Common Mode Analysis

All environmental deficiencies have been addressed In the common mode analysis... 

Explicitly, by adding as a specific failure mode (e.g. maintenance error) into the FT. The CCF typically originate from the Common Mode Analysis (CMA) (see Chapter 6), the Particular Risk Analysis (PRA) (see Chapter 7) or the Zonal Safety Analysis (ZS A) (see Chapter 8). 

Common Mode Analysis (CMA), which is the subject of this chapter ... 

Step 2 analyse each Common Mode Analysis vulnerability to IdentifyArerify independence criteria... 

Step 1b identify common mode vulnerabilities via the Common Mode Analysis checklist... 

The common cause analyses are performed. R R A N N Particular Risk Assessment (PRA) Common Mode Analysis (CMA) Zonal Safety Analysis (ZS A) 5.1.4 ... 

RTC A/DO-254 defines Functional Failure Path (FFP) as the specific set of interdependent circuits that could cause a particular anomalous behaviour in the hardware that implements the function or in the hardware that is dependent upon the function. FFP Analysis (FFPA) is used to iteratively decompose the hardware functions into a hierarchy of subfunction to determine if it will be possible to fulfil completely the objectives of RTCA/DO-254 for each subfunction. If the assurance lifecycle data available or expected to be available is complete, correct and acceptable per the RTCA/DO-254 objectives and guidance, then no further decomposition is necessary. If it is not, then decomposition continues until such a stage as the FFP feasibly maps to one of the Development Assurance methods (and associated data set) as described in the previous section. For FFPs that are not Levels A or B, their interrelationships with the Level A or B FFPs should be evaluated using an F-FMEA, common mode analysis or dependency diagram to ensure that the Level A and B FFPs cannot be adversely impacted by the FFPs which are not Level A or B. 

This step involves the Safety Engineer highlighting to the Test Pilot and/or the HF Specialist all failure conditions identified via techniques such as the Functional Hazard Analysis (FHA) (Chapter 3), Failure Modes and Effects Analysis (EMEA) (Chapter 5), Common Mode Analysis (CMA) (Chapter 6), Particular Risk Analysis (PRA) (Chapter 7) and Zonal Safety Analysis (ZSA) (Chapter 8). 

Common Cause Analysis Generic term encompassing zonal safety analysis, particular risk analysis and common mode analysis [RTCA/1X)-178B/ED-12B]. 

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