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.

1. CHECK INTERVAL ESCALATION Prepared by Eng. Mohammed Salem Awodh Adviser Yemenia THE 9 TH ANNUAL MIDDLE EAST AIRLINE ENGINEERING & MAINTENANCE CONFERENCE

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

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

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

30. 29 HYDRAULIC SYSTEM II – Pilot Reports Weibull Analysis Group Data

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

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