Chapter 18
Reliability
Reliability
• Reliability equals consistency
• Probability an item performs a required
function
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Under specific conditions
Specified amount of time
According to intended design
• Detect and resolve problems
Reliability
• Two approaches
• Whole airline operation
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Dispatch reliability
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Delays
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Achieve on-time departures
Maintenance
Flight operations
ATC
Overlook maintenance that do not cause delays
Do not track/investigate
• Maintenance operation (M&E)
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According to intended design
Reliability
• Two approaches
• Maintenance operation
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Address problems of maintenance
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Whether or not delays or caused
Provide analysis/corrective actions
Reliability
• Types
• Statistical reliability
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Collection/analysis of data (events)
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Failure, removal, repair rates
Events per 1000 flight hours/per 100 flight cycles
Not always appropriate
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Not enough data points
Valid approach (p. 219)
Reliability
• Types
• Historical reliability
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Comparison of current event rates to past event
rates
Not always appropriate
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New equipment introduced
Can be used to establish statistical program
Reliability
• Types
• Event-oriented reliability
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One-time events (not on daily basis)
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Bird strikes
In-flight engine shutdowns
Lightning strikes
Accidents/incidents
ETOPS (probably in statistical/historical also)
Reliability
• Types
• Dispatch reliability
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Measure of overall effectiveness
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In relation to on-time departures
Based on 100 flights (percentage)
Should look at whole operation
Airlines may not track problems not causing
delays
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Airline procedures may need adjusting
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Reliability
• Rules/practices to manage/control
maintenance program
• Monitor performance
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Vehicles
Equipment
Call attention for needed corrective action
Monitor effectiveness of corrective actions
Justify adjusting maintenance program
Reliability
• Elements of program
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Data collection
Problem area alerting
Data display
Data analysis
Corrective actions
Follow-up analysis
Monthly report
Data Collection
• Elements of program
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Flight time/cycles per aircraft
Cancellations/delays over 15 minutes
Unscheduled component removals
Unscheduled engine removals
In-flight engine shutdowns
Pilot reports/logbook write-ups
Cabin logbook write-ups
Component failures
Maintenance check package findings
Critical failures
Problem Detection
• Alerting system
• Performance significantly different from
normal
• Need to understand equipment
• Know failure patterns
• Setting alert levels
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Set to useable level
Indicate problem exists or may be developing
Know when to proceed or refrain from
investigating
• Alert levels recalculated yearly
Data Display
• Tabular or graph data
• Tabular
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Compare event rates with other data
• Graph
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View month to month performance
Show increasing/decreasing rates
Data Analysis
• Preliminary Analysis
• Item goes on alert status
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Determine if alert is valid
Sent to engineering for detailed analysis
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Troubleshoot
Determine required action
Issue EO
Corrective Action
• Results
• Modification of equipment
• Change/correct line, hangar, shop
processes/practices
• Disposal of defective parts
• Training of mechanics
• Addition of maintenance tasks to program
• Decrease in maintenance intervals
• Corrective action to be completed within 1
month of EO issue
Follow-up Analysis
• Action
• Verify corrective action effective
• No improvement – back on alert status
• Data analysis repeated
Data Reporting
• Monthly report
• What problems are encountered
• What is being done
• Concentrate on items
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Just gone on alert
Under investigation
Completed corrective actions
Progress on other items
Additional Functions
• Provide changes to program
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Specific tasks
Adjustments in intervals to tasks
Processes
Works with MPRB
MPRB
• Meets monthly - discuss
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Overall status of maintenance reliability
Items on alert
Establishment of alert levels
Adjustment of the alert levels
Works with MPRB