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 weight
• Excessive loading on retaining features
• Acceptable weight
• Acceptable stresses
• Hot/cold oil distress 3-3 Mechanical /metallurgical properties
• Modulus
• Forging grain flow angles
• Tensile, UTS, YS, elongation, stress rupture, creep, LCF, HCF
• Sudden overload properties
• Surface hardness depth
• Surface hardness
• Undesirable natural frequencies
• Low material properties
• Spalling during operation
• Acceptable stresses and frequencies
• Forging grain flow as required
• Adequate material properties
• Operational effects accounted for
• Impact testing 3-4 Environmental resistance
• Oxidation, corrosion, fretting resistance
• Elevated temperature stress relaxation
• Surface plating
• Spalling from oxidation/corrosion pitting
• Property reduction due to extreme oil overtemp or lack of cooling oil
• 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 Raw material processing • Inclusions and porosity
• Micro structural characteristics
• Crack growth from inclusion or porosity
• Inadequate material properties
• Process control (melt control, cleanliness
• Process control and sequencing 4-2 Heat treatment • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere
• Tooling and fixturing
• Incorrect structure leading to low material properties
• Process control and sequencing 4-3 Surface treatment • Plating • Improper thickness and coverage • Process control 4-4 Peening • Intensity
• Coverage
• Incorrect compressive stress, cracking • Process control 4-5 Surface hardening • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere
• Tooling and fixturing
• Improper case depth
• Hardness improper
• Process control 85
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 4-6 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 4-7 Non-destructive testing (NDT)
• Acceptance limits
• Sensitivity
• Cracking from excessive defect size • Verify part is tolerant to allowable defects 4-8 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” • Verify adequate control of processes and parameters 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 • Torque loads
• Oil temperatures
• Speeds
• Transient loads
• Axial/radial loads
• Inadequate part life due to analysis under-predicting part temperature, mechanical stress
• Perform analysis at relevant operating conditions 5-2 LCF life assessment • Temperature effects
• Overloads
• FOD impact
• 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
• Resonant vibration, cracking • Use applicable properties and Goodman diagram 5-4 Fracture mechanics • Temperature effects
• Threshold stress intensity
• Crack growth from defect • Use applicable dA/dN curve
• Predict K using expected defect size 5-5 Variation • Engine operation characteristics • Inadequate part life due to variation • Verify part is tolerant to variation 5-6 Life calculation • Predicted stress and temperature
• Material properties
• Operation during part life
• Inadequate part life due to analysis under-predicting • Verify correct inputs to lifing process 86
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
• Tensile strength
• Spalling
• Engine vibration response
• Microstructure
• Bearing surface breakdown • Perform adequate component and/or engine testing 6-2 Operability and performance
• Vibration signature
• Abnormal wear
• Maximum pad loading
• Excessive vibration
• Metal particles in oil
• Excessive oil temperature
• 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 for oil analysis
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 87
Appendix 2 Subpart B – Design and Construction;
General
5. 33.14 Start-stop cyclic stress (low cycle fatigue)
6. 33.15 Materials Could be affected
7. 33.17 Fire prevention
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
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
16. 33.63 Vibration Could be affected Bearing vibration-Design
17. 33.65 Surge and stall characteristics
18. 33.66 Bleed air systems
19. 33.67 Fuel system
20. 33.68 Induction system icing (Operability aspects)
21. 33.69 Ignition system
22. 33.71 Lubrication system
23. 33.72 Hydraulic actuating system
24. 33.73 Power or thrust response
25. 33.74 Continued rotation Could be affected Continued integrity
26. 33.75 Safety analysis Could be affected Bearing/Gear/Shaft release 88
Appendix 2 Subpart E – Design and Construction;
Turbine Aircraft Engines
27. 33.76 Bird ingestion (Operability aspects of ingestion) Could be affected Sudden bearing axial/radial loading
28. 33.77 Foreign object ingestion (Operability aspects of ingestion) Could be affected Sudden bearing axial/radial loading
29. 33.78 Rain hail ingestion
30. 33.79 Fuel burning thrust augmenter Subpart F – Block Tests; Turbine Aircraft Engines
31. 33.83 Vibration test Could be affected Bearing vibration
32. 33.85 Calibration tests
33. 33.87 Endurance test Could be affected Bearing durability
34. 33.88 Engine over temperature test
35. 33.89 Operation test
36. 33.90 Initial maintenance inspection Could be affected Bearing in-service inspection limits
37. 33.91 Engine component tests
38. 33.92 Rotor locking tests
39. 33.93 Teardown inspection Could be affected Bearing wear must be within serviceable limits
40. 33.94 Blade containment and rotor unbalance tests (Weight changes)
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 89
Gear TeethRim Bearing Mount Lightening Holes Hub Web AC 33-8 8/19/09 Appendix 2 Template #10: Gear Bearing Stop Threaded Retention Feature Nomenclature for Generic Component Features (all features may not be applicable) 90
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
• Bearing loading
• Inertia
• Surface dimensional process control 1-2 Gear tooth geometry • Number of teeth
• Gear tooth form
• Surface finish
• Surface hardness
• Correct speed
• Heat generation
• Metal generation
• Dimensional control
• Machining process control 1-3 Vibration characteristics (HCF capability)
• Gear natural frequencies
• Vibration stress distribution
• Cycles to failure demonstration
• Vibration test
• Gear resonant vibration, cracking • 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
• Tooth/web geometry
• Material mechanical/metallurgical/physical properties
• Tooth separation from overload
• Crack growth from LCF, HCF, or HCF/LCF interaction
• Verify capability exceeds expected duty cycle for highest load application 1-5 Bearing attachment • Surface finish
• Press fit
• Retaining thread
• Wear resistance on mating component
• Surface fret
• Metal contamination
• Bearing spinning
• Surface dimensional process control
• Verify acceptable wear 1-6 Weight reduction • Hole size and location
• Distance from hub and rim
• Surface finish
• Excessive tip cracking or corner loss • Surface dimensional process control 91
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 Tooth form • Shape
• Surface finish
• Pitch diameter
• Contact angle
• Edge break
• Tolerance
• Unbalance loading
• Vibration
• End loading
• Scuffing
• Dimensional process control and inspection 2-2 Gear rim • Width
• Height
• Width: proper transition radius
• Height: enough mass to control deformation
• Rim resonant vibration, cracking, dysfunction
• Dimensional process control 2-3 Web • Transition to rim and hub
• Thickness distribution
• Lightning features
• Dampening features
• Gear vibratory mode changes due to thickness distribution
• Weight – excessive inertia load
• Stress/life
• Surface dimensional process control 2-4 Hub • Bearing fit
• Axial location of gear surface
• Proper bearing preload
• Correct gear alignment
• Dimensional process control 2-5 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 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 • Excessive weight • Acceptable gear weight
• Coefficient of thermal expansion • Excessive loading on retaining features • Acceptable stresses
• Melting point • Hot/cold oil distress 3-3 Mechanical /metallurgical properties
• Modulus
• Forging grain flow angles
• Tensile, UTS, YS, elongation, stress rupture, creep, LCF, HCF
• Sudden overload properties
• Surface hardness depth
• Undesirable natural frequencies
• Low material properties: tooth, rim separation
• Spalling during operation
• Acceptable stresses & frequencies
• Forging grain flow as required
• Adequate material properties
• Operational effects accounted for
• Impact testing 92
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 3-4 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, vibration,
• Verify that variations in grain structure are accounted for
• Process control and inspection 3-5 Environmental resistance
• Oxidation, corrosion, fretting resistance
• Elevated temperature stress relaxation
• Surface coating
• Spalling from oxidation/corrosion pitting
• Property reduction due to extreme oil overtemp or lack of cooling oil
• 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 Raw material processing • Inclusions and porosity
• Micro structural characteristics
• Crack growth from inclusion or porosity
• Inadequate material properties
• Process control (melt control, cleanliness
• Process control and sequencing 4-2 Heat treatment • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere
• Tooling and fixturing
• Incorrect structure leading to low material properties
• Process control and sequencing 4-3 Welding Effect on base material properties, based on the following:
• Weld strength
• Microstructure: grain size, shape, flow, defects, grain boundary precipitates
• Porosity
• Heat affected zone
• Filler metal selection
• Joint design
• Material property reduction
• Weld failure
• Correct sequencing of weld process
• Process control 4-4 Peening • Intensity
• Coverage
• Incorrect compressive stress, cracking • Process control 4-5 Surface hardening • Time @ temperature and ramp rates
• Manufacturing sequence
• Atmosphere
• Tooling and fixturing
• Improper case depth
• Hardness improper
• Process control 93
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 4-6 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 4-7 Non-destructive testing (NDT)
• Acceptance limits
• Sensitivity
• Cracking from excessive defect size • Verify part is tolerant to allowable defects 4-8 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” • Verify adequate control of processes and parameters 4-9 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
• Process control and sequencing 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 • Torque loads
• Oil temperatures
• Speeds
• Transient loads
• Inadequate part life due to analysis under-predicting part temperature, mechanical stress
• Perform analysis at relevant operating conditions 5-2 LCF life assessment • Temperature effects
• Overloads
• FOD impact
• 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
• Resonant vibration, cracking, dysfunction • Use applicable properties and Goodman diagram 5-4 Fracture mechanics • Temperature effects
• Threshold stress intensity
• Crack growth from defect • Use applicable dA/dN curve
• Predict K using expected defect size 94
Appendix 2 Section 5 – Analysis Section/ Number Characteristic Critical to Part Functionality Key Characteristics Part and System Failure Modes Risk Mitigation and Control 5-6 Variation • Engine operation characteristics
• Inadequate part life due to variation • Verify part is tolerant to variation 5-7 Life calculation • Predicted stress and Temperature
• Material properties
• Operation during part life
• Inadequate part life due to analysis under-predicting • Verify correct inputs to lifing process 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
• Tooth alignment
• Spalling
• Engine vibration response
• Microstructure
• Gear dysfunction • Perform adequate component and/or engine testing 6-2 Operability and performance
• Vibration signature
• Abnormal gear wear
• Maximum pad loading
• Excessive vibration
• Metal particles in oil
• Accessories not able to be fully loaded
• Engine testing 95
Appendix 2 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 Subpart B – Design and Construction;
General
5. 33.14 Start-stop cyclic stress (low cycle fatigue)
6. 33.15 Materials Could be affected
7. 33.17 Fire prevention
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
13. 33.28 Electrical and electronic control systems
14. 33.29 Instrumentation connection 96