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40 D. ÖZTÜRK and H. AKYILDIZ

as process effect and product effect when applied Process FMEAs. However, article emphasizes
on Design FMEA for rotor swing stabilizer.

Occurrence is a ranking number related with the probability that the failure mode and cause will
be present in the item being analyzed [7]. If the team applies the process FMEAs on the product,
production stage should be considered while determination of occurrence. Occurrence ranking
number is a relative value instead of absolute value, detected regardless of severity or likelihood
of detection.

Detection is a ranking number related with the greatest control from the list of detection-type
controls, based on the criteria from the detection scale [7]. Likelihood of detection also has
relative ranking in a way that is specified with no regard to the severity and likelihood of
occurrence.

Figure 7. Flow diagram of FMEA.

Following to explanation of FTC and FMEA, in order to apply the methodical procedure on
rotor swing stabilizer further statement is needed. In this article design FMEA is applied
according to design requirements (see Appendix A), functions (see Appendix B), and
components (see Appendix C) of the rotor swing stabilizer. The most important output is the
risk consequences, and also severity, occurrence and detection values are detected to calculate
RPN. Moreover, effects of potential failures can be reduced in design stage of the system due to
the prioritization of risk consequences.

6. Conclusion

A technical review and bibliography listing on the historical in failure mode and effect analysis
(FMEA) and fault tolerant control systems (FTC) have been submitted in this article. Within the
scope of article, a simple design of a fault tolerant control system adapted to a smart rotor swing
system based upon design FMEA methodology. After a brief description of rotor swing
stabilizer and its working principle, a fault and risk analysis has been performed and some of
applicable actions have been submitted. First of all, basic block scheme and fault diagram of the
system were presented. After that, customer requirements were identified to invert them to
design requirements. Failure modes of design requirements were determined according to four
categories of absence, incompleteness, incorrectness, and improper occurrence. Consequently,
effect analysis and severities were found. According to the requirements, functions were listed
and same process steps were implemented. Finally, component failure modes and risk priority
numbers were detected. The reason for choosing the design FMEA to explore the possibility of
product malfunctions in the system was that there is not enough information and academic

GiDB|DERGi Sayı 7, 2016