Check interval escalation
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The document discusses methods for extending maintenance check intervals for aircraft to increase availability and reduce costs. It proposes using reliability data from aircraft systems to determine if check intervals can be safely increased through analytical approaches like Weibull analysis. A case study models extending a check C interval from 1600 to 2000 flight hours for a hydraulic system. Statistical tests of reliability parameters from the system's data over several years would need to support the interval extension without adversely affecting safety.
Check interval escalation
- 1. CHECK INTERVAL ESCALATION Prepared by Eng. Mohammed Salem Awodh Adviser Yemenia THE 9 TH ANNUAL MIDDLE EAST AIRLINE ENGINEERING & MAINTENANCE CONFERENCE
- 2. OVERVIEW INTRODUCTION MRB Document Forms Basis Of Initial Maintenance First Item For Development: Extending Interval For Major Maintenance Visits. Escalation Period No Problems For Large Carries Hard For Small Carries Methodology Can be Applied For check A, B & C. Simulated Case Study For A Small Operator.
- 3. WORLD WIDE FLEET SITUATION III I II AIRLINES CHECK CARRIED AT …… Flt Hr ( A / B /C ) Recommended Value By Manufacture Weight Average value by Fleet World
- 4. WORLD WIDE FLEET SITUATION Region I : Usually Large Carries Region II : Airlines Who Are Adapted & Copied The Manufacture Recommendations Region III : Small Carries
- 5. CHECK A INTERVALS FOR 737-200 WORLDS FLEET
- 6. CHECK B INTERVALS FOR B737-200 WORLDS FLEET
- 7. CHECK C INTERVALS FOR B737-200 WORLDS FLEET
- 8. CHECK ESCALATION OBJECTIVE Aircraft Maintenance And Mechanical Reliability are not effected significantly when Scheduled Maintenance Increases. Systems Rates Flt Hours / Cycles
- 9. CHECK ESCALATION CHECK INTERVAL ESCALATION FACTORS : Additional Availability of Airplanes. Increased Workload per check vs any decrease in the man hours per flight hours Utilization of Maintenance facilities and personal. Size of work crew required Age of Airplanes. Experience level of personal. Operational Environment of Airplanes.
- 10. CHECK ESCALATION ATA SPECIFICATION 100 SYSTEMS AIRCRAFT SYSTEMS Structures Group 51 Structures General ……… ……… ……… ……… 57 Wings Mechanical / Electrical Systems Group Air Conditioning ……… ……… ……… ……… 49 Auxiliary Power Unit ( APU ) Power plant Group 71 Power plant General ……… ……… ……… ……… 82 Engine Water Injection
- 11. CHECK ESCALATION METHODLOGIES Sampling Approach. Analytical Approach.
- 12. METHODLOGIES SAMPLING APPROACH (Prerequisite) Pro-Active Regulatory Liaison Group. Sufficient Sample Aircraft. Expert Engineering/ Maintenance/ Planning Team Effective Reliability Program.
- 13. METHODLOGIES ANALYTICAL APPROACH (Prerequisite) Sufficient Data. Technical & Statistical Skill. Effective Reliability Program. Advance Computer Programmer
- 14. ANALYTICAL APPROACH RELIABILITY PARAMETERS Mechanical Delays. Pilot Reports. Non-Routine Work at Scheduled Maintenance Checks.
- 15. ANALYTICAL APPROACH RELIABILITY LEVEL TIME
- 16. ANALYTICAL APPROACH Support extension Support extension Support extension Undetermined extension Time Since “C” Check – Flight Hours Reliability Parameter INTERVAL EXTENSION PROPOSED INTERVAL CURRENT INTERVAL
- 17. ANALYTICAL APPROACH The Flow Chart is illustrated the Analytical Approach Effective Parameters for Measuring the Safety Factors Reject the Result Evaluating the Rate Function At the Target Period for the Specified System Define Level Of Confidence Data By ATA Chapters Is % change of the rate of the extended period to the actual period is < 0.05 Accept the Result YES NO
- 18. ANALYTICAL APPROACH THE FOLLOWING FACTORS ARE NOT ADVERSELY AFFECTED BY INTERVAL EXTENSION : MECHANICAL DELAYS PILOT REPORTS TOTAL NON-ROUTINE MAINTENANCE NON-ROUTINE MAINTENANCE GENERATED BY SPECIFIC “ C “ CHECK TASKS
- 19. ANALYTICAL APPROACH EACH ANALYSIS IS SUBJECTED TO : MORE THAN ONE STATISTICAL TEST ASSIGN 95 % CONFEDNCE LEVEL DATA SELECTED OVER 5 YEARS PERIOD THE BASE SCALES OF THE ANALYSIS ARE FLIGHT HOURS AND CYCLES BY ATA CHAPTER NUMBER
- 20. MECHANICAL DELAYS THIS SYSTEM FACTOR SHOULD ANALYSIS BY : WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARED TEST ( X 2 )
- 21. PILOT REPORTS THIS SYSTEM FACTOR SHOULD ANALYSIS BY : WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARED TEST ( X 2 )
- 22. NON-ROUTINE MAINTENANCE LEVELS THIS SYSTEM FACTOR SHOULD ANALYSIS BY : WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARED TEST ( X 2 )
- 23. NON-ROUTINE MAINTENANCE GENERATED FROM “C” CHECK MAINTENANCE TASKS ALL THE TASKS COVERED BY CHECKS “A” AND “ B” ARE ELIMINATE IN THE “C” CHECK PACKAGE. MAXIMUM ALLOWABLE ITEMS PER REMINING TASKS WITH 95 % CONFIDENCE BINOMIAL DISTRIBUTION POISSON DISTRIBUTION
- 24. OUTCOMES MECHANICAL DELAY RATE WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARE TEST PILOT REPORT RATE WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARE TEST TOTAL NON-ROUTINE MAINTENANCE WEIBULL ANALYSIS LEAST SQUARES REGRESSION CHI SQUARE TEST ALL SHOULD SUPPORT INTERVAL EXTENSION
- 25. CASE STUDY Simulated Case Study is developed Objective : Escalation Check C Current Interval : 1600 Flt Hrs Target Interval : 2000 Flt Hrs Escalation Interval : 400 Flt Hrs
- 26. DATA COLLECTIONS Case Study Ungroup Data Kolomograph Test Group Data CHI Square Test
- 27. 29 HYDRAULIC SYSTEM I – Mechanical Delays Weibull Analysis Ungroup Data
- 28. 29 HYDRAULIC SYSTEM I – Mech. Delays (Distribution ) KOLMOGOROV TEST
- 29. HYDRAULIC SYSTEM I – Mechanical Delays (Rate)
- 30. 29 HYDRAULIC SYSTEM II – Pilot Reports Weibull Analysis Group Data
- 31. HYDRAULIC SYSTEM II – Pilot Reports (Rate) Evaluation Weibull Parameters
- 32. 29 HYDRAULIC SYSTEM II – Pilot Reports (Rate)
- 33. 29 HYDRAULIC SYSTEM III – Total Non- Routine Items Weibull Analysis Group Data
- 34. 29 HYDRAULIC SYSTEM III – Total Non- Routine Items Evaluation Weibull Parameters
- 35. 29 HYDRAULIC SYSTEM III – Total Non- Routine Items Rate
- 36. HYDRAULIC SYSTEM VI – Non- Routine Maintenance - Generated By Specific “ C “ Check Tasks
- 37. GO, NO GO DECISION The Previous Steps should be repeated for all ATA Systems Go Decision if all systems analysis are support positive results. Systems, those are not satisfied the conditions, should review carefully, by issuing service difficulty reports.
- 38. SUMMARY Small Carriers can implement these techniques. Weibull Analysis is a powerful approach which can be used for Non-Group Data and Group Data. To avoid type II error The Previous Steps are subjected to Kolomogrovo Test.
- 39. Contact Further Information: Mohammed Salem Awad Tel: 00967 734777518 Email: smartdecision2002@yahoo.com www.freewebs.com/wingsofwisdom/ www.freewebs.com/art-of-knowledge/ www.standout-from-the-crowds.webs.com