Appendix 2 Section 1 – Part Functional capability, i.e., the action(s) that the part is designed to perform in the product Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 1-1 Weight • As-forged surfaces
• Machined surfaces Dovetail and disk loading-dysfunction Surface dimensional process control 1-2 Moment of weight - center of gravity
• Axial
• Tangential
• Radial
• As-forged surfaces
• Machined surfaces
• Mass/density distribution Dovetail and disk loading-dysfunction Surface dimensional process control 1-3 Vibration characteristics (HCF capability)
• Blade natural frequencies
• Vibration stress distribution
• Cycles to failure demonstration
• Vibration test set-up and execution criteria, i.e., establishing parameters for blade holding, loading, excitation modes determination, and excitation sensing techniques Blade resonant vibration, cracking, dysfunction • Resonance avoidance at steady state operation with margin
• Vibratory and steady state stress within Goodman Diagram limits 1-4 LCF, fracture toughness, tensile overload capability
• Blade geometry
• Material mechanical/metallurgical/physical properties
• Blade separation from tensile overload
• Crack growth from LCF, HCF, or HCF/LCF interaction
• Loss of tip fatigue strength from rubbing Verify capability exceeds expected utilization 1-5 Part span shrouds • Shroud geometry
• Shroud location on airfoil
• Wear resistance on mating component
• Blade vibration: airfoil cracking
• Blade dysfunction during FOD event
• Surface dimensional process control
• Verify acceptable wear couple 1-6 Squealer tip • Squealer tip geometry • Excessive rub load
• Tip cracking or corner loss Surface dimensional process control 109
Appendix 2 Section 2 – Part Shape, size, dimensions and other physical measurable parameters, and interconnectivity with an engine integral part/system Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 2-1 Dovetail • Shape
• Surface contour
• Tang relative location and taper
• Tolerance (blade root and disk slot dimensional spectrums and blade producibility limitations)
• Unbalance tang loading/blade dysfunction
• Incorrect loading on disk/cracking Dimensional process control and inspection 2-2 Platform • Width
• Length
• Inner gas path contour
• Width: binding, recirculation
• Length: rotor/stator rubs
• Platform resonant vibration, cracking, dysfunction Dimensional process control 2-3 Airfoil external shape
• Aero contour/stagger angle
• Leading edge contour
• Thickness distribution
• Chord
• Poor aero performance
• Airfoil vibratory mode changes due to thickness distribution
• Operability issues – stall leading to lack of thrust and potential damage to flowpath hardware
• FOD tolerance
• Supply bleed pressure – insufficient mass flow to turbine blade and/or rotor cavity leading to turbine blade/rotor dysfunction
• Weight - Dovetail and disk loading-dysfunction
• Airfoil stress/life Surface dimensional process control 2-4 Tolerance • Variance-fluctuations in measurements
• Measurement gauge repeatability and reliability Mechanical/functional, failure due to variation from nominal • Verify part is tolerant to variation
• Control of manufacturing and inspection processes 2-5 Airfoil to platform filets
• Filet profile Failure due to stress concentration • Dimensional process control 110
Appendix 2 Section 3 – Part Materials and Processes – Properties Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 3-1 Chemistry • Major elements - % variation
• Impurities
• Poor mechanical or environmental properties Material selection Process control 3-2 Physical properties • Density
• Coefficient of thermal expansion
• Melting point
• Excessive blade weight
• Interference with surrounding hardware Verify:
• Acceptable blade weight
• Acceptable stresses
• Blade “fit” in hot condition 3-3 Mechanical /metallurgical properties
• Modulus
• Forging grain flow angles
• Bare and coated: tensile (UTS, YS, elongation, stress rupture, creep, LCF, HCF)
• Long term metallurgical stability
• Impact properties
• Undesirable natural frequencies
• Low material properties, blade dysfunction
• Material capability consumed in operation Verify:
• Acceptable stresses and frequencies
• Forging grain flow as required
• Adequate material properties
• Operational effects accounted for
• Impact testing 3-4 Forged structure • Grain structure (size, shape, flow, boundaries)
• Directional properties
• Hardness
• Forging laps
• Homogeneity of forging work throughout part Material property reduction due to abnormal grain structure, blade dysfunction Verify that variations in grain structure are accounted for Process control and inspection 3-5 Environmental resistance
• Oxidation, corrosion, erosion, fretting resistance
• Elevated temperature stress relaxation, alpha case formation)
• Rubbing, FOD resistance
• Cracking from oxidation/corrosion pitting, blade dysfunction
• Property reduction due to brittle Alpha case, blade dysfunction Verify adequate environmental and wear properties 3-6 Environmental coating
• Coverage and thickness
• Long term stability
• Corrosion resistance Cracking from corrosion pitting Control of chemistry and application process Verify thermal-mechanical compatibility with base material 3-7 Ti Fire resistance • Rub rate (clearances, relative motion)
• Environment (temperature, pressure)
• Material of adjacent hardware 3-8 Dovetail anti-fret coating
• Wear resistance and abrasiveness
• Coverage and thickness
• Temperature capability
• Loss of material leading to dysfunction of blade and/or disk
• Unbalanced loading leading to dysfunction of blade and/or disk Verify acceptable wear couple Control of chemistry and application process Verify adequate temperature capability 3-9 Erosion coating • Erosion resistance
• Compatibility with base material
• Performance and operability degradation
• Blade dysfunction due to material property degradation Verify adequate erosion characteristics and base material compatibility 111
Appendix 2 Section 4 – Part Materials and Processes - Processing Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 4-1 Raw material processing • Inclusions and porosity
• Microstructural characteristics
• Crack growth from inclusion or porosity
• Inadequate material properties and blade dysfunction Process control (melt control, cleanliness) Process control and sequencing 4-2 Heat treatment • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere Incorrect structure leading to low material properties Process control and sequencing 4-3 Brazing Effect on base material properties, based on the following:
• Braze strength
• Microstructure (grain size, shape, flow, braze gap, defects, grain boundary precipitates)
• Porosity
• Diffusion zone (brazing)
• Excess braze allowance
• Filler metal selection
• Material property reduction
• Braze failure and loss of mid-span wear pad Correct sequencing of braze cycles in the process Process control 4-4 Peening • Intensity
• Coverage Incorrect dovetail compressive stress, cracking, and blade dysfunction Process control 4-5 Material removal – Non traditional (EDM, ECM, laser, water-jet, etc.)and conventional (machining, milling, broaching, grinding, blending, honing, lapping, stripping, etc.)
Micro cracks or recast:
• Inherent to the process
• Due to abusive machining Fatigue capability degradation, due to:
• Surface finish
• Stress risers
• Chemical attack Cracking initiation from micro-cracks or re-cast Verify part is tolerant to proposed limits Process control 4-6 Non-destructive testing (NDT)
• Acceptance limits
• Sensitivity Cracking from excessive defect size Verify part is tolerant to allowable defects 4-7 Process sequencing and significant process identification and Substantiation
• Inspection
• Manufacturing
• Process substantiation and control (RSS,RSA,ESA, etc) Inadequate final part form, or defect “escape”, blade dysfunction Verify adequate control of processes and parameters 4-8 Forging process Forging structure
• Grain Structure (size, shape, flow, boundaries)
• Directional properties
• Hardness
• Forging laps
• Homogeneity of forging work throughout part Material property reduction due to abnormal grain structure, blade dysfunction Process control and sequencing 112
Appendix 2 Section 5 – Analysis Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 5-1 Operating conditions • Flow path temperatures, pressures, and velocities
• Rotor speed Inadequate part life due to analysis under-predicting part temperature, mechanical stress Perform analysis at relevant operating conditions 5-2 LCF life assessment – airfoil and shank
• Temperature effects
• Hold time effects
• Mean stress effects
• Notch effects
• Coating effects
• Mesh size Inadequate part life due to analysis
• Using incorrect properties
• Failing to address the ‘key characteristics’
• Use applicable properties
• Select mesh size to correctly model the geometry 5-3 HCF life analysis • Temperature effects
• Vibration and mean stress effects Blade resonant vibration, cracking, dysfunction Use applicable properties and Goodman diagram 5-4 Creep and rupture life analysis
• Temperature effects
• Material thickness effects Blade rupture cracking, dysfunction Use applicable properties 5-5 Fracture mechanics • Temperature effects
• Threshold stress intensity Crack growth from defect • Use applicable dA/dN curve
• Predict K using expected defect size 5-6 Variation • Blade or engine characteristics Inadequate part life due to variation Verify part is tolerant to variation 5-7 Life calculation • Predicted stress and temperature
• Root loading profile shifts
• Material properties
• Operation during part life
• Life impact on disk Inadequate part life due to analysis under-predicting Verify correct inputs to lifing process 113
Appendix 2 Section 6 – Testing Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 6-1 Durability • Fatigue
• Corrosion (hot and cold)
• Erosion
• Creep
• Tensile strength
• Ballistic capability
• Engine Aeromechanical response
• Microstructure Blade dysfunction Perform adequate component and/or engine testing 6-2 Operability and Performance
• Stall margin
• Acceleration rates
• SFC
• Thrust
• Stall leading to lack of thrust and potential damage to flowpath hardware
• Unacceptable acceleration rate
• Unacceptable range and loading capability Engine testing Section 7 – Potential Impact on Regulatory Requirements Note: The regulatory requirements identified below, which are inclusive up to Amendment 20 of 14 CFR part 33, are intended as a guide to applicants when determining the applicable regulations to which they must show compliance. Those requirements listed as “Could be affected” highlight the regulations whose compliance findings are typically affected by the component or part that this template is addressing.
This guide is not all-inclusive and the applicant remains responsible for identifying the certification basis of the product on which their PMA part is to be installed.
Applicable 14 CFR Part 33 Regulatory Requirements Comments Subpart A – General
1. 33.4 Instructions for Continued Airworthiness Could be affected ICAs including on-wing inspection requirements and on-wing limits
2. 33.5 Instruction manual for installing and operating the engine
3. 33.7 Engine ratings and operating limitations
4. 33.8 Selection of engine power and thrust ratings 114
Appendix 2 Subpart B – Design and Construction;
General
5. 33.14 Start-stop cyclic stress (low cycle fatigue) Could be affected Weight and center-of-gravity affect on rotor forces and LCF capability
6. 33.15 Materials Could be affected
7. 33.17 Fire prevention Could be affected Titanium fire
8. 33.19 Durability Could be affected
9. 33.21 Engine cooling
10. 33.23 Engine mounting attachments and structure
11. 33.25 Accessory attachments
12. 33.27 Turbine, compressor, fan, and turbosupercharger rotors Could be affected Weight affect on rotor forces during over-speed
13. 33.28 Electrical and electronic control systems
14. 33.29 Instrumentation connection Subpart E – Design and Construction;
Turbine Aircraft Engines
15. 33.62 Stress analysis Could be affected Rotor stress analysis
16. 33.63 Vibration Could be affected Blade vibration-Design
17. 33.65 Surge and stall characteristics Could be affected Compressor stall line - Operating line migration due to erosion
18. 33.66 Bleed air systems Could be affected Pressure at bleed location
19. 33.67 Fuel system
20. 33.68 Induction system icing (Operability aspects) Could be affected Bleed temperature impacts icing system
21. 33.69 Ignition system
22. 33.71 Lubrication system
23. 33.72 Hydraulic actuating system
24. 33.73 Power or thrust response Could be affected Compressor efficiency/performance
25. 33.74 Continued rotation
26. 33.75 Safety analysis Could be affected Compressor blade release-Case containment 115
Appendix 2 Subpart E – Design and Construction;
Turbine Aircraft Engines
27. 33.76 Bird ingestion (Operability aspects of ingestion) Could be affected Compromised aero – missing airfoil
28. 33.77 Foreign object ingestion (Operability aspects of ingestion) Could be affected Compromised aero – missing airfoil
29. 33.78 Rain and hail ingestion
30. 33.79 Fuel burning thrust augmenter Subpart F – Block Tests; Turbine Aircraft Engines
31. 33.83 Vibration test Could be affected Blade vibration
32. 33.85 Calibration tests
33. 33.87 Endurance test Could be affected Blade durability
34. 33.88 Engine over temperature test
35. 33.89 Operation test
36. 33.90 Initial maintenance inspection Could be affected Blade in-service inspection limits
37. 33.91 Engine component tests
38. 33.92 Rotor locking tests
39. 33.93 Teardown inspection
40. 33.94 Blade containment and rotor unbalance tests (Weight changes) Could be affected Failure of the most critical compressor blade while operating at maximum permissible r.p.m.
41. 33.95 Engine-propeller system tests
42. 33.96 Engine tests in auxiliary power unit (APU) mode
43. 33.97 Thrust reversers
44. 33.99 General conduct of block tests
45. Part 33 - Appendix A – Instructions for Continued Airworthiness Could be affected
46. Part 33 - Appendix B - Certification Standard Atmospheric Concentrations of Rain and Hail 116
Appendix 2 Template #13: Static Air Seal Honeycomb/Rubber/Teflon on Sheet metal/Machined Forging
VIEW A BACKING
E VIEW A
END FACE
ND FACE SEE VIEW B HONEYCOMB BACKING STRIPS VIEW B
WEAR GROOVES HONEYCOMB BRAZE JOINT
HONEYCOMB
CELLS SECTION A-A
BACKING DETAIL A BACKING STRIP STRIP
RETAINER SEALS
• BRAZE JOINTS
HONEYCOMB
GROOVE SEE VIEW B
SEE DETAIL A
HONEYCOMB JONES
HONEYCOMB CELLS Nomenclature for Generic Component Features (all features may not be applicable) 117
Appendix 2 Section 1 – Part Functional capability, i.e., the action(s) that the part is designed to perform in the product Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 1-1 Tensile capability • Material mechanical/metallurgical/physical properties
• Seal failure. Excessive contact. Rotating part dysfunction Verify capability exceeds expected utilization 1-2 Abradability-solid • Material mechanical/physical properties
• Machinabilty by rotating seal teeth
• Environmental temperature capability
• Thermal instability. Rotating part dysfunction
• Rotating seal tooth cracking. Rotating part dysfunction
• Excessive seal wear/leakage Verify compatibility to rotating seal 1-3 Cutting characteristicshoneycomb
• Material mechanical/metallurgical/physical properties
• Machinabilty by rotating seal teeth
• Foil thickness. cell size. braze wicking
• Thermal instability. Rotating part dysfunction
• Rotating seal tooth cracking. Rotating part dysfunction
• Excessive seal wear/leakage Verify compatibility to rotating seal Section 2 – Part Shape, size, dimensions and other physical measurable parameters, and interconnectivity with an engine integral part/system Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 2-1 Tolerance • Variance-fluctuations in measurements
• Measurement gauge repeatability and reliability Mechanical/Functional, failure due to variation from nominal • Verify part is tolerant to variation
• Control of manufacturing and inspection processes 2-2 Retention/hook geometry
• Thickness
• Axial length
• Radius Excessive wear, looseness of fit, excessive seal clearance, performance impact
• Dimensional process control and inspection geometry 2-3 Anti-rotation feature • Location
• Bearing surface area
• Crimping Arch-binding, mechanical failure due to excessive seal rub, rotating part dysfunction
• Dimensional process control and inspection geometry 2-4 Honeycomb/ abradable geometry
• Inner diameter
• Cell depth Failure to seal, performance impact Excess rub, rotating part dysfunction Fatigue failure
• Dimensional process control and inspection geometry 2-5 Backing plate geometry
• Arc length
• Inner diameter Arch-binding, mechanical failure due to excessive seal rub, rotating part dysfunction
• Dimensional process control and inspection geometry 118
Appendix 2 Section 3 – Part Materials and Processes – Properties Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 3-1 Chemistry • Major elements - % Variation
• Impurities
• Poor mechanical or environmental properties Material selection 3-2 Physical properties • Thermal conductivity
• Coefficient of thermal expansion
• Interference with surrounding hardware Verify:
• Acceptable stresses
• Seal “fit” in hot condition 3-3 Mechanical properties
• Wrought structure
• Hardness/grain size
• Modulus
• Tensile (UTS, YS)
• Long term metallurgical stability
• Low material properties
• Material capability consumed in operation
• Low material properties, seal dysfunction Verify:
• Acceptable stresses
• Adequate material properties
• Operational effects accounted for
• Relevant properties are used 3-4 Environmental resistance
• Oxidation, corrosion, erosion, fretting resistance Cracking from oxidation/corrosion pitting, seal dysfunction Verify adequate environmental properties Section 4 – Part Materials and Processes - Processing Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 4-1 Heat treatment • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere Low material properties Process control and sequencing 4-2 Brazing Effect on base material properties, based on the following:
• Braze strength
• Microstructure, braze gap, defects, Porosity
• Diffusion zone (brazing)
• Excess braze allowance
• Filler metal selection Material property reduction, braze failure • Correct sequencing of braze cycles in the process
• Process control 4-3 Material removal – Non traditional (EDM, ECM, Laser, Water-Jet) and conventional (machining, milling, broaching, grinding, blending, honing, lapping, stripping) Micro cracks or recast:
• Inherent to the process
• Due to abusive machining Fatigue capability degradation, due to:
• Surface finish
• Stress risers
• Chemical attack Cracking initiation from micro-cracks or re-cast • Verify part is tolerant to proposed limits
• Process control 4-4 Non-destructive testing (NDT)
• Acceptance limits
• Sensitivity Cracking from excessive defect size Verify part is tolerant to allowable defects 4-5 Process sequencing and significant process identification and substantiation
• Inspection
• Manufacturing
• Process substantiation and control (RSS,RSA,ESA, etc) Inadequate final part form, or defect “escape”, seal dysfunction Verify adequate control of processes and parameters 119
Appendix 2 Section 5 – Analysis Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 5-1 Operating conditions • Cavity temperatures, pressures, Inadequate part life due to analysis under-predicting part temperature, thermal or mechanical stress Perform analysis at relevant operating conditions 5-2 Variation • Dimensional characteristics Inadequate part life Verify part is tolerant variation 5-3 Life calculation • Calculated stress and Temperature
• Material properties
• Operating during part life Inadequate part life due to analysis under-predicting Verify correct inputs to life calculation Section 6 – Testing Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 6-1 Durability • Fatigue
• Tensile strength
• Cleaning requirements 6-2 Bond Strength 120