1. Keith Legg 847-680-9420 Test Status Overview HCAT Program Review NASA, Florida Dec 13,14, 2000

2. Keith Legg 847-680-9420 Rationale A lot of data has been generated in HCAT/CHCAT program in the past 3 or 4 months Aim is to show overall status - where we are in testing and what we have learned overall  Put current data in a logical order  Address what we are doing to resolve some testing issues  Suggest some “compartments” for existing and new data

3. Keith Legg 847-680-9420 Overview Aircraft use of HVOF coatings Why are we doing this? - commercial flight tests Overall status of JTP tests  JTP - Corrosion, wear, fatigue, embrittlement, impact  Ancillary - Process specs, producibility, additional corrosion, additional fatigue, failure mechanisms Conditions seen by real parts Summary of findings to date What does all this mean for actual usage?  Where does it work just fine?  Where do we need to worry?

4. Keith Legg 847-680-9420 Flight testing - Why are we doing this? Flight testing (Boeing, Delta, Lufthansa etc.) shows acceptable performance with no serious problems  Wear performance much better than chrome  no gouges, striations, flaking, etc. commonly seen in Cr  better seal life if Ra~4  ” (rapid seal damage if rough)  some FPI crack pattern indications on Lufthansa aft inner cylinders (Barkhausen showed no crack penetration to substrate), nothing requiring removal from service Typical chrome damage - axle

5. Keith Legg 847-680-9420 Production use of HVOF WC-Co and WC-CoCr coatings

6. Keith Legg 847-680-9420 Production use of HVOF WC-Co and WC-CoCr coatings (cont.) Qualified for landing gear repair <0.010”

7. Keith Legg 847-680-9420 Production use of HVOF landing gear coatings - Messier-Dowty Note production use on high performance aircraft

8. Keith Legg 847-680-9420 Data summary: Landing Gear JTP - Coupon test data

9. Keith Legg 847-680-9420 Data summary: Propeller Hub JTP - Coupon test data

10. Keith Legg 847-680-9420 Corrosion C-HCAT B117  JTP work complete  HVOF performed significantly better than chrome - Pass US-HCAT B117  Initial test results reported in Ottawa, Aug 00  HVOF coatings worse than Cr - Fail  Appears to be a testing issue Outstanding issues - resolution of US-HCAT results  Retesting under way  Different sealing - Boeing Cd method  2 different geometries (Flats and cylinders)  2 different deposition conditions (Southwest Aero, Hitemco)  2 different cabinets

11. Keith Legg 847-680-9420 Embrittlement Tests partially complete  Sequence 1 - HVOF does not cause embrittlement - Pass  Sequence 2 - Not yet complete  H 2 can diffuse through HVOF coating  May need longer bake  Sequence 3 begun - no data yet Outstanding issues  Environmental embrittlement measurements in process  Coating may lower Kt - calculations and tests under way at Heroux

12. Keith Legg 847-680-9420 Fatigue - WC-Co WC-Co  US-HCAT testing complete  All WC-Co air fatigue data equal to or better than Cr - Pass  All WC-Co corrosion-fatigue data equal to or better than Cr - Pass  Delamination from some specimens at high cycles WC-CoCr  WC-CoCr 0.003” delamination at high load - Pass below 180 ksi, Fail above 180 ksi  WC-CoCr 0.010” delamination at high load - Pass below 125 ksi, Fail above 125 ksi  WC-CoCr corrosion-fatigue - Fail?? Not a structural issue, but a functional issue (Messier-Dowty) Outstanding issues  Results of WC-CoCr fatigue testing  being addressed under Ancillary Testing

13. Keith Legg 847-680-9420 Wear Fretting and sliding (hydraulic)  Data evaluation largely complete  HVOF better than or equal to Cr Rig and flight tests all show better wear performance  Less striation, wear, roughening (Delta, Greene Tweed)  Less wear and leakage of seals (Greene, Tweed)

14. Keith Legg 847-680-9420 Impact Drop ball testing  Under way Gravelometry (Boeing)  Completed - HVOF as good as or better than Cr - Pass

15. Keith Legg 847-680-9420 Data summary: Landing Gear JTP - Rig and flight testing

16. Keith Legg 847-680-9420 Data summary: Propeller Hub JTP Rig and flight testing

17. Keith Legg 847-680-9420 Hydraulic testing - Greene, Tweed PTFE (Enercap) much better performance with WC  low leakage  low rod wear Elastomer rapidly damaged  not a problem with long stroke utility actuators and landing gear at 4 Ra 4-9  ” Ra

18. Keith Legg 847-680-9420 Landing gear rig tests Boeing F/A-18 E/F landing gear pins  HVOF coatings “passed” full scale rig fatigue test  darkened, but no wear damage, passed MPI Outstanding - Additional full scale tests to be done by C-HCAT ä Messier-Dowty F-18 E/F NLG fatigue ä Messier-Dowty F-18 E/F drag brace fatigue o including catapult loads ä BFG Dash-8/400 MLG ä BFG NLG steering actuator ä BFG simulated piston fatigue

19. Keith Legg 847-680-9420 Flight tests n Delta B737, 757, 767 nose and main landing gear ä Inner cylinders, axles, axle sleeves o Passed - WC-CoCr qualified for O&R n Boeing 767-400 ä HVOF WC-CoCr flight qualified and used in production n Canadian F-18 MLG ä Messier-Dowty polygon repair o WC-CoCr o Repair scheme approved n Outstanding - NADEP-JAX P3, DND C-130 testing

20. Keith Legg 847-680-9420 Data summary - Ancillary tests

21. Keith Legg 847-680-9420 Process parameters WC-Co optimized by Jerry Schell by DOE methods  OO-ALC, Hitemco - JP 5000, DJ  Process designed for 8-12 Almen compressive stress WC-CoCr optimized by Jean-Gabriel Legoux, NRC by DOE methods  DJ-gun at NRC and VacAero  Process designed for 8-12 Almen compressive stress  Coating parameters different from QPL conditions used by Southwest Aero

22. Keith Legg 847-680-9420 Grinding and finishing Overall finding - for seals need 4  ” or less Ra  Use fine grind or superfinish (specify other parameters?) Low stress grinding developed by Jon Devereaux at NADEP-JAX  used on all US-HCAT samples Surface measurement and superfinishing developed for landing gear by Jay Randolph at Delta Testing carried out by John Falkowski (Boeing) and Jim Nuse (Southwest Aeroservice) - AESF paper Additional testing under way  Boeing, SW Aero, Sulzer Metco, Engelhard, Praxair, Green Tweed, Supfina, Delta

23. Keith Legg 847-680-9420 Stripping Water jet does not work very well Rochelle salt works well for WC-Co and WC-CoCr  SW Aero, Sulzer Metco  NADEP-Cherry Point, NTS Testing at Praxair and others shows no embrittlement with strippers No good method for T400 yet Outstanding - need good chemical strip for Tribaloy

24. Keith Legg 847-680-9420 Fluid compatibility Under way shortly at Heroux Will include evaluations of hydrogen embrittlement due to fluids

25. Keith Legg 847-680-9420 NDI FPI best method so far  Delta, Boeing MPI not effective Boeing has used Barkhausen with some success Heroux testing begun Outstanding - how detect cracks in substrate without removing coating?

26. Keith Legg 847-680-9420 Corrosion All HCAT generic, C-HCAT, Lufthansa data on flats shows HVOF having better performance than Cr  US-HCAT Landing gear JTP data on rods showed worse than Cr - Fail  Repeating with better edge seal - comparing sample shapes, deposition conditions, test locations Outstanding - Resolution of poor US-HCAT test performance (under way)

27. Keith Legg 847-680-9420 Fatigue and fracture Fatigue of WC-CoCr - the picture folks took back from Ottawa meeting

28. Keith Legg 847-680-9420 Fatigue and fracture Findings of cracking by AFRL (Bob Ware) Careful analysis done at NRC (Jason Dyer, Peter Au)  WC-CoCr fails, cracks and delaminates under high compressive load (R=-1)  0.003” coating, failure at 180 ksi and above  0.010” coating, failure at 125 ksi and above (note that thicker coating carries more load)  cracks grow down from coating surface and often run parallel to interface (similar mechanism to that designed into composites)  cracks do not appear to propagate from coating into substrate Surfaces of WC-CoCr fatigue specimens from Southwest Aeroservice also show crack pattern and some spalling at failure and runout This shows there may be operational limits of WC-CoCr

29. Keith Legg 847-680-9420 Where should we be testing? What are the real-world requirements? What are the functional limits of WC-CoCr and WC-Co? Questions:

30. Keith Legg 847-680-9420 Bend test of Praxair WC-CoCr. Reported by Jay Randolph, Delta Airlines, July 1998 Fatigue and cracking - historical Fracture data - John Quets, Shane Arthur  WC-Co initially designed using bend test cracking data  WC-CoCr designed to have better corrosion performance, but lower fracture strength  So, WC composite coatings balance hardness and wear resistance against brittleness (fracture strength) 1998 - Crack-like indications found by FPI on aft side of WC-CoCr- coated Lufthansa landing gear. Barkhausen analysis by Boeing showed no crack propagation into steel. Returned to service - no reported problems.

31. Keith Legg 847-680-9420 Landing gear design and fatigue testing Designers do not design to specimen test data  Coupons provide stress engineers the data to start analyzing for customer and air-worthiness justification  Difficult to translate from load on full scale item to stress on test coupon  Qualification always depends on full-scale item fatigue testing under spectrum loading to 2 or 4 lifetimes Bulk of public domain data for AerMet 100 was run at 150 ksi or less (Roger Eybel)  a few points were run higher for interest sake

32. Keith Legg 847-680-9420 Fatigue - Loads on Landing Gear

33. Keith Legg 847-680-9420 Fatigue - Loads on Landing Gear Makes no sense to test coatings above levels used in full rig tests Looks as though we have the following maximum needs:  Commercial 170 ksi, R=0.1  Military, typical 180 ksi, R=-1  Military, high performance 240 ksi, R=-1 Questions:  At what loads/cycles were F-18 landing gear qualified?  Do you really go to yield thousands of times?

34. Keith Legg 847-680-9420 Summary of major ongoing work Corrosion  Additional tests planned  samples made Fatigue  C-HCAT testing 0.003” WC- CoCr below 180 ksi  Rethinking tests for 0.010” WC-CoCr  Comparative testing with SW Aero WC-CoCr and WC-Co Embrittlement  Environmental embritt. Ball impact - in progress Producibility testing  Heroux - grinding, stripping, NDI, fluids, etc. Rig testing  BFG, Messier-Dowty Flight testing  NADEP-JAX P3  DND CC-130

35. Keith Legg 847-680-9420 Remaining issues being resolved US-HCAT corrosion testing to be redone  obviously testing problem Fatigue testing  Not a structural issue that will cause failure, but a functional issue that will impose limits  Clearly define fatigue limits and requirements  Understand strain-to-failure, fatigue, residual stress relationships  Definition of load/thickness limits for WC-Co as done for WC- CoCr  WC-CoCr with hourglass specimens to define S/N curve comparable with WC-Co per JTP?

36. Keith Legg 847-680-9420 Where does qualification look good? Commercial  no brainer - in production Military - general  likely to work with WC-Co  may be near edge of envelope for WC-CoCr High performance military (primarily fighters)  need to define operational loads carefully to match qual of existing gear  may need lower hardness, higher toughness material Full article tests - rig, flight

37. Keith Legg 847-680-9420 Remaining issues US-HCAT corrosion testing to be redone  obviously testing problem Fatigue testing of WC-CoCr with hourglass specimens  define S/N curve comparable with WC-Co per JTP Definition of load/thickness limits for WC-Co  as done for WC-CoCr