Appendix 2 13 APPENDIX 2. SAMPLE TEMPLATES
1. Purpose. This appendix includes templates for major repairs related to 17 engine part families, listed in Table A2-1 below. The FAA selected them based on typical repairs for complex turbine engine parts submitted as major. These templates will aid repair developers in identifying the technical elements and regulatory requirements they should consider when developing and substantiating similar major repairs. Persons developing data must ensure that any additional technical criteria or regulatory requirements are met for their specific proposed major repair.
2. Template Instructions. Each template shows both shaded and un-shaded (clear) cells corresponding to the sample repair and its specific engineering, technical and regulatory considerations. Those cells that are generally applicable are un-shaded. However, the repair developer must decide if the cells need to be completed or not. The templates identify the current part 33 regulations, Amendments 1-20 inclusive, applicable to turbine engines as an example. When reviewing the associated regulatory considerations, the repair developer should determine applicability and identify the corresponding methods of compliance to be used to provide the supporting data.
a. The certification basis of the engine(s) on which the repaired part is eligible for installation identifies the regulatory requirements that should be reviewed for applicability.
Applicable regulations are those regulations that must be evaluated to determine that the engine remains in compliance and airworthy with respect to the repair work performed. For critical and complex parts, the repair developer should determine which of the original compliance findings to those applicable regulations could be affected by their proposed major repair. To do this, you must understand how the part to be repaired functions in the engine operating environment, and the associated regulatory requirements. Repair developers substantiate their repair to these requirements, using acceptable methods, to show that the condition of the engine on which the repaired part is installed will be at least equal to its original or properly altered condition.
b. Acceptable methods are identified as follows:
(1) D - Documentation (for example, Instructions for Continued Airworthiness).
(2) A - Analysis of relevant data.
(3) I - Inspection (for example, metallurgical examination, hardness testing, Nondestructive testing inspection).
(4) R - Rig testing.
(5) C - Component testing.
(6) E - Engine testing.
Appendix 2 14
(7) S - Similarity to previously FAA approved data. Repair developers will need to show that the previously approved data is applicable to the new proposed repair, and to the product type design if different than the type design for which the data was previously approved.
3. Sample Templates. If a template is not available for a particular major repair, the repair developer can create or modify another as necessary.
Table A2-1. Sample Templates.
Template Number Title Page 1 Bearing Compartment and Carbon Seal Parts Family 15 2 High Pressure Turbine (HPT) Blade Part Family 25 3 Low Pressure Compressor (LPC) – High Pressure Compressor (HPC) Blade Part Family 36 4 Blades – Low Pressure Turbine (LPT) 46 5 Combustor Part Family 55 6 Externals Part Family (Tubes, Manifolds, Ducts, Brackets) 66 7 Fuel Nozzle Part Family 75 8 Gearbox Housing Assembly Part Family (Shafts, Gears, Housings) 84 9 Low Pressure Compressor (LPC) – High Pressure Compressor (HPC) Stator Part Family – Vane Sector (And Full Ring) Type Stators 94 10 Low Pressure Compressor (LPC) – High Presser Compressor (HPC) Stator Part Family – Fixed Vane Type Stators 103 11 Major Engine Cases 112 12 Major Rotating (Non-Life Limited) Part Family (Excluding Turbine Shaft Coupling Part Family) 121 13 High Pressure Compressor (HPC)/High Pressure Turbine (HPT)/Low Pressure Turbine (LPT) Airseals (Non-Rotating) And Shrouds (Stationary) Part Family 130 14 Static Structure Part Family (ducts, bearing housings, etc.)
138 15 Low Pressure Compressor (LPC) – High Pressure Compressor (HPC) Stator Part Family – Variable Vane Type Stators 148 16 HPT Vane Part Family 157
Appendix 2 15 17 Low Pressure Turbine (LPT) Vane Part Family 166
Appendix 2 16 Template 1
REPAIR SUBSTANTIATION CHECKLIST - BEARING COMPARTMENT AND
CARBON SEAL PART FAMILIES
Categories of Bearing Compartment & Carbon Seal Part Family Repair. Determine which repair description best fits the repair proposal. If no repair description is appropriate, contact the FAA Advisor for guidance.
CATEGORIES OF
REPAIRS
REPAIR DESCRIPTION
1. Restoration of Protective Coating This repair includes touch-up coating
2. Weld or Braze Repair This repair excludes detail part replacement
3. Weld or Braze Repair This repair includes detail part replacement
4. Assembly and/or Disassembly This repair assembles, disassembles, removes and replaces detail parts, or s ubassemblies without use of permanent attachment techniques (i.e.; welding or brazing). Assembly is either bolted or riveted.
5. Blend Repair
6. Dimensional Restoration by Coating or Plating
7. Bushing/Helicoil Repair
8. Straightening, Re-twist, or Reforming Repair This repair includes straightening of bent knife edges
9. Surface Treatment Repair This repair includes peening, vibratory tumble (e.g.; restoration of surface finish/texture)
10. Machining Repair This repair includes lapping, skim cut, non-conventional machining.
11. Restoration of Adhesives, Bonding Agents, Potting Compound
When the cell under a category of repair is not shaded, the items listed under that requirement should be reviewed for applicability, based on the repair design, and only the items pertinent to this category of repair should be selected and addressed appropriately. Items not selected need not be addressed.
An FAA-approved configuration means a new part (produced under a PC, TSO, or PMA) or a previously approved repaired part.
Appendix 2 17
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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 Temperature- Induced 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 18
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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 19
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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 20
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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
Appendix 2 21
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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
q. Contamination
Appendix 2 22
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
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
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):
Surface finish/texture Shotpeen Intensity/Coverage Bearing bore dimensions and location characteristics Pressure Strength Test Flow Capacity test Dimensions, including heat distortion effects
1) Roundness
2) Flatness
3) Parallelism
4) Concentricity
5) True Position Tolerances
6) Edge Distance Requirements
7) Finish Dimensions Requirements
10. Significant Operations Identified for Validation that would include parameter variability limits.
Appendix 2 23
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
11. Manufacturing requirements for fabrication of repair details or replacement sections used to accomplish repair:
Drawings/Specs Quality Requirements Critical Process Validation needs
Applicable 14 CFR Part 33 Requirements
Subpart A – General
12. 33.4 Instructions for Continuous Airworthiness (ICA's)
13. 33.5 Instruction manual for installing and operating the engine
14. 33.7 Engine ratings and operating limitations
15. 33.8 Selection of engine power and thrust ratings
Subpart B – Design and Construction; General
16. 33.14 Start-stop cyclic stress (low cycle fatigue)
17. 33.15 Materials
18. 33.17 Fire prevention
19. 33.19 Durability (Note that 33.19 is associated with 33.27; 33.63; 33.83;
33.87; 33.88; and 33.90)
Appendix 2 24
CATEGORIES OF REPAIR Req No.
Repair Design Requirements to be Identified and Substantiated.
1 2 3 4 5 6 7 8 9 10 11
20. 33.21 Engine cooling
21. 33.23 Engine mounting attachments and structure
22. 33.25 Accessory attachments
23. 33.27 Turbine, compressor, fan, and turbo-supercharger rotors
24. 33.28 Electrical and electronic control systems
25. 33.29 Instrument connection Repair Process Capability Technical Substantiation Requirements
Subpart E – Design and Construction; Turbine Aircraft Engines
26. 33.62 Stress analysis
27. 33.63 Vibration
28. 33.65 Surge and stall characteristics (Note 2)
29. 33.66 Bleed air system
30. 33.67 Fuel system
31. 33.68 Induction system icing (operability aspects) (Note 2)
32. 33.69 Ignitions system
33. 33.71 Lubrication system
34. 33.72 Hydraulic actuating systems
35. 33.73 Power or thrust response
36. 33.74 Continued rotation