Keith Legg Test Status Overview HCAT Program Review NASA, Florida Dec 13,14, 2000

Keith Legg 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

Keith Legg 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?

Keith Legg 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

Keith Legg Production use of HVOF WC-Co and WC-CoCr coatings

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

Keith Legg Production use of HVOF landing gear coatings - Messier-Dowty Note production use on high performance aircraft

Keith Legg Data summary: Landing Gear JTP - Coupon test data

Keith Legg Data summary: Propeller Hub JTP - Coupon test data

Keith Legg 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

Keith Legg 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

Keith Legg 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

Keith Legg 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)

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

Keith Legg Data summary: Landing Gear JTP - Rig and flight testing

Keith Legg Data summary: Propeller Hub JTP Rig and flight testing

Keith Legg 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

Keith Legg 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

Keith Legg 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 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

Keith Legg Data summary - Ancillary tests

Keith Legg 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

Keith Legg 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

Keith Legg 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

Keith Legg Fluid compatibility Under way shortly at Heroux Will include evaluations of hydrogen embrittlement due to fluids

Keith Legg 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?

Keith Legg 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)

Keith Legg Fatigue and fracture Fatigue of WC-CoCr - the picture folks took back from Ottawa meeting

Keith Legg 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

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

Keith Legg 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) 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.

Keith Legg 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

Keith Legg Fatigue - Loads on Landing Gear

Keith Legg 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?

Keith Legg 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

Keith Legg 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?

Keith Legg 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

Keith Legg 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