Appendix 2 133
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
2. Select all mechanical, metallurgical, and physical properties of the part affected by the repair design, and assess their impact on the part’s airworthiness:
Mechanical Properties:
a. Stress-Strain
b. Fracture Toughness
c. Fatigue Strength (S-N, Goodman, dwell time)
d. Creep
e. Tensile Properties (yield, strength, elongation)
f. Hardness
g. Young’s Modulus
h. Natural Frequencies
Metallurgical Properties:
i. Chemical Composition (alloy constituents)
j. Microstructure (grain size – shape - boundary precipitates, gamma prime size and volume fraction, etc.)
k. Melting Point
l. Corrosion Resistance
m. Oxidation Resistance
n. Wear Resistance (consider wear types in (1)(e))
o. Crack Propagation Rate
Physical Properties:
p. Density (weight)
q. Coefficient of Thermal Expansion
r. Refractive Index (X-Rays)
s. Center of Gravity
t. Polar Moment of Inertia
Appendix 2 134
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
3. Select all Material Properties/Characteristics for weldments or brazed joints that apply and evaluate them and their interface with the parent metal. The effect of any changes to the part’s metallurgy as a result of welds or braze, should be evaluated for airworthiness.
a. Microstructure (grain size, grain shape, grain boundary precipitates, gamma prime size and volume fraction, etc.)
b. Porosity (weldment)
c. Diffusion Zone (brazing)
d. Heat Affected Zone (welding)
4. Select all Coating Properties/Characteristics that apply and evaluate them and their interface with the parent metal. The effect of any changes to the part’s physical and operational capability as a result of the coating should be evaluated for airworthiness.
a. Coating Material Composition
b. Thickness, Coverage & Uniformity
c. Coating and Diffusion Zone Microstructure
d. Coating Hardness
e. Sintering
f. Strip Requirements/Process
g. Residual Stress
h. Resistance to Spalling
i. Thermal Resistance (coefficient of thermal expansion for the coating)
j. Erosion Resistance
k. Bonding (interface contamination)
l. Hydrogen Embrittlement (plating)
m. Compatibility with Base Material/Other Coatings
Appendix 2 135
CATEGORIES OF REPAIR Req No.
Repair Properties and Requirements to be Identified and Substantiated.
5. Select Surface Treatment that applies (Without Material Removal) and evaluate effect(s), if any, on airworthiness:
a. Burnishing
b. Peening
c. Butterfly Polish
d. Mass Media Finishing
6. Evaluate any degradation in the part’s function or durability due to the following processes, when applicable, and assess its impact, if any, on existing ICAs.
a. Machining, Milling, Broaching, or Grinding
b. Non-traditional Machining
c. Welding, Brazing or Coating
d. Straightening, Re-twisting, Reforming
e. Blending
f. Honing
g. Lapping
h. Grit Blast
i. Stripping
j. Cleaning (chemical, power flash, ultrasonic)
k. Residual Plating, Stripping, or Cleaning Agents
l. Stress Intensity Factor (Kt)
m. Heat Treatment (time, temp, atmosphere, etc.)
n. Plating
o. Dimensional Short-falls
p. Repetitive or Conflicting Repairs Contamination
7. Establish the Applicability of the Repair and the Repair Processing Sequence or evaluate any changes to an existing repair sequence for potential impact on the airworthiness of the part.
8. Select all that may be potentially affected by the repair design and evaluate system effect(s):
a. Structural Strength, including major load paths
b. Heat Transfer
c. Secondary Airflow
d. Aerodynamics
e. Weight
f. Center of Gravity
g. Moment of Weight
Appendix 2 136
CATEGORIES OF REPAIR Req No.
Repair Properties and Requirements to be Identified and Substantiated.
8 Critical Measurable Characteristics
9. Establish Measurable Characteristics and the allowable tolerances for the repaired part features and for any replacement detail(s) and give due consideration to mating part(s):
a. Surface finish/texture
b. Shotpeen intensity/coverage
c. Bearing bore dimensions and location characteristics
d. Pressure strength test
e. Flow capacity test
f. Dimensions, including heat distortion effects
1) Roundness
2) Flatness
3) Parallelism
4) Concentricity
5) True Position Tolerances
6) Edge Distance
7) Requirements
8) Finish Dimensions Requirements
Critical Measurable Characteristics
10. Coating Coverage Definition:
a. No Grit Blast
b. No coating in Filet Radii
11. Blend Area Proximity Limits Defined Repair Process Capability Technical Substantiation Requirements
12. Technical Plan with Significant Operations Identified
13. Process Demonstration (including variability requirements)
14. Part Demonstration/Inspection
15. Manufacturing requirements for fabrication of repair details or replacement sections used to accomplish repair:
Drawings/Specifications Quality Requirements Source Substantiation Requirements
Appendix 2 137
CATEGORIES OF REPAIR Req No.
Repair Properties and Requirements to be Identified and Substantiated.
8 Applicable 14 CFR Part 33 Requirements Subpart A – General
16. 33.4 Instructions for Continuous Airworthiness (ICA's)
17. 33.5 Instruction manual for installing and operating the engine
18. 33.7 Engine ratings and operating limitations
19. 33.8 Selection of engine power and thrust ratings
Applicable 14 CFR Part 33 Requirements Subpart B – Design and Construction;
General
20. 33.14 Start-stop cyclic stress (low cycle fatigue)
21. 33.15 Materials
22. 33.17 Fire prevention
23. 33.19 Durability (Note that 33.19 is associated with 33.27; 33.63; 33.83; 33.87; 33.88; and
33.90)
24. 33.21 Engine cooling
25. 33.23 Engine mounting attachments and structure
26. 33.25 Accessory attachments
27. 33.27 Turbine, compressor, fan, and turbosupercharger rotors
28. 33.28 Electrical and electronic control systems
29. 33.29 Instrument connection Subpart E – Design and Construction;
Turbine Aircraft Engines
30. 33.62 Stress analysis
31. 33.63 Vibration
32. 33.65 Surge and stall characteristics (Note 2)
33. 33.66 Bleed air system
34. 33.67 Fuel system
35. 33.68 Induction system icing (operability aspects) (Note 2)
36. 33.69 Ignitions system
37. 33.71 Lubrication system
38. 33.72 Hydraulic actuating systems
39. 33.73 Power or thrust response
40. 33.74 Continued rotation
41. 33.75 Safety analysis
Appendix 2 138
CATEGORIES OF REPAIR Req No.
Repair Properties and Requirements to be Identified and Substantiated.
8 Subpart E – Design and Construction;
Turbine Aircraft Engines
42. 33.76 Bird ingestion (operability aspects of ingestion)
43. 33.77 Foreign object ingestion—ice (operability aspects of ingestion)
44. 33.78 Rain and hail ingestion
45. 33.79 Fuel burning thrust augmentor Subpart F – Block Tests; Turbine Aircraft Engines
46. 33.83 Vibration tests
47. 33.85 Calibration tests
48. 33.87 Endurance tests
49. 33.88 Engine overtemperature test
50. 33.89 Operation test (Note 2)
51. 33.90 Initial maintenance inspection
52. 33.91 Engine component tests (HCF/LCF bench testing)
53. 33.92 Rotor locking tests
54. 33.93 Teardown inspection
55. 33.94 Blade containment and rotor unbalance tests (Weight changes)
56. 33.95 Engine-propeller system tests
57. 33.96 Engine tests in auxiliary power unit (APU) mode
58. 33.97 Thrust reversers
59. 33.99 General conduct of block tests Part 33 -Appendix A – Instructions for Continued Airworthiness
Part 33 -Appendix B- Certification Standard Atmospheric Concentrations of Rain and Hail
Part 34 – Exhaust Emissions
Appendix 2 139 Template 14
REPAIR SUBSTANTIATION CHECKLIST - STATIC STRUCTURE PART FAMILY (Ducts, Bearing Housings, Etc.)
Categories of Static Structure Parts Family Repairs. Determine which repair description best fits the repair proposal based. If no repair description is appropriate, contact the FAA Advisor for guidance.
CATEGORIES OF
REPAIRS
REPAIR DESCRIPTION
1. Blend Repair
2. Weld/Braze Repairs Excludes Detail Part Replacement
3. Weld/Braze Repairs Includes Detail Part Replacement
4. Assembly and/or Disassembly This repair removes and replaces detail parts without the use of permanent attachment.
Techniques, i.e., welded or brazed, assembly is either bolted or riveted.
5. Dimensional Restoration Coating or Plating
6. Straightening, Re-twist or Reforming Repair This repair includes dent repair.
Appendix 2 140
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
1. Applicable Degradation Modes:
Select all that apply based on the function of the part and its operating environment in the engine. This section provides the background for establishing the substantiation requirements.
a. Thermo-mechanical fatigue
b. Oxidation
c. Corrosion
d. Elevated temperatureinduced changes (creep, diffusion, ageing, temperature gradients)
e. Wear due to: adhesion, abrasion, corrosion, erosion, cavitation, fretting, oxidation
f. High-cycle fatigue
g. Rubbing, foreign object impact damage, O3 chemical attack, etc.
Appendix 2 141
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
2. Select all mechanical, metallurgical, and physical properties of the part affected by the repair design, and assess their impact on the part’s airworthiness:
Mechanical Properties:
a. Stress-Strain
b. Fracture Toughness
c. Fatigue Strength (S-N, Goodman, Dwell Time)
d. Creep
e. Tensile Properties (yield, strength, elongation)
f. Hardness
g. Young’s Modulus
h. Natural Frequencies
Metallurgical Properties:
i. Chemical Composition (alloy constituents)
j. Microstructure (grain size – shape - boundary precipitates, gamma prime size and volume fraction, etc.)
k. Melting Point
l. Corrosion Resistance
m. Oxidation Resistance
n. Wear Resistance (consider wear types in (1)(e))
o. Crack Propagation Rate
Physical Properties:
p. Density (weight)
q. Coefficient of Thermal Expansion
r. Refractive Index (X-Rays)
s. Center of Gravity
t. Polar Moment of Inertia
Appendix 2 142
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
3. Select all Material Properties/Characteristics for weldments or brazed joints that apply and evaluate them and their interface with the parent metal. The effect of any changes to the part’s metallurgy as a result of welds or braze should be evaluated for airworthiness.
a. Microstructure (grain size, grain shape, grain boundary precipitates, gamma prime size and volume fraction, etc.)
b. Porosity (weldment)
c. Diffusion Zone (brazing)
d. Heat Affected Zone (welding)
Appendix 2 143
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated. Repair Properties and Requirements to be Identified and Substantiated.
4. Select all Coating Properties/Characteristics that apply and evaluate them and their interface with the parent metal. The effect of any changes to the part’s physical and operational capability, as a result of the coating, should be evaluated for airworthiness.
a. Coating Material Composition
b. Thickness, Coverage & Uniformity
c. Coating and Diffusion Zone Microstructure
d. Coating Hardness
e. Sintering
f. Strip Requirements/Process
g. Residual Stress
h. Resistance to Spalling
i. Thermal Resistance (coefficient of thermal expansion for the coating)
j. Erosion Resistance
k. Bonding (interface contamination)
l. Hydrogen Embrittlement (Plating)
m. Compatibility with Base Material/Other Coatings
Material Properties/Degradation Modes/Product Qualities/etc. Technical Substantiation Requirements
5. Select Surface Treatment that applies (Without Material Removal) and evaluate effect(s), if any, on airworthiness:
a. Burnishing
b. Peening
c. Butterfly Polish
d. Mass Media Finishing
Appendix 2 144
CATEGORIES OF REPAIR Req No Repair Properties & Requirement to be Identified and Substantiated.
6. Evaluate any degradation in the part’s function or durability due to the following processes, when applicable, and assess its impact, if any, on existing ICAs.
a. Machining, Milling, Broaching, or Grinding
b. Non-traditional Machining
c. Welding, Brazing or Coating
d. Straightening, Re-twisting, Re-forming
e. Blending
f. Honing
g. Lapping
h. Grit Blast
i. Stripping
j. Cleaning (Chemical, power flash, Ultrasonic)
k. Residual Plating, Stripping, or Cleaning Agents
l. Stress Intensity Factor (Kt)
m. Heat Treatment (time, temp, atmosphere, etc.)
n. Plating
o. Dimensional Short-falls
p. Repetitive or Conflicting Repairs Contamination
7. Cleaning Properties, Characteristics & Material Property Debits:
a. Chemical (solutions, etc.)
b. Grit Blast (,pressure media etc.)
c. Power Flush (pressure, solution time, temp, etc.)
d. Ultrasonic (solution frequency, time, etc.)
e. Furnace (time, temp, atmosphere, etc.)