Investigating FOD Damage Part 3 – Denver FOD Conference

1. Investigating FOD DamagePart 3 – Denver FOD Conference George A. Morse, FAST, Inc.

2. Example 1: DC-10 #2 • Vibrations in #2 engine during take-off • Take-off aborted • Engine pulled for fan blade damage George A. Morse, FAST, Inc.

3. Example 1: DC-10 #2 Good place to sample Circular symmetry Apparent thread marks George A. Morse, FAST, Inc.

4. Example 1: DC-10 #2 LE fan blade damage George A. Morse, FAST, Inc.

5. Example 1: DC-10 #2: Analysis • Power setting was high (takeoff) • Impacts resulted in blade tearing and loss of blade material • Most impacts occurred to the LE concave surface (Indicates the impacting object entered through the intake) George A. Morse, FAST, Inc.

6. Example 1: DC-10 #2: Analysis • There is circular damage symmetry • There is rectangular damage symmetry • There are apparent thread marks • Blades are made of titanium George A. Morse, FAST, Inc.

7. Example 1: Analysis FAST samples reveal nickel - chrome plated steel tool material George A. Morse, FAST, Inc.

8. Example 1: DC-10 #2: Conclusion Source of thread marks A nickel - chrome plated crescent wrench accounts for the damage George A. Morse, FAST, Inc.

9. Example 2: Blade fracture in HPC • Engine removed for compressor blade damage. • One HPC-1 blade suffered loss of material • Numerous other blades suffered impact damage • Borescope inspection revealed no damage to fan or fan booster. • Compressor had been completely restored during 375 hours prior to this event. George A. Morse, FAST, Inc.

10. Example 2: Blade fracture in HPC • Many blades revealed TE section scratches/dents on concave surface • Typical when an object becomes stuck on a vane aft of blade • As blade rotates, it makes contact with the object • FAST samples revealed that stuck object was liberated blade material George A. Morse, FAST, Inc.

11. Example 2: Blade fracture in HPC • Several IGV’s show TE impacts • FAST samples confirmed impacts due to missing section from broken HPC-1 blade George A. Morse, FAST, Inc.

12. Example 2: Blade fracture in HPC • HPC-2 blade shows a LE impact to the concave surface • Not expected shape from liberated airfoil section of broken HPC-1 blade George A. Morse, FAST, Inc.

13. Example 2: Blade fracture in HPC Macro photo of blade shows: • LE impact to concave surface • Fatigue zone • Fast fracture zone Fatigue zone LE concave surface impact Fast fracture George A. Morse, FAST, Inc.

14. Example 2: Blade fracture in HPC 20X SEM photo showing LE impact deformation to concave surface George A. Morse, FAST, Inc.

15. Example 2: Blade fracture in HPC 1000X SEM photo showing fatigue striations in fatigue crack growth zone aft of impact George A. Morse, FAST, Inc.

16. Example 2: Blade fracture in HPC 500X SEM photo showing ductile dimples at tip fast fracture zone George A. Morse, FAST, Inc.

17. Example 2: Blade fracture in HPC 300 stainless steel found in fractured blade LE impact. George A. Morse, FAST, Inc.

18. Example 2: Blade fracture in HPC 300 stainless steel was also found in HPC-2 LE impact. George A. Morse, FAST, Inc.

19. Example 2: CONCLUSIONS • Engine suffered impact from aircraft 300 series stainless steel fastener hardware • Impact occurred many engine cycles prior to blade breakage • Impact created a stress concentration from which a fatigue crack began to grow • Blade broke when remaining blade material holding blade together could no longer sustain normal engine load George A. Morse, FAST, Inc.

20. Example 3: Blade Failure on Takeoff George A. Morse, FAST, Inc.

21. Example 3: Blade Failure On Takeoff • Flight crew heard loud bang and noticed vibration on #2 engine during takeoff roll • Takeoff was aborted • While taxing off the runway and back to gate, another aircraft reported seeing smoke and flames coming from the #2 engine (aft fuselage mounted) • Engine was shut down George A. Morse, FAST, Inc.

22. Example 3: Investigation There was no LE impact damage to the inlet struts One inlet strut showed TE damage George A. Morse, FAST, Inc.

23. Example 3: Investigation A number of blades show circular shaped impacts, which are not the shape of the blade edges George A. Morse, FAST, Inc.

24. Example 3: Investigation Blade fracture convex surface Blade fracture concave surface George A. Morse, FAST, Inc.

25. Example 3: Investigation Macro fracture features indicate instantaneous overload 500X SEM photo confirms George A. Morse, FAST, Inc.

26. Example 3: Investigation Fractured blade shows a LE concave surface impact deformation FAST sample from LE reveals aluminum as foreign debris George A. Morse, FAST, Inc.

27. Example 3: Conclusions • Engine ingested an aluminum object, the size and shape suggests a flash light • Power setting was high (takeoff) • Blades broke instantaneously • Taxiing with engine running resulted in more damage George A. Morse, FAST, Inc.

28. Example 4: HPC-10 Blade Failure George A. Morse, FAST, Inc.

29. Example 4: HPC-10 Blade Failure LE impact to concave surface of HPC-1 blade HPC-1 through HPC-9 damage included small cylindrical and circular dents and nicks Damage aft of HPC-10 was heavy George A. Morse, FAST, Inc.

30. Example 4: Investigation TE fast fracture Fatigue LEimpact Beach marks HPC-10 blade fracture with appropriate areas labeled George A. Morse, FAST, Inc.

31. Example 4: Investigation 300 series stainless steel found as foreign debris on HPC-10 LE impact George A. Morse, FAST, Inc.

32. Example 4: Investigation 300 series stainless steel found as foreign debris on HPC-1 & HPC-2 impacts George A. Morse, FAST, Inc.

33. Example 4: Investigation 300 series stainless steel safety wire accounts for the physical damage George A. Morse, FAST, Inc.

34. Example 4: Conclusion • Engine suffered impact by aircraft safety wire • LE impact to HPC-10 blade created a stress concentration from which a fatigue crack began to grow • Blade broke when crack grew to approximately 70% across the chord width • Impact by safety wire occurred many engine cycles prior to blade breakage George A. Morse, FAST, Inc.