Continuing analysis and surveillance system (CASS)

Reliability & Safety

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AIRCRAFT MAINTENANCE

Reliability

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Definition“The probability that an item will perform a

required function, under specified conditions without failure, for a specified amount of time.”

2 Main ApproachesLooks at Whole Operation : Dispatch

ReliabilityLooks at Maintenance Program : Reliability

Program

Reliability

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Term ReliabilityOverall ReliabilityComponent ReliabilityProcess ReliabilityMaintenance Program Reliability

Types of Reliability (4 types)Statistical ReliabilityHistorical ReliabilityEvent-oriented ReliabilityDispatch Reliability

Reliability

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Event-oriented ReliabilityConcerned with one-time events such as

bird strikes, hard landing, in-flight shutdowns, or others accidents or incidents, which these are events that do not occur on a regular basis.

Each occurrence must be investigated to determine the cause and to prevent or reduce the possibility of recurrence of the problem.

Reliability

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Dispatch Reliability (DR)DR is a measure of the overall

effectiveness of the airline operation with respect on-time departure. It is a simple calculation based on 100 flights.DR involves more than just maintenanceDispatch delays should look at the whole

operation.On-time departure means that the aircraft

has been “pushed back” from the gate within 15 minutes of the scheduled departure time

Reliability

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Dispatch reliability

Reliability

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Reliability DepartmentResponsibility of monitoring failure rates,

removals of A/C systems and components to measure the effectiveness of the overall maintenance program

Data Collection Preliminary Investigation Issue Alert Notices Monitor Results

Reliability

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Reliability ProgramA set of rules and practices for managing

and controlling a maintenance programMonitor the performance of the vehicles and

their associated equipment and call attention to any need for corrective action

Monitor the effectiveness of corrective actions

Provide data to justify adjusting the maintenance intervals

Reliability

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Elements of a Reliability ProgramData collectionProblem area alertingData DisplayData analysisCorrective actionsFollow-up analysisMonthly report

Reliability

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Data collectionFlight time and cycleCancellations and delay over 15 minutesUnscheduled component removalsUnscheduled engine removalsIn-flight shutdowns of engines (IFSD)Pilot reports or logbooksCabin logbookComponent failure (shop)Maintenance check package findingsCritical failures

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Problem area alertingAn alerting system

Identify those areas where the performance is significantly different from the normal

Alert level is based on a statistical analysisAlert level is set at one to three standard

deviations above the mean rateAlert level is referred as UCL (Upper Control

Limit)Additional calculation that can be made to

smooth the curve (3 months average) and help eliminate “false alerts”

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Problem area alerting (cond.)Setting and adjusting alert levelsRecommended that alert levels be

recalculated yearly

UCL (Upper Control Level)

3 months Offset

Control Chart

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Data analysisReliability Department

a preliminary analysis to determine if the alert is valid

If valid, on-alert condition is sent to engineering for a more detailed analysis

Engineering DepartmentTroubleshoot the problemIssue EO (Engineering Order)Recommendations to the Airline Maintenance

Program Review Board (MPRB)

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Corrective actionsModifications of equipmentCorrection to line, hangar or shop processes

or practicesDisposal or defective partsTraining of mechanicsAddition of maintenance tasks to the programDecreased in maintenance intervals

Completion of the corrective action is noted in the monthly reliability report

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

Reliability

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Follow-up analysisVerify the corrective action taken was indeed

effectiveReflected in decreased event ratesIf no significant change, corrective action

should be reanalyzed

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Monthly reportWorking tool for maintenance managementPicture of what problems are encountered

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

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Reliability Program DocumentEvery aspect of the reliability must be

documented in an official document signed be MPRB chairman and approved be the regulatory authority

Include:Detailed discussionMethods used to determine alert levelsRules relative to changingDefine MPRB activities and ResponsibilityMonthly Report Format

Submitted to FAA for approval

▪ Data collection ▪ Problem area alerting ▪ Data Display ▪ Data analysis ▪ Corrective actions ▪ Follow-up analysis ▪ Monthly report

Safety

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Traditional Safety ManagementLoss Control - Correction approachLoss control is the tools for - Prevention

- Reduction - Elimination

Cause of incident and accident is -Unsafe Action -Unsafe Condition

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Loss Causation Model

1. Loss - Loss of Direct cost

- Loss of Indirect cost2. Incident3. Immediate Cause

- Low standard action and Low standard condition

4. Basic Cause - Personal Factor and Job Factor5. Lack of Control

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Loss Control Management Process1. Identification of Work2. Set Standard3. Measurement4. Evaluation5. Commendation and Correction

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Modern Loss Management

1. Source of Loss- People- Equipment- Material- Enviroment

2. Loss Control systems - International Safety Rating System (ISRS)

-US- Total Loss Control Management-UK

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Modern Safety Management

Modern Safety Management – Prevention, Risk Assessment and Risk control approaches

Modern Safety Management is Loss Control Management

Modern Safety Management used POLC framework

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Modern Safety Management

There are 4 approach to Modern Safety Management

1. Management concept2. Management information system3. Performance standard4. Measurement and Evaluation system

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System Safety

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FAA - Safety Risk Matrix FAA Advisory Circular No. 120-92, Introduction of Safety Management Systems for Air Operators

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FAA - Safety Risk Matrix

Unacceptable (Red). Where combinations of severity and likelihood cause risk to fall into the red area, the risk would be assessed as unacceptable and further work would be required to design an intervention to eliminate that associated hazard or to control the factors that lead to higher risk likelihood or severity.

Acceptable (Green). Where the assessed risk falls into the green area, it may be accepted without further action. The objective in risk management should always be to reduce risk to as low as practicable regardless of whether or not the assessment shows that it can be accepted as is. This is a fundamental principle of continuous improvement.

Acceptable with Mitigation (Yellow). Where the risk assessment falls into the yellow area, the risk may be accepted under defined conditions of mitigation. An example of this situation would be an assessment of the impact of a non-operational aircraft component for inclusion on a (MEL). Defining an Operational (“O”) or Maintenance (“M”) procedure in the MEL would constitute a mitigating action that could make an otherwise unacceptable risk acceptable, as long as the defined procedure was implemented. These situations may also require continued special emphasis in the safety assurance function

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General Safety Rules

Fire prevention & protectionHangar deluge systemsFall prevention and ProtectionStorage and handlingSmoking regulationHangar safetyShop safetyLine safety

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Hand Signal

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Safety Management System

ICAO has established a framework for an SMS that incorporates four basic components and 12 elements as shown here:

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MEDA Corrective Actions

THE END