1) w i l l provlde support as required. Where the FMEA deviates f r o m the instructions and ground rules contained herein, approprlate notation w i l l be Included w i t h i n the 'Ground Rules and Crlteria' o f the FMEA preface.

¶3.1 SCH€DULE

¶R e l i a b i l i t y , i n coordination with Design, w i l l define the schedule and depth of d e t a i l for each FMEA t o be prepared f o r the Orbiter i n support o f contractual mqulrements. and issue an FMEA schedule.

3.2 CONTENT

¶Each subsystem FMEA/CIL shall be prefaced by the following Information. sequenced as Indicated:

1 .OINTRODUCTION 2.0 QUALITATIVE RELIABILTY S W R Y 2.1 SUBSYSTEM DESCRIPTION AND EFFECTIVE DATE 2.2 SIGNIFICANT UNDEFINED DESIGN AREAS

2.3 CRITICAL lfEMs S U Y 3-0 GROUND RULES AN0 CRITERIA .

4.0 DISPLAYS AND CONTROLS INDEX 5.0 LIST OF REFERENCE DOCUMENTS 6.0 SCHEEIATICS

¶The backup infonnation. including rationale and anaylses involved i n assessing f a f l u r e modes and t h e i r effects, generally I s not included i n the f i n a l FMEA and CIL package. Where such infonnatlon e x i i t s i n the form o f notes, calculations, IL's, references and other similar material, i t w i l l be retained by the responsible RSA. Should the RSA be reassigned, he will t u r n over the material t o h i s supervi sor.