AC 43.13-1B

U.S . Department of Transportation Federal Aviation Administration Advisory Circular Subject: Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair Date: 9/8/98 AC No: 43.13-1B Init iated by: AFS-300 Change: 1

1. PU RPOSE OF THIS ADVISORY CIRCULAR (AC).

a. This AC contains methods, techniques, and practices acceptable to the Federal Aviation Administration (FAA) for performing inspections and minor repairs of nonpressurized areas of civil aircraft unless the repair at issue is recommended against in the applicable manufacturer’s maintenance or repair instructions. The repair data described in this AC may be used as a basis for FAA-approved data for major repairs. The repair data may be used as FAA-approved data for repairs of nonpressurized areas of civil aircraft provided the AC chapter, page, and paragraph are listed in Block 8 of FAA Form 337, Major Repair and Alteration (Airframe, Powerplant, Propeller, or Appliance) and the data are:

(1) Appropriate to the product being repaired;

(2) Directly applicable to the repair being made; and

(3) Not contrary to manufacturer’s data.

b. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way, and the document is intended only to provide information to the public regarding existing requirements under the law or agency policies.

2. AUDIENCE. This AC is intended for use by persons performing maintenance, alteration, or preventive maintenance on aircraft, engines, propellers, or appliances in accordance with Title 14 of the Code of Federal Regulations (14 CFR) part 43.

3. WHERE YOU CAN FIND THIS AC. You can find this AC on the FAA’s website at https://www.faa.gov/regulations_policies/advisory_circulars and the Dynamic Regulatory System (DRS) at https://drs.faa.gov.

4. WHAT THIS AC CANCELS. AC 43.13-1A, Acceptable Methods, Techniques, and Practices—Aircraft Inspection and Repair, dated December 22, 1976, is canceled.

5. REFERENCE. Title 14 CFR part 43, § 43.13(a) states that each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or appliance shall use the methods, techniques, and practices prescribed in the current manufacturer’s maintenance manual or instructions for continued airworthiness (ICA) prepared by its manufacturer, or other methods, techniques, or practices acceptable to the Administrator, except

as noted in § 43.16. FAA inspectors are prepared to answer questions that may arise in this regard. Persons engaged in the inspection and repair of civil aircraft should be familiar with 14 CFR Part 43, Maintenance, Preventive Maintenance, Rebuilding, and Alteration, and Part 65, Certification: Airmen Other Than Flight Crewmembers, subparts A, D, and E, and the applicable airworthiness requirements under which the aircraft was type certificated.

6. ACKNOWLEDGMENTS. The FAA would like to thank the following persons and organization for their assistance in producing AC 43.13-1B: Richard Finch, Richard Fischer, Michael Grimes, Ray Stits, William A. Watkins, and the SAE, Aerospace Electronics and Electrical Systems Division. Acknowledgment is also extended to all in the aviation community who commented on the document.

7. AC FEEDBACK FORM. For your convenience, the AC Feedback Form is the last page of this AC. Note any deficiencies found, clarifications needed, or suggested improvements regarding the contents of this AC on the Feedback Form.

A cting Deputy Director, Flight Standards Service

CONTENTS Paragraph Page

CHAPTER 1. WOOD STRUCTURE1-1

SECTION 1. MATERIALS AND PRACTICES1-1

1-1. GENERAL1-1

1-2. WOODS1-1

1-3. MODIFIED WOOD PRODUCTS1-5

1-4. ADHESIVES1-5

1-5. BONDING PRECAUTIONS1-7

1-6. PREPARATION OF WOOD SURFACES FOR BONDING1-7

1-7. APPLYING THE ADHESIVE1-8

1-8. ASSEMBLY TIME IN BONDING1-8

1-9. BONDING TEMPERATURE1-9

1-10. CLAMPING PRESSURE1-9

1-11. METHOD OF APPLYING PRESSURE1-9

1-12.–1-17. [RESERVED.]1-10

SECTION 2. HEALTH AND SAFETY1-11

1-18. GENERAL1-11

1-19. SANDING IN AREAS OF EXISTING BOND JOINTS AND FINISHES1-11

1-20. HANDLING OF ADHESIVES AND FINISHES1-11

1-21.–1-26. [RESERVED.]1-11

SECTION 3. INSPECTION1-12

1-27. GENERAL1-12

1-28. TYPES OF DETERIORATION AND DAMAGE1-12

1-29. INSPECTION METHODS1-12

1-30.–1-35. [RESERVED.]1-15

SECTION 4. REPAIRS1-16

1-36. GENERAL1-16

1-37. REPLACEMENT OF DRAIN HOLES AND SKIN STIFFENERS1-16

1-38. CONTROL SURFACE FLUTTER PRECAUTIONS1-16

1-39. SCARF JOINTS1-16

1-40. SPLICING OF SPARS1-17

1-41. SPAR REPLACEMENT1-22

1-42. SPLICING OF BOX SPAR WEBS1-23

1-43. REPLACING SOLID-TYPE SPARS WITH LAMINATED-TYPE SPARS1-23

1-44. SPAR LONGITUDINAL CRACKS AND LOCAL DAMAGE1-23

1-45. ELONGATED HOLES IN SPARS1-25

1-46. RIB REPAIRS1-25

1-47. PLYWOOD SKIN REPAIR1-28

1-48. DETERMINATION OF SINGLE OR DOUBLE CURVATURE1-29

1-49. REPAIRS TO SINGLE CURVATURE PLYWOOD SKIN1-29

1-50. REPAIRS TO DOUBLE CURVATURE PLYWOOD SKIN1-30

1-51. TYPES OF PATCHES1-30

1-52. FABRIC PATCH1-38

1-53.–1-63. [RESERVED.]1-38

SECTION 5. FINISHING WOOD STRUCTURES1-39

1-64. GENERAL1-39

1-65. ACCEPTABLE FINISHES1-39

1-66. PRECAUTIONS1-39

1-67. FINISHING OF INTERIOR SURFACES1-40

1-68. FINISHING OF EXTERIOR SURFACES1-40

1-69. FINISHING OF END GRAIN SURFACES1-40

1-70. FINISHING WITH FABRIC OR TAPE1-41

1-71. SEALING OF BOLT HOLES1-41

1-72.–1-79. [RESERVED.]1-41

CHAPTER 2. FABRIC COVERING2-1

SECTION 1. PRACTICES AND PRECAUTIONS2-1

2-1. GENERAL2-1

2-2. PROBLEM AREAS2-1

2-3. AIRCRAFT FABRIC-SYNTHETIC2-1

2-4. AIRCRAFT FABRIC-NATURAL2-2

2-5. RECOVERING AIRCRAFT2-3

2-6. PREPARATION OF THE STRUCTURE FOR COVERING2-4

2-7. FABRIC SEAMS2-6

2-8. COVERING METHODS2-10

2-9. REINFORCING TAPE2-11

2-10. LACING2-12

2-11. STITCH SPACING2-22

2-12. FASTENERS2-23

2-13. F INISHING TAPE2-24

2-14. INSPECTION RINGS AND DRAIN GROMMETS2-25

2-15.–2-19. [RESERVED.]2-26

SECTION 2. APPLICATION OF DOPE2-27

2-20. GENERAL2-27

2-21. DOPE APPLICATION PROCEDURE (Natural Fabrics)2-29

2-22. COVERING OVER PLYWOOD2-31

2-23. COATING APPLICATION DEFECTS2-32

2-24.–2-29. [RESERVED.]2-33

SECTION 3. INSPECTION AND TESTING2-34

2-30. GENERAL2-34

2-31. FABRIC IDENTIFICATION2-35

2-32. COATING IDENTIFICATION2-36

2-33. STRENGTH CRITERIA FOR AIRCRAFT FABRIC2-36

2-34. FABRIC TESTING2-36

2-35. REJUVENATION OF THE DOPE FILM2-37

2-36.–2-41. [RESERVED.]2-37

SECTION 4. REPAIRS TO FABRIC COVERING2-38

2-42. GENERAL2-38

2-43. REPAIR OF TEARS AND ACCESS OPENINGS2-38

2-44. SEWN-PATCH REPAIR2-40

2-45. DOPED-ON PATCH REPAIR2-41

2-46.–2-51. [RESERVED.]2-42

CHAPTER 3. FIBERGLASS AND PLASTICS3-1

SECTION 1. REPAIR OF LIGHT LOAD LAMINATE STRUCTURES3-1

3-1. GENERAL3-1

3-2. FIBERGLASS LAMINATE REPAIRS3-1

3-3. REPAIRING HOLES3-4

3-4. SAMPLE BAGGING AND CURING PROCESS3-10

3-5.–3-9. [RESERVED.]3-12

SECTION 2. METALLIC SANDWICH SECONDARY STRUCTURE REPAIRS3-13

3-10. REPAIRS TO METALLIC SANDWICH SECONDARY STRUCTURE3-13

3-11. FINISHING3-19

3-12.–3-17. [RESERVED.]3-19

SECTION 3. TRANSPARENT PLASTICS3-20

3-18. GENERAL3-20

3-19. STORAGE AND HANDLING3-20

3-20. FORMING PROCEDURES AND TECHNIQUES3-20

3-21. HEATING3-21

3-22. FORMS3-22

3-23. FORMING METHODS3-22

3-24. REPAIR OF PLASTICS3-26

3-25. CLEANING AND POLISHING TRANSPARENT PLASTIC3-29

3-26. REPLACEMENT PANELS3-29

3-27. INSTALLATION PROCEDURES3-29

3-28.–3-39. [RESERVED.]3-30

SECTION 4. WINDSHIELDS, ENCLOSURES, AND WINDOWS3-31

3-40. GENERAL3-31

3-41. PROTECTION3-32

3-42. WINDSHIELD INSTALLATION3-32

3-43.–3-47. [RESERVED.]3-33

CHAPTER 4. METAL STRUCTURE, WELDING, AND BRAZING4-1

SECTION 1. IDENTIFICATION OF METALS4-1

4-1. GENERAL4-1

4-2. IDENTIFICATION OF STEEL STOCK4-1

4-3. INTERCHANGEABILITY OF STEEL TUBING4-3

4-4. IDENTIFICATION OF ALUMINUM4-3

4-5.–4-15. [RESERVED.]4-5

SECTION 2. TESTING OF METALS4-6

4-16. HARDNESS TESTING4-6

4-17. ROCKWELL HARDNESS TEST4-6

4-18. BRINELL HARDNESS TEST4-7

4-19. VICKERS HARDNESS TEST4-8

4-20. MICROHARDNESS TESTING4-9

4-21. INDENTATIONS4-10

4-22. MAGNETIC TESTING4-10

4-23. ALUMINUM TESTING4-10

4-24.–4-35. [RESERVED.]4-11

SECTION 3. PRECAUTIONARY MEASURES4-12

4-36. FLUTTER AND VIBRATION PRECAUTIONS4-12

4-37. LOAD FACTORS FOR REPAIRS4-13

4-38. TRANSFER OF STRESSES WITHIN A STRUCTURE4-13

4-39.–4-49. [RESERVED.]4-13

SECTION 4. METAL REPAIR PROCEDURES4-14

4-50. GENERAL4-14

4-51. RIVETED (OR BOLTED) STEEL TRUSS-TYPE STRUCTURES4-14

4-52. ALUMINUM ALLOY STRUCTURES4-14

4-53. SELECTION OF ALUMINUM FOR REPLACEMENT PARTS4-15

4-54. HEAT TREATMENT OF ALUMINUM ALLOY PARTS4-16

4-55. BENDING METAL4-16

4-56. SETBACK4-16

4-57. RIVETING4-19

4-58. REPAIR METHODS AND PRECAUTIONS FOR

ALUMINUM STRUCTURE4-33

4-59. REPAIRING CRACKED MEMBERS4-49

4-60. STEEL AND ALUMINUM FITTINGS4-55

4-61. CASTINGS4-56

4-62. SELECTIVE PLATING IN AIRCRAFT MAINTENANCE4-57

4-63.–4-73. [RESERVED.]4-62

SECTION 5. WELDING AND BRAZING4-63

4-74. GENERAL4-63

4-75. EQUIPMENT SELECTION4-64

4-76. ACCURATELY IDENTIFY THE TYPE OF

MATERIAL TO BE REPAIRED4-64

4-77. PREPARATION FOR WELDING4-65

4-78. INSPECTION OF A COMPLETED WELD4-65

4-79. MICROFISSURES4-65

4-80. NONDESTRUCTIVE TESTING4-66

4-81. PRACTICES TO GUARD AGAINST4-66

4-82. TORCH SIZE (Oxyacetylene welding)4-66

4-83. WELDING RODS AND ELECTRODES4-66

4-84. ROSETTE WELDS4-67

4-85. HEAT-TREATED MEMBERS4-67

4-86. TYPES OF WELDING4-68

4-87. ELECTRIC-RESISTANCE WELDING4-70

4-88. BRAZING4-71

4-89. AIRCRAFT PARTS NOT TO BE WELDED4-75

4-90. WELDING ROD SELECTION4-75

4-91. REPAIR OF TUBULAR MEMBERS4-76

4-92. REPAIR BY WELDED SLEEVE4-77

4-93. REPAIR BY BOLTED SLEEVE4-79

4-94. WELDED-PATCH REPAIR4-79

4-95. SPLICING TUBING BY INNER-SLEEVE METHOD4-79

4-96. SPLICING TUBING BY OUTER-SLEEVE METHOD4-80

4-97. SPLICING USING LARGER DIAMETER REPLACEMENT TUBES4-83

4-98. REPAIRS AT BUILT-IN FUSELAGE FITTINGS4-84

4-99. ENGINE-MOUNT REPAIRS4-86

4-100. BUILT-UP TUBULAR WING OR TAIL-SPARS4-86

4-101. WING-BRACE STRUTS AND TAIL-BRACE STRUTS4-90

4-102. LANDING GEAR REPAIR4-91

4-103. REPAIRS TO WELDED ASSEMBLIES4-92

4-104. STAINLESS STEEL STRUCTURE4-93

4-105.–4-110. [RESERVED.]4-93

SECTION 6. WELDING AND BRAZING SAFETY4-94

4-111. GENERAL4-94

4-112. FIRE AND EXPLOSION SAFETY4-94

4-113. WELDING WORK AREA4-94

4-114. FIRE PROTECTION4-95

4-115. PROTECTIVE APPAREL4-95

4-116. FIRST-AID KITS4-96

4-117.–4-128. [RESERVED.]4-96

CHAPTER 5. NONDESTRUCTIVE INSPECTION (NDI)5-1

SECTION 1. GENERAL5-1

5-1. GENERAL5-1

5-2. APPROVED PROCEDURES5-1

5-3. NDT LEVELS5-1

5-4. TRAINING, QUALIFICATION, AND CERTIFICATION5-2

5-5. FLAWS5-2

5-6. SELECTING THE NDI METHOD5-6

5-7. TYPES OF INSPECTIONS5-8

5-8.–5-14. [RESERVED.]5-8

SECTION 2. VISUAL INSPECTION5-9

5-15. GENERAL5-9

5-16. SIMPLE VISUAL INSPECTION AIDS5-9

5-17. BORESCOPES5-10

5-18. VISUAL INSPECTION PROCEDURES5-11

5-19.–5-24. [RESERVED.]5-13

SECTION 3. EDDY CURRENT INSPECTION5-14

5-25. EDDY CURRENT INSPECTION5-14

5-26. EDDY CURRENT COILS AND PROBES5-15

5-27. FIELD APPLICATION OF EDDY CURRENT INSPECTION5-16

5-28. SURFACE INSPECTION5-16

5-29. SUBSURFACE INSPECTION5-17

5-30. CORROSION INSPECTION5-18

5-31. ESTABLISHING EDDY CURRENT INSPECTION PROCEDURES5-18

5-32.–5-39. [RESERVED.]5-19

SECTION 4. MAGNETIC PARTICLE INSPECTION5-20

5-40. GENERAL5-20

5-41. PRINCIPLES OF OPERATION5-20

5-42. APPLICATIONS5-21

5-43. ELECTRICAL MAGNETIZING EQUIPMENT5-21

5-44. MATERIALS USED IN MAGNETIC PARTICLE INSPECTION5-22

5-45. PREPARATION OF SURFACE5-24

5-46. METHODS OF EXAMINATION5-25

5-47. APPLICATION OF MAGNETIC PARTICLES5-25

5-48. MAGNETIZATION5-25

5-49. DETERMINATION OF FIELD STRENGTH5-28

5-50. SPECIAL EXAMINATION TECHNIQUES5-28

5-51. DEMAGNETIZATION AND POST-EXAMINATION CLEANING5-30

5-52.–5-59. [RESERVED.]5-31

SECTION 5. PENETRANT INSPECTION5-32

5-60. GENERAL5-32

5-61. EQUIPMENT USED IN THE PENETRANT INSPECTION PROCESS5-33

5-62. BASIC STEPS TO PERFORM PENETRATION INSPECTION5-34

5-63. CLEANERS AND APPLICATIONS5-37

5-64. TECHNICAL STANDARDS5-38

5-65.–5-72. [RESERVED.]5-39

SECTION 6. RADIOGRAPHY (X-RAY) INSPECTION5-40

5-73. GENERAL5-40

5-74. LIMITATIONS5-40

5-75. FILM OR PAPER RADIOGRAPHY5-40

5-76. REAL-TIME RADIOGRAPHY5-41

5-77. ADVANTAGE OF REAL-TIME RADIOGRAPHY OVER

FILM RADIOGRAPHY5-41

5-78. COMPUTED TOMOGRAPHY (CT)5-41

5-79. USES OF RADIOGRAPHY5-41

5-80. COMPARISON WITH OTHER NDI METHODS5-41

5-81. FLAWS5-42

5-82. FIELD INSPECTION5-42

5-83. SAFETY5-42

5-84.–5-88. [RESERVED.]5-42

SECTION 7. ULTRASONIC INSPECTION5-43

5-89. GENERAL5-43

5-90. SOUND REFLECTION5-43

5-91. ULTRASONIC INSPECTION TECHNIQUES5-44

5-92. FLAW DETECTION5-44

5-93. BASIC EQUIPMENT5-45

5-94. INSPECTION OF BONDED STRUCTURES5-47

5-95. BOND TESTING INSTRUMENTS5-52

5-96. THICKNESS MEASUREMENTS5-53

5-97. LEAK TESTING5-54

5-98.–5-104. [RESERVED.]5-54

SECTION 8. TAP TESTING5-55

5-105. GENERAL5-55

5-106.–5-111. [RESERVED.]5-55

SECTION 9. ACOUSTIC-EMISSION5-56

5-112. GENERAL5-56

5-113. APPLICATIONS5-56

5-114.–5-119. [RESERVED.]5-56

SECTION 10. THERMOGRAPHY5-57

5-120. GENERAL5-57

5-121.–5-126. [RESERVED.]5-57

SECTION 11. HOLOGRAPHY5-58

5-127. GENERAL5-58

5-128.–5-133. [RESERVED.]5-58

SECTION 12. SHEAROGRAPHY5-59

5-134. GENERAL5-59

5-135.–5-140. [RESERVED.]5-59

CHAPTER 6. CORROSION, INSPECTION, AND PROTECTION6-1

SECTION 1. GENERAL6-1

6-1. GENERAL6-1

6-2. FACTORS INFLUENCING CORROSION6-2

6-3. COMMON CORROSIVE AGENTS6-3

6-4. MICRO-ORGANISMS6-4

6-5.–6-10. [RESERVED.]6-4

SECTION 2. TYPES OF CORROSION6-5

6-11. GENERAL6-5

6-12. GENERAL SURFACE CORROSION6-5

6-13. PITTING CORROSION6-5

6-14. CONCENTRATION CELL CORROSION6-6

6-15. ACTIVE-PASSIVE CELLS6-7

6-16. FILIFORM CORROSION6-8

6-17. INTERGRANULAR CORROSION6-8

6-18. EXFOLIATION CORROSION6-9

6-19. GALVANIC CORROSION6-10

6-20. STRESS CORROSION CRACKING6-10

6-21. FATIGUE CORROSION6-12

6-22. FRETTING CORROSION6-12

6-23.–6-28. [RESERVED.]6-13

SECTION 3. CORROSION PROTECTION MEASURES FOR BASIC MATERIALS6-14

6-29. GENERAL6-14

6-30. ANODIZING AND RELATED PROCESSES6-14

6-31. PLATING6-14

6-32. PHOSPHATE RUST-PROOFING6-14

6-33. CHROME-PICKLE TREATMENT6-14

6-34. DICHROMATE TREATMENT6-14

6-35. STANNATE IMMERSION TREATMENT6-15

6-36. GALVANIC ANODIZING TREATMENT6-15

6-37. CLADDING6-15

6-38. METAL SPRAYING6-15

6-39. SHOT-PEENING6-15

6-40. ORGANIC COATINGS6-15

6-41. DOPE PROOFING6-15

6-42. TUBE INTERIORS6-15

6-43.–6-49. [RESERVED.]6-15

SECTION 4. CORROSION PREVENTIVE MAINTENANCE6-16

6-50. GUIDELINES: ALL AIRCRAFT6-16

6-51. GUIDELINES: AIRCRAFT OPERATING OVER SALTWATER6-16

6-52.–6-62. [RESERVED.]6-17

SECTION 5. VISUAL CORROSION INSPECTION GUIDE FOR AIRCRAFT6-18

6-63. GENERAL6-18

6-64. EXHAUST TRAIL AREAS6-18

6-65. BATTERY COMPARTMENTS AND BATTERY VENT OPENINGS6-18

6-66. LAVATORIES AND GALLEYS6-18

6-67. BILGE AREAS6-18

6-68. WHEEL WELLS AND LANDING GEAR6-18

6-69. EXTERNAL SKIN AREAS6-18

6-70. WATER ENTRAPMENT AREAS6-19

6-71. ENGINE FRONTAL AREAS6-19

6-72. ELECTRONIC PACKAGE COMPARTMENTS6-19

6-73. FLEXIBLE HOSE ASSEMBLIES6-19

6-74. SANDWICH PANELS6-19

6-75. CONTROL CABLES6-19

6-76. INTEGRAL FUEL CELLS6-20

6-77. ELECTRICAL CONNECTORS6-20

6-78.–6-88. [RESERVED.]6-20

SECTION 6. CORROSION REMOVAL PROCEDURES6-21

6-89. GENERAL6-21

6-90. SAFETY PRECAUTIONS6-21

6-91. CORROSION CONTROL WORK PROCEDURES6-22

6-92.–6-112. [RESERVED.]6-23

SECTION 7. BASIC CORROSION REMOVAL TECHNIQUES6-24

6-113. GENERAL6-24

6-114. PREPARATIONS FOR REWORK6-24

6-115. FAIRING OR BLENDING REWORKED AREAS6-24

6-116. CORROSION REMOVAL BY BLASTING6-28

6-117. CLEANERS, POLISHES, AND BRIGHTENERS6-28

6-118. STANDARD METHODS6-29

6-119.–6-131. [RESERVED.]6-29

SECTION 8. ALUMINUM AND ALUMINUM ALLOYS6-30

6-132. GENERAL6-30

6-133. SPECIAL TREATMENT OF ANODIZED SURFACES6-30

6-134. REPAIR OF ALUMINUM ALLOY SHEET METAL6-30

6-135. CORROSION REMOVAL AROUND COUNTERSUNK FASTENERS IN

ALUMINUM ALLOY6-31

6-136. EXAMPLES OF REMOVING CORROSION FROM ALUMINUM AND

ALUMINUM ALLOYS6-31

6-137.–6-147. [RESERVED.]6-34

SECTION 9. MAGNESIUM AND MAGNESIUM ALLOYS6-35

6-148. GENERAL6-35

6-149. TREATMENT OF WROUGHT MAGNESIUM SHEETS AND FORGINGS6-35

6-150. REPAIR OF MAGNESIUM SHEET METAL AFTER EXTENSIVE

CORROSION REMOVAL6-35

6-151. IN-PLACE TREATMENT OF MAGNESIUM CASTINGS6-36

6-152. EXAMPLE OF REMOVING CORROSION FROM MAGNESIUM6-36

6-153.–6-163. [RESERVED.]6-40

SECTION 10. FERROUS METALS6-41

6-164. GENERAL6-41

6-165. SPECIAL TREATMENT OF HIGH-STRENGTH STEEL6-41

6-166. SPECIAL TREATMENT OF STAINLESS STEEL6-41

6-167. EXAMPLE OF REMOVING CORROSION FROM FERROUS METALS6-42

6-168.–6-178. [RESERVED.]6-42

SECTION 11. OTHER METALS AND ALLOYS6-43

6-179. NOBLE METAL COATINGS CLEANUP AND RESTORATION6-43

6-180. COPPER AND COPPER ALLOYS6-43

6-181. TITANIUM AND TITANIUM ALLOYS6-43

6-182.–6-192. [RESERVED.]6-44