Page 42 - 07

FAULT TOLERANT CONTROL OF ROTOR SWING 39
STABILIZER SYSTEM USING FMEA METHOD

analyzes product designs or manufacturing processes, early in the product development process.
Its objective is finding and correcting weaknesses before the product gets into the hands of the
customer.

There are at least four recommended outline specifications that must be comprehended to follow
FMEA methodology [8].

 The whole of problems are not the identical. That is the main notion in the FMEA
methodology. Problems should be recognized according to their precedence.

 The customer must be known before the implementation of FMEA. The meaning of
customer is thought of as the end user in general. However, a customer is the following
process along with a service operation. As a matter of fact customer may be operation
itself in some instances. Deciding how the customer identifies has a significant role in
FMEA. For instance, customer is the end user in the design FMEA while next operation
in the process is the customer in process FMEA.

 It is an obligatory decision that the function, purpose, and target must be known.
 One must be prevention oriented. The working of application an FMEA will be constant

if not continuous progression is the constraining for FMEA. Customer satisfaction
and/or market necessities should be the priority.

Failure Mode and Effects Analysis is a methodology designed to:
 Describe and properly understand possible failure modes and their reasons, and the
impacts of failure on the system or final consumer, for a given product or process.
 Estimate the risk related with the defined failure modes, effects, causes, and prioritize
problems for corrective effect.
 Describe and implement corrective actions about the most critical concerns.
 Reduce the loss of product performance to minimum
 Enhance test and verification plans in System or Design FMEAs
 Enhance process control plans in Process FMEAs
 Apprise the situation about the product design changes or manufacture process changes
 Classify important product or process characteristics
 Improve preventive maintenance plans for in-service machinery and equipment
 Improve related diagnosis methods

5.1 Risk Priority Number

The term risk priority number (RPN) is numerical ranking of the risk on each possible failure
mode and calculated with severity, occurrence, and detection [7].

RPN = Severity rating x Occurrence rating x Detection rating

RPN ranges from 1 to 1000. Engineers and designers should place importance to the failure
mode which takes the highest value of RPN firstly. Then there will be some actions to correct
the failure mode and RPN number will be changed, see Figure 7.

Severity is the one of the multiplier of the risk priority number. There are ranking numbers from
1 to 10 to show how severely affected the product and/or process from failure mode in
accordance with selected FMEA type. Moreover severity has a feature to be relative ranking
regardless of occurrence and detection. It is important to separate the potential effects of failure

Sayı 7, 2016 GiDB|DERGi