My Reading on ASQ CQA HB Part V Part 2

Part VH
Indication
If the undetected failure allows the system to remain in a safe / working state, a second failure situation should
be explored to determine whether or not an indication will be evident to all operators and what corrective action
they may or should take.
Indications to the operator should be described as follows:
• Normal. An indication that is evident to an operator when the system or equipment is operating normally.
• Abnormal. An indication that is evident to an operator when the system has malfunctioned or failed.
• Incorrect. An erroneous indication to an operator due to the malfunction or failure of an indicator (i.e.,
instruments, sensing devices, visual or audible warning devices, etc.).
PERFORM DETECTION COVERAGE ANALYSIS FOR TEST PROCESSES AND MONITORING (From
ARP4761 Standard):
This type of analysis is useful to determine how effective various test processes are at the detection of latent
and dormant faults. The method used to accomplish this involves an examination of the applicable failure
modes to determine whether or not their effects are detected, and to determine the percentage of failure rate
applicable to the failure modes which are detected. The possibility that the detection means may itself fail
latently should be accounted for in the coverage analysis as a limiting factor (i.e., coverage cannot be more
reliable than the detection means availability). Inclusion of the detection coverage in the FMEA can lead to each
individual failure that would have been one effect category now being a separate effect category due to the
detection coverage possibilities. Another way to include detection coverage is for the FTA to conservatively
assume that no holes in coverage due to latent failure in the detection method affect detection of all failures
assigned to the failure effect category of concern. The FMEA can be revised if necessary for those cases where
this conservative assumption does not allow the top event probability requirements to be met.
After these three basic steps the Risk level may be provided.
https://en.wikipedia.org/wiki/Failure_mode_and_effects_analysis
Charlie Chong/ Fion Zhang