Reports that Matter

Investigation of the Challenger Accident

4.2 REVISIONS & SUBMITTALS

Section 45 of 55

4.2 REVISIONS & SUBMITTALS

  1. Revisions t o the FMEA w i l l be made a s follows: a. N e w Data: ( 1 ) To identify new components or f a i l u r e modes. use the data entry sheets and follow the instruction given in section 4.1. (2) To add information t o a component o r f a i l u r e mode record. e i t h e r a blank data sheet o r the appropriate page of the data p r i n t o u t working copy nay be used. - ( a ) Data Entry Sheets Usfng a blank data sheet, c i r c l e "R' [Revise) on the "Data Identifier" line (01. FIGURE 4 o r 5 ) and enter the correct subsystem/canponent/(failure mode) I D number t o identify t h e record t o which the information is t o be added. F i l l i n complete blocks of information t o be added (e.g., Disposition b l o c k ) . and s u b m i t f o r keypunching.

(b) Data P r i n t o u t - Circle "R' (Revise) on t h e "Data Identifier" l i n e (01, FIGURES 6 and 7) of the record t o which new information is t o be added. Using a colored pen or pencil, enter t h e information i n t h e appropriate blocks and submit f o r keypunch.

b. Data Entry Change: Circle t h e "R" (Revise) on the "Data Idenifier" line (01. FIGURE 4 or 5 ) and e i t h e r "red-llne" the appropriate sheet of the data printout o r re-enter t h e data a s i t should appear, u s i n g the appropriate data entry sheet a s described i n section 4.2, paragraph ( a ) Data Entry Sheets. To clear the "3" f i e l d of any remaining unwanted Information, asterisk (*) the blank l i n e s w i t h i n t h e -.- block on the master record and supporting record work sheets.

C. Data Deletion: (1) To delete data, c i r c l e the ' R" on the "Data Identifier" l i n e (01. FIGURE 6 or 7 ) of the appropriate data p r i n t o u t sheet. cross O u t the entry t o be deleted w i t h a colored pen O r pencil

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DI NO. 100-26 Page of 34 and submit f o r keypunching. If a blank data sheet is used. enter an asterisk (*) f n the block which corresponds t o the entry t o be deleted.

( 2 ) To delete the entire record (i.e.. a l l data pertaining t o a particular failure mode o r component) and a l l related entries, circle the "D" (Delete) on the appropriate sheets of the data p r i n t o u t . Again, f i l l i n g out the data i d e n t i f i e r t i n e of a blank data sheet will accomplish the same purpose. A l l information pertaining t o a particular component o r f a i l u r e mode will be deleted.

d. :- To change a data identifier ( L V l ,2 Rogers Commission Report, Volume I, p. 199. o bid., Chart SRB-4. 2 1 Larry Mulloy, NASA, Marshall Space Fli ht Center, "STS-51L Level I1 Flight Readiness Review,'' January 14,1986. See Appendix VIII-g. 2 2 Discussion with Allan McDonald, September 4, 1986. Z3 Rogers Commission Report, Volume 11. See Chart 15 (p. H-10) and Chart 19 (p. H-12). s Ibid., Chart 30 (p. H-18). o r 3). i t is necessary t o delete the entire record under the old number and re-entrer (add) under a new number. The B999/revision data on computer reports is autmated and p r i n t s the date of the l a t e s t update or revision.

e. Identification of Revisions/Changes: Identify each line changed w i t h a vertical black bar on the l e f t - hand margin of the page.

FMEAKIL Submittal

a. Critical Items List (CIL) Updates will include the following: (1 ) Any new CIL I tens ( 2 ) Updates t o existing items having technical changes affecting the following sections: -- - ( a ) function ( b ) f a i l u r e mode ( c ) f a i l u r e effects (d) c r i t i c a l i t y ( e ) abort c r i t i c a l cmponents ( f ) f a f l u r e detectability (redundancy screen) .' Other changes w i l l be incorporated when pages are s u h i t t e d f o r the above reasons.

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b. FMEA's Updates o f the FMEA's will be a t six month intervals linked t o nearest scheduled CIL FRR publication. Only those changes related t o the CIL submittals (5 above) and other technical changes wtll be submitted.

4.3 I

MPLEMENTATI

O N GROUND RULES (See a ls o Appendix B - Ground Rules and Criteria)

4.3.1 HARDWARE CRITICALITY DETERMINATION

Hardware c r i t i c a l i t y will be determined by t h e categorization o f the singular effect of the identified fa ilure mode on the subsystern/vehicle (See FIGURE 10). FIGURE 8 i l l u s t r a t e s the analytical logic f o r c r i t i c a l i t y detennination I o f a l l functional hardware.

  1. Rellability Engineering ide ntifie s hardware where i f redundancy f a i l s the e ffect would be c r i t i c a l . -
  1. Reliability and Design Engineering jointly identify those equipments '

w i t h (single point) c r i t i c a l i t y 1 or 2 fa ilure modes. Those equipments that. are not c r l t i c a l i t y 1 because they incorporate redundancy are then screened further, a s described i n paragraph 4.1.n. and appropriate entries made i n the FMEA d a d sheet.

  • NOTE: The C ri t i ca lity of instrumentation and t e s t ports will be assessed according t o the ir function. Test ports, when capped, shall be treated as a structural part of the ccmponent and not be considered further. Where i n s t m e n t a t i o n (e.g., pressure transducer) penetrates the wall of a component or l i n e and structural f a i l u r e of the j o i n t would result i n gross leakage, the fa ilure mode shall be considered a s a fa i l u re of t h e component or line. The c r i t i c a l i t y of the instrument- ation. therefore. would not be affected i n such instances.
  1. The c r i t i c a l i t y of those systems which are t o be used only i n the event of an emergency shall be established s t r i c t l y on the basis of dire c t fa i l u re effect on crew. vehicle, o r mission, regardless of t h e number of prior fai l ures which must occur before the use of t h e system i s required.

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DI NO. 100-26 Page 23 of 34 A l l other backup or standby equipment (e.g.. re lie f valves. cross-feed valves, etc.) shall 'assigned c r l t i c a l i t y In the n o m l manner.

4.3.2 FUNCTIONAL CRITICALITY DEERMINATION

Functional c r l t l c a l i t y will be determined by the categorlzation o f the e f f e c t on the subsystemlvehlcle o f los s o f a l l redundancy ( l l k e o r unlike) f o r the identified fa l l ure mode (See FIGURE 10). FIGURE 8 Illus tra te s t h e analytical ' logic f o r c r l t i c a l l t y determinatlon o f a l l functlonal hardware.

  1. Reliability Engineering ide ntifie s hardware i f a l l l i k e or unlike redundancy f a l l s the e ffe c t vould be c r l t i c a l .
  1. Reliability and Design Englneering jointly identify those equipments with c r i t i c a l l t y 1 R or 2R f a l l u r e modes.

4.3.3 CIL CONTENT CRITERIA

  1. The following classification of fa llure modes will be entered In the CIL: a. All functlonalhardware c r i t i c a l i t y category I l l ' s . 212's. and . 1R2's. b. A11 c r i t i c a l i t y category 1R3's and ZR3's t h a t f a i l one or more redundancy screens. c. All faflure modes t h a t +ccine c r i t i c a l i t y category 1/1 durlng Intact abort.
  1. CIL Se6tion 12.0 - Critical Items List orbite r modifications t o support speclal m i sslons :

This sectlon of the Critical Items List contains those c r i t i c a l Items asscciated with Orbiter subsystems t h a t have been added t o or modified by Orbiter Mlssion Klts t o support special missions. These CIL items will only apply t o specific vehicle missions as noted i h t h i s speclfic CIL subsectlon.

T h i s CIL section contains the single fa ilure paints and c r l t l c a l i t y 1~ R CIL items identifled by the Failure Mode Effects Analysis IFMEA) and 2 conducted on t h e Orbiter subsystems tha t have been added t o or modified

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01 NO. 100-26 Page 24 of 34 t o support 'special mission application. These vehicle changes are Identlfied by individual Mission Klts which are Installed specifically f o r these special missions and wuld be removed when t h C mission objectives have been achieved. Each vehicle change is identifled by a Master Change Record (MCR) and I s referenced i n the applicable FMU.

Each c r i t i c a l f a i l u r e mode identified in the vehicle modification ,. section is categorized on a separate Critical Items List form which

Includes the f a i l u r e causes, effects, and rationale f o r retentlon. CIL dispositions and rationale are contained on individual CIL sheets and those t h a t are generally applicable t o a l l components are contained i n Section 3.0.

A c r i t l c a l Items l i s t suinnary I s Included for each maor vehicle modification. Additions w i l l be made t o t h i s CIL section t o maintain t h i s document current with t h e vehicle f l i g h t configuration. CIL page revisions are Indicated by revision date.

  • NOTE: Prfor t o each CIL submittal, notify t h e CIL coordinator of any input t o CIL Section 12.0.