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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
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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)
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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
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
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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, 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
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Repair Properties and Requirements to be Identified and Substantiated.
8 Critical Measurable Characteristics
9. Cooling (Total flow, flow split, back flow margin, hole exit geometry/angle/location, cross over hole size, metering plate)
10. Dimension of sealing features (leakage, secondary circuits)
11. 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 Roundness Flatness Parallelism Concentricity True Position Tolerances Edge Distance Requirements Finish Dimensions Requirements
g. Airfoils Profile Leading and Trailing Edge Contour Concave and convex contours Thickness Chord and Airfoil Length Twist/Lean/Bow
h. Tip Length
i. Airfoil wall thickness
j. Throat Area
Repair Process Capability Technical Substantiation Requirements
12. Verification Plan with Significant Operations Identified for Repair Source Qualification
13. Process Demonstration (including variability requirements)
14. Part Demonstration/Inspection
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Repair Properties and Requirements to be Identified and Substantiated.
8 Repair Process Capability Technical Substantiation Requirements
15. Manufacturing requirements for fabrication of repair details or replacement sections used to accomplish repair:
Drawings/Specifications Quality Requirements Source Substantiation Requirements
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
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
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Repair Properties and Requirements to be Identified and Substantiated.
8 Subpart B – Design and Construction;
General
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 systems
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
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
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Repair Properties and Requirements to be Identified and Substantiated.
8 Subpart F – Block Tests; Turbine Aircraft Engines
46. 33.83 Vibration test
47. 33.85 Calibration tests
48. 33.87 Endurance test
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