ON CONDITION TASK Module 3 UNIT III HOW TO PERFORM RCM " Copyright 2002, Information Spectrum, Inc. All Rights Reserved."

Module Preview: IntroductionIntroduction Introduction Introduction Task Development Task Development Review and summary Review and summary ON CONDITION TASK

Module Objective: This module will provide information for developingandevaluating On Condition tasks: This module will provide information for developing and evaluating On Condition tasks: 1. Identify when it is appropriate to develop an On Condition task 2. Show how to develop an On Condition task for a given failure mode 3. Show how to determine an appropriate task interval for an On Condition task Introduction

ON CONDITION TASK DEVELOPMENT ON CONDITION TASK DEVELOPMENT ON CONDITION TASK

On Condition Task: Task Development Definition - A periodic or continuous inspection designed to detect a potential failure condition prior to functional failure If the inspection reveals a potential failure condition, corrective action must be taken If the inspection reveals a potential failure condition, corrective action must be taken If potential failure condition does not exist, nothing is done, item continues in service If potential failure condition does not exist, nothing is done, item continues in service ON CONDITION TASK

On Condition Task: On-condition task objective is to maximize the useful life of each piece of equipment by allowing operation until a potential failure is detected On-condition task objective is to maximize the useful life of each piece of equipment by allowing operation until a potential failure is detected Task includes only inspection portion of the maintenance action Task includes only inspection portion of the maintenance action Can be accomplished with Condition Monitoring/PdM/PHM systems Can be accomplished with Condition Monitoring/PdM/PHM systems Task Development ON CONDITION TASK

Questions: What is the Functional Failure? What is the Functional Failure? What is the Potential Failure? What is the Potential Failure? What is the Potential Failure to Functional Failure (PF) interval and how consistent is it? What is the Potential Failure to Functional Failure (PF) interval and how consistent is it? Can a task be developed that provides an acceptable probability of detecting the potential failure prior to functional failure? Can a task be developed that provides an acceptable probability of detecting the potential failure prior to functional failure? Is the task and required interval practical? Is the task and required interval practical? Task Development ON CONDITION TASK

Functional Failure: Inability of item to perform a specific function within specified performance limits Inability of item to perform a specific function within specified performance limits Functional Failure is identified and documented during FMECA Functional Failure is identified and documented during FMECA FF condition may be redefined for purposes of OC task FF condition may be redefined for purposes of OC task If function ceases, Functional Failure has occurred If function ceases, Functional Failure has occurred May also be defined as prior to complete loss of function May also be defined as prior to complete loss of function Must be known before valid Potential Failure-to- Functional Failure interval can be established Must be known before valid Potential Failure-to- Functional Failure interval can be established Task Development ON CONDITION TASK

OPERATING AGE A FUNCTIONALFAILURE POTENTIALFAILURE B C DEFINED POTENTIAL FAILURE CONDITION DEFINED POTENTIAL FAILURE CONDITION Inspection Interval Functional Failure: PRACTICAL? TASK INTERVAL PRACTICAL? III Task Development PF Interval ON CONDITION TASK DEFINED FUNCTIONAL FAILURE CONDITION Functional Capability

Potential Failure: Definable and detectable condition that indicates a functional failure will occur Definable and detectable condition that indicates a functional failure will occur Potential failure is a definable and detectable degradation characteristic Potential failure is a definable and detectable degradation characteristic Defining Potential Failure: Defining Potential Failure: at earliest detectable condition will lengthen the On Condition task interval at earliest detectable condition will lengthen the On Condition task interval closer to functional failure will allow greater usage of available life of item closer to functional failure will allow greater usage of available life of item Task Development ON CONDITION TASK

OPERATING AGE A FUNCTIONALFAILURE POTENTIALFAILURE B C DEFINED POTENTIAL FAILURE CONDITION DEFINED POTENTIAL FAILURE CONDITION Inspection Interval FUNCTIONAL CAPABILITY Potential Failure: TASK INTERVALPRACTICAL TASK INTERVAL PRACTICAL? III Task Development PF Interval ON CONDITION TASK DEFINED FUNCTIONAL FAILURE CONDITION

PF Interval: PF Interval: The time in some traceable operating unit between occurrence of potential and functional failure Safety consequences: PF interval may need to be determined analyticallyor through laboratory testing PF interval may need to be determined analyticallyor through laboratory testing Method used depends on the failure mode Method used depends on the failure mode Age Exploration may be necessary to collect data Age Exploration may be necessary to collect data Task Development ON CONDITION TASK

PF Interval: Task Development Non-Safety consequences: Gather data from experience/CMMS data Gather data from experience/CMMS data Age Exploration on in-service equipment Age Exploration on in-service equipment Method used depends on the failure mode Method used depends on the failure mode ON CONDITION TASK

OPERATING AGE A FUNCTIONALFAILURE POTENTIALFAILURE B C DEFINED POTENTIAL FAILURE CONDITION DEFINED POTENTIAL FAILURE CONDITION Inspection Interval PF Interval: TASK INTERVALPRACTICAL TASK INTERVAL PRACTICAL? III Task Development ON CONDITION TASK DEFINED FUNCTIONAL FAILURE CONDITION PF Interval FUNCTIONAL CAPABILITY

Task interval determined from PF interval Task interval determined from PF interval Usually, inspection must occur at least once during PF interval Usually, inspection must occur at least once during PF interval More inspections during the PF interval may be required to ensure acceptable levels of safety, mission, and economics are achieved More inspections during the PF interval may be required to ensure acceptable levels of safety, mission, and economics are achieved Task Development Determining Task Interval: ON CONDITION TASK

OPERATING AGE A FUNCTIONALFAILURE POTENTIALFAILURE B C DEFINED POTENTIAL FAILURE CONDITION DEFINED POTENTIAL FAILURE CONDITION Task Interval : TASK INTERVAL III Task Development ON CONDITION TASK DEFINED FUNCTIONAL FAILURE CONDITION PF Interval FUNCTIONAL CAPABILITY

Task Development Determining Task Interval: ON CONDITION TASK Inspection Interval (I): (Ref: NAVAIR ) I = PF/n I = PF/nwhere: PF = interval from potential failure to functional failure n = number of inspections during PF interval

Example: Determining On Condition Inspection Interval for Tail Hook CRACK LIMITS 1/64 3/64 0 FUNCTIONAL FAILURE POTENTIAL FAILURE ARRESTMENTS Task Development ON CONDITION TASK

Example: ARRESTMENTS 10 Sample A B Determining On Condition Inspection Interval for Tail Hook Inspection Interval = 10 Arrests Task Development ON CONDITION TASK 10

Determining Task Interval: Task Development Failure modes with Safety Consequences: Goal is to develop task interval that will reduce the probability of experiencing a failure to an acceptable level Goal is to develop task interval that will reduce the probability of experiencing a failure to an acceptable level Failure Modes with Non Safety Consequences: Goal is to determine task interval that yields the most cost effective task realizing some functional failures may be OK if overall cost is minimized. Goal is to determine task interval that yields the most cost effective task realizing some functional failures may be OK if overall cost is minimized. ON CONDITION TASK

Engineering judgment using maintenance data, engineering/technical information, SME input, etc. Engineering judgment using maintenance data, engineering/technical information, SME input, etc. If PF is unknown but failure mode clearly has a progressive failure mechanism, work backwards from an existing effective task to determine a PF interval If PF is unknown but failure mode clearly has a progressive failure mechanism, work backwards from an existing effective task to determine a PF interval If current task is less effective than desired, adjust PF as a function of current task effectiveness to get new PF If current task is less effective than desired, adjust PF as a function of current task effectiveness to get new PF Analytical methods provided in NA Analytical methods provided in NA Task Development Estimating Methods: ON CONDITION TASK

Determining Task Interval: Task Development ON CONDITION TASK Determining whether any particular analytical method is appropriate is the responsibility of the analyst Common Errors: Getting bogged down by lack of data (use best judgment) Getting bogged down by lack of data (use best judgment) Using existing task interval instead of analyst judgment when NOT appropriate Using existing task interval instead of analyst judgment when NOT appropriate Lack of documentation of decisions in memo field Lack of documentation of decisions in memo field Excessive conservatism Excessive conservatism Using MTBF Using MTBF

Determining Task Interval: Task Development ON CONDITION TASK Additional Considerations: Ensure repair actions do not reduce the PF interval, otherwise a new PF interval may be required for repaired items Ensure repair actions do not reduce the PF interval, otherwise a new PF interval may be required for repaired items Explore various inspection techniques Explore various inspection techniques Ensure PF is adjusted for the inspection technique Ensure PF is adjusted for the inspection technique Ensure published repair limits are consistent with Potential Failures identified by OC tasks Ensure published repair limits are consistent with Potential Failures identified by OC tasks

Review and Summary Introduction Learning Objective – Learning Objective Task Development Questions to be addressed – Questions to be addressed – Identifying Failure Resistance Indicator – Identifying Functional Failure Condition – Identifying Potential Failure Condition – Determining PF Interval – Determining Task Interval – Default Methods ON CONDITION TASK Module Objective – Provide detailed information for evaluating and developing an On Condition task. developing an On Condition task.

End of Module up next…….. Hard Time Task End of Module up next…….. Hard Time Task