| 2.2.2-5-1 Ensure evidence for a clear method (work products describing methods) for identifying mission-ending failure situations and contributors covering mission phases and characteristics. |
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Each mission objective needs to be considered in the MCFA. The priority of the objective may influence the depth of analysis and/or exoneration methods. Any changes to the architecture, design, or implementation of the system must be reflected in the current MCFA. Mission objectives should be viewed from a mission execution perspective to determine the potential mission failures. These failures should be traced down to potential causes that may work singularly or in combination. Consideration should be given to organizational responsibilities and constraints to ensure TLYF effective results in requirement decomposition. Challenges should be recognized when different organizations may be responsible for Enterprise vs. a segment that restricts the ability to respond to perceived deficiencies. Mission characteristics can include any of the following: items, processes, transactions, parallel activities, interfaces that promote successful mission execution.
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NA
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016 (Section 4.3, MCFA); TLYF
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| 2.2.2-5-2 Ensure that for each mission-ending failure situation, there is a clear method and associated artifacts for identifying potential fault paths and contributors |
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Work products showing the what critical fault situations were analyzed is important. These may come in the form of fault trees and leaves. The leaves reveal the critical mission characteristics. Fault paths and contributors must be addressed and exonerated to reduce risk.
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AFMAN 63-119 A13.3.2
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016 (Section 4.3, MCFA); TLYF
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| 2.2.2-5-3 Ensure mission critical events and critical contributors have been developed or can be easily derived and decomposed from existing work products. |
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The first time / mission critical events list must include the first time and critical events for all mission phases and anomalous events. If the apparently same event has different behavior under two different sets of conditions, then it is treated as two different events. It is important that as the mission timeline (sequence of events) is decomposed it is clear how subsystems support lower level mission activities.
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NA
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016.
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| 2.2.2-5-4 Ensure evidence for a clear method for linking potential mission critical faults (paths and contributors) with an exoneration plan (I, A,D,T) |
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Each mission critical fault path must be exonerated by a LYF test and/or suitable analysis. A LYF test is preferable but program considerations may require an analysis for some or all aspects of the fault path.
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NA
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016; TLYF
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| 2.2.2-5-5 Ensure potential mission critical faults (paths and contributors) not exonerated by test are elevated to program risk-level and there are evident linkages between LYF test exceptions' risk evaluation and program risk management |
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Mission critical faults exonerated by analysis must be considered to be a program level risk since analysis does not have the same level of confidence and can only include factors known at the time of the analysis. Analysis does not include unknown interactions and must make assumptions about truth. LYF test exceptions deemed critical (exceptions that are tied to fault paths) need to be managed for risk.
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NA
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016; TLYF Process Assessments ATM-2015-04239 REV A; Mission Risk Assessment Instruction for APR and ASMR; TLYF
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| 2.2.2-5-6 Ensure clear method for evaluating the criticality of LYF test exceptions and for keeping record of the exoneration evidence for critical LYF test exceptions. |
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Wherever LYF tests deviate from the characteristics of mission operations is considered an exception. The effect LYF test exceptions must included in the analysis of the Critical Fault Risk.MCFA or some similar pre-operational analysis is necessary for evaluating LYF test exceptions.
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NA
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NA
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Test Like You Fly Process Guide for Space, Launch, and Ground Systems, TOR-2014-02537 Rev A, September 2016; TLYF Process Assessments ATM-2015-04239 REV A; TLYF
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