structural repair manual duct reinforcement repair … · 2008. 1. 22. · structural repair manual...

DUCT REINFORCEMENT REPAIR — REPAIRS

NOTICE: THIS REPAIR PAGEBLOCK (PAGES 201-2XX) IS FAA APPROVED AND IS INTENDED FOROPERATOR USE IN ACHIEVING REPAIR INSTALLATIONS ACCEPTABLE TO THEIR LOCALAPPROVAL AUTHORITY.

SPECIFIC REPAIR INSTALLATION CLASSIFICATION (MAJOR OR MINOR) AND SPECIFICREQUIREMENTS FOR DATA FROM THIS PAGEBLOCK (PAGES 201-2XX) WILL BEDICTATED BY THE NATURE OF THE STRUCTURE BEING REPAIRED.

IT IS THE RESPONSIBILITY OF THE OPERATOR TO ENSURE THAT THE REPAIRINSTALLATION, DOCUMENTATION AND ANY REQUIRED ENGINEERING ACTION(EVALUATION, DESIGN, ANALYSIS, ETC.) MEET THE REGULATIONS OF THE FAA OROTHER GOVERNING REGULATORY AGENCY, AS APPLICABLE, BEFORE RETURNINGTHE AIRCRAFT TO SERVICE.

1. Duct Reinforcement Repair

A. Procedure

(1) Abraded, corroded, dented, punctured and cracked areas of the ducts which cannot bereworked within defined limits of procedures Corrosion Rework, 51-77-10, Repair, Scratch andAbrasion Rework, 51-77-11, Repair, Dent and Puncture Rework, 51-77-12, Repair and DuctCrack Repair, 51-77-14, Repair are to be repaired to the requirements of this procedure.

(2) See Tube Repair - Chapter 21 Air Conditioning Ducts (within Pressure Vessel), 51-77-01,General, Tube Repair - Chapter 21 Equipment Cooling Ducts, 51-77-01, General, Tube Repair- Chapter 21 Air Conditioning Ducts (External to Pressure Vessel), 51-77-01, General, TubeRepair - Chapter 28 Fuel Lines, 51-77-01, General, Tube Repair - Chapter 30 Ice and Rain,51-77-01, General, Tube Repair - Chapter 36 Pneumatic Ducts, 51-77-01, General, TubeRepair - ATA Chapter 71: Powerplant Ducts, 51-77-01, General, Tube Repair - ATA Chapter 75:Air Ducts, 51-77-01, General or Tube Repair - ATA Chapter 80: Starting Ducts, 51-77-01,General for rework limitations to individual ducts. See Figures 201 thru 204 for repair limitationsto listed ducts.

(3) Reinforcement straps / doublers are to be fabricated from listed repair material. See Table 201and Figures 205, 206, 207 and 208 for general strap / doubler requirements.

(a) Strap / doubler thickness must be one gage (approximately 0.005 inch) thicker than theduct wall being repaired.

(b) Ducts listed in Tube Repair - Chapter 21 Air Conditioning Ducts (within Pressure Vessel),51-77-01, General, Tube Repair - Chapter 21 Equipment Cooling Ducts, 51-77-01,General, Tube Repair - ATA Chapter 71: Powerplant Ducts, 51-77-01, General and TubeRepair - ATA Chapter 75: Air Ducts, 51-77-01, General shall use a maximum of a 0.040thick repair strap / doubler.

(c) The reinforcement strap / doubler should be fabricated, where possible, from one piece ofmaterial.

(d) Straps may be fabricated from a tube or duct sections cut lengthwise with a single cut.

(e) If welded tubing sections are used the cut shall be made at the pre-existing weld line.

(f) Form reinforcement strap / doublers to conform to the duct shape prior to welding.

STRUCTURAL REPAIR MANUAL

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1 The accuracy of the forming must be sufficient so that the fit up requirements aremet. See Figure 209.

(g) Reinforcement strap / doublers can be circular or rectangular in form.

NOTE: Rectangular straps not extending completely around the duct must have a cornerradii of at least 0.500 inch.

(h) Clean reinforcement strap / doublers per Duct Cleaning and Passivation, 51-77-01,Allowable Damage.

(4) Maintain a minimum of 0.500 inch distance between weld repairs.

(5) Tack weld, clamp and / or holding fixtures are to be used to position the reinforcement strap /doublers in position.

(a) The fit-up requirements of Figure 209 are to be maintained.

(6) Repair damaged or corroded areas adjacent to attachments per the following requirements orrestrictions:

(a) Butt weld the edge of the strap / doubler to the edge of a flange or doublers if damagedarea is near a flange or weld-attached doublers.

(b) Butt weld to edge of flange or doublers if this results in a reduction in the number of weldsrequired.

(7) The duct area being repaired must be free of wrinkles.

(a) Dent depths are limited to 10% of the duct outer diameter with a length and width not toexceed 25% of the duct outer diameter.

(b) Any gap beyond those specified will prevent proper fitting of repair parts.

(8) Install individual reinforcement strap / doublers if damage areas are located more than 4.00inches apart lengthwise.

(9) Reinforcement repair strap / doubler coverage shall not exceed:

(a) Total duct length of 75% for the following listed ducts:

• Tube Repair - Chapter 21 Air Conditioning Ducts (within Pressure Vessel), 51-77-01,General

• Tube Repair - Chapter 21 Equipment Cooling Ducts, 51-77-01, General• Tube Repair - Chapter 30 Ice and Rain, 51-77-01, General• Tube Repair - Chapter 36 Pneumatic Ducts, 51-77-01, General• Tube Repair - ATA Chapter 71: Powerplant Ducts, 51-77-01, General

(b) Total duct length of 50% for the following listed ducts:

• Tube Repair - Chapter 21 Air Conditioning Ducts (External to Pressure Vessel),51-77-01, General

• Tube Repair - Chapter 28 Fuel Lines, 51-77-01, General• Tube Repair - ATA Chapter 75: Air Ducts, 51-77-01, General• Tube Repair - ATA Chapter 80: Starting Ducts, 51-77-01, General

NOTE: Contact Gulfstream Technical Operations if strap / doubler coverage exceedsthese stated limits.


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(10) Reinforcement strap / doublers must conform to the appropriate authorized repair details. SeeTube Repair - Chapter 21 Air Conditioning Ducts (within Pressure Vessel), 51-77-01, General,Tube Repair - Chapter 21 Equipment Cooling Ducts, 51-77-01, General, Tube Repair - Chapter21 Air Conditioning Ducts (External to Pressure Vessel), 51-77-01, General, Tube Repair -Chapter 28 Fuel Lines, 51-77-01, General, Tube Repair - Chapter 30 Ice and Rain, 51-77-01,General, Tube Repair - Chapter 36 Pneumatic Ducts, 51-77-01, General, Tube Repair - ATAChapter 71: Powerplant Ducts, 51-77-01, General, Tube Repair - ATA Chapter 75: Air Ducts,51-77-01, General or Tube Repair - ATA Chapter 80: Starting Ducts, 51-77-01, General forrepair details authorized for each duct.

(11) Install reinforcement strap / doublers as follows:

(a) Maintain 0.50 inch minimum distance from circumferential welds at end flanges, bellows,ball joints, swivel and / or expansion joints and individual duct section butt welds. SeeFigures 201 thru 204 for repair limitations to specific ducts.

(b) Vary strap / doubler lengths to provide fit-up suitable for fillet or butt welding strap / doublerends to other doubler fillet welds or duct longitudinal welds. See Figure 209 for fit uprequirements.

(c) Weld runs immediately adjacent to existing duct circumferential welds must be avoided ifat all possible, but if it becomes necessary the strap / doublers must be extended acrossthe existing weld in order to have the edge weld of the strap located in previouslyunwelded material. The existing weld may be machined flush with the duct O.D. under thestrap / doubler. See Figure 209 for fit up requirements.

WARNING: WELDING OPERATIONS PRODUCE HEAT, HIGHLY TOXIC FUMES,INJURIOUS RADIATION, METAL SLAG AND AIRBORNE PARTICLES.WELDING GOGGLES WITH PROPER TINTED LENSES, JACKET OR APRONAND WELDERS BOOTS ARE MANDATORY.

(12) Weld per Fusion Welding Procedure, 51-77-03, Repair.

(13) Hydrostatic pressure proof test. See Hydrostatic Pressure Test, 51-77-04, Repair.

(14) See Finish Requirements, 51-77-05, Repair for finish requirements.

(15) See Insulation, 51-77-06, Repair for insulation requirements.


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Table 201: Duct Repair Material

DUCTALLOY

REPAIRALLOY

COMMERCIALSPECIFICATION

GOVERNMENTSPECIFICATION

INDUSTRYSPECIFICATION

SAE ASTM

SHEET TUBEBARRODMISC




5052-05052-0H

5052-05052-0H

5052-0H 5052-0H 5052-0HQQ-A-250/

8WW-T-700/

4AMS4015

AMS4069AMS4070AMS4071

ASTMB209

ASTM B210

ASTM B221

ASTM B234

ASTM B313

ASTM B211

ASTM B221

6061-0 6061-0 6061-0 6061-0QQ-A-250/

11WW-T-700/

6QQ-A-200/

8AMS 4025AMS 4027

AMS 4079AMS 4080

AMS4017

6061-T6 6061-T6 6061-T6 6061-T6 6061-T6QQ-A-250/

11WW-T-700/

6QQ-A-200/

8AMS 4027

AMS 4080AMS 4082AMS 4083

AMS 4017ASTM B

209

ASTM B210

ASTM B221

ASTM B234

ASTM B313

ASTM B211

ASTM B221

CRES321A

CRES321A

CRES321A

CRES321A

CRES321A

QQ-S-776 MIL-T-8808 QQ-S-763 AMS5510

AMS5557AMS5559AMS5570AMS5576

AMS5645

ASTM A167

ASTM A240

ASTM A276

ASTM A479

ASTM A276

ASTM A479

Inconel625

Inconel625

Inconel625

Inconel625

Inconel625

AMS5599 AMS5666 AMS5666ASTM B

443ASTM B

444ASTM B

446


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Ducting - 12th Stage BleedFigure 201


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Ducting - Precooler InletFigure 202



Ducting - 7th StageFigure 203


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Ducting - 7th and 12th Stage BleedFigure 204



Duct Straight Section Reinforcement Patch Repair - GeneralFigure 205


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Duct Curved Section Reinforcement Patch Repair - GeneralFigure 206



Duct Straight Section Reinforcement Repair - GeneralFigure 207


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Duct Sonic Section Reinforcement Repair - GeneralFigure 208 (Sheet 1 of 2)



Duct Sonic Section Reinforcement Repair - GeneralFigure 208 (Sheet 2 of 2)


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Duct Reinforcement Welding RequirementsFigure 209



2. Duct Reinforcement Welding Requirements

A. Procedure

NOTE: The following procedure is performed in conjunction with Figure 209.

(1) Joint fit-up for welding is as shown in Details I, II and III for 90% of the weld length.

(a) The length of areas of deviation are not to exceed 3% of weld length.

(b) Such areas of deviation must be separated by a distance equal to 6% of the weld length.

(c) Maximum joint fit-up values are not to be exceeded by more than 100% in these areas ofdeviation.

(2) Joint spacing for welding reinforcement or repair strap ends on machine welded and sized ductlengths. See Detail II.

(3) Recommended joint spacing for welding reinforcement or repair straps on half shell ductlengths. See Detail II.

(a) Where spacing recommended, wider gaps may be used.

(b) Strap fit-up of Detail I and weld quality requirements of Fusion Welding Procedure,51-77-03, Repair and MIL-STD-2219 must be maintained regardless of joint spacing used.

(4) Joint local reinforcements to duct wall and gussets, stiffeners or brackets using one weld passwhere no prior weld exists. See Detail III.

(a) Welding the gusset, stiffener or bracket to the duct wall prior to attaching the localreinforcement is optional.

(b) Regardless of the procedure used, the finished welds must meet all applicablerequirements of Fusion Welding Procedure, 51-77-03, Repair and MIL-STD-2219.

(5) Mismatch not to exceed 10% T. See Detail IV.

3. Duct Straight Section Reinforcement Patch Repair — General

A. General

Duct assemblies may have been fabricated from half shells or may be machine welded ducts. Halfshell ducts are quite obvious. The two lengthwise weld beads are thicker than the duct wall. The beadmay be difficult to discern on ducts which have been in service.

B. Procedure


(1) On machine or half shell welded ducts the location of the welds relative to the existinglengthwise machine weld is optional within the following requirements: Lengthwise welds are tobe located on top of existing lengthwise welds or must be located 0.500 minimum away inunaffected parent material.

WARNING: WARNING: WELDING OPERATIONS PRODUCE HEAT, HIGHLY TOXICFUMES, INJURIOUS RADIATION, METAL SLAG AND AIRBORNEPARTICLES. WELDING GOGGLES WITH PROPER TINTED LENSES,JACKET OR APRON AND WELDERS BOOTS ARE MANDATORY.

(a) Weld toward pressure relief holes, then plug weld holes.

(2) See Duct Reinforcement Repair, 51-77-13, Repair for strap thickness.

(3) This dimension is to be a minimum of 1.00 to a maximum of 50% of the total duct length. Use


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the minimum width strap which can be used to accomplish the repair within these limits.


WARNING: DRILLING AND GRINDING OPERATIONS CREATE METAL PARTICLESWHICH MAY ENTER THE EYE. WEARING OF GOGGLES IS REQUIRED.

(5) Prior to installation, drill pressure relief holes in repair patches as follows:

(a) Use drill size No. 30.

(b) Locate two relief holes in each strap half at diagonally opposed ends.

(c) Maintain 0.125 inch minimum distance between relief holes and any existing orsubsequent weld locations.

(d) Deburr all pressure relief holes prior to strap installation.

4. Duct Curved Section Reinforcement Patch Repair — General

A. General


B. Procedure


(1) The straps are to be butt welded together and then to the duct after the circumferential weldsare completed. On machine or half shell welded ducts, the location of the butt welds relative tothe existing lengthwise machine weld is optional within the following requirements:


(a) Lengthwise welds are to be located on top of existing lengthwise welds or must be located0.500 minimum away in unaffected parent material.

(b) The butt welds are to extend to and be fused with the circumferential welds.

(c) Weld toward pressure relief holes, then plug weld holes.


(3) This dimension is to be a minimum of 1 inch to a maximum of 6 inches. Use the minimum widthstrap which can be used to accomplish the repair within these limits.


(4) Drill pressure relief holes in strap or strap half at diagonally opposed ends.


(b) Locate two relief holes in each strap or strap half and between any two circumferentialwelds spaced 0.75 inch or more apart.





(5) The ability to repair corrosion or damage in elbows and bends is generally restricted. Thedifficulty is in forming the corrosion repair or reinforcement strap. In cases where repair isrequired, the following limitations apply:

(a) The same fit-up requirements are required as those for repairing straight sections. SeeDuct Reinforcement Welding Requirements, 51-77-13, Repair.

(b) Corrosion or reinforcement repairs may be made on both ends of a bend. This isapplicable for repairs which overlap the tangent point of the bend extending both straightand curved sections.

(c) Only one repair per curved section is permitted. This applies where repairs are fully withinthe bend.


5. Duct Straight Section Reinforcement Repair — General

A. General


B. Procedure


(1) The straps are to be butt welded together and then to the duct after the circumferential weldsare completed. See Section A - A.


(a) On machine or half shell welded ducts, the location of the butt welds relative to theexisting lengthwise machine weld is optional within the following requirements:

1 Lengthwise welds are to be located on top of existing lengthwise welds or must belocated 0.500 minimum away in unaffected parent material.

2 The butt welds are to extend to and be fused with the circumferential welds.

3 Weld toward pressure relief holes, then plug weld holes.


(3) This dimension is to be a minimum of 1 inch to a maximum of 50% of total duct length. Use theminimum width strap which can be used to accomplish the repair within these limits.


(4) Prior to doubler installation, drill pressure relief holes in strap or strap half at diagonally opposedends.


(b) Locate two relief holes in each strap or strap half and between any two circumferentialwelds spaced 0.75 inch or more apart.


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(5) Install strap halves on welded half shell ducts.

(a) The lengthwise weld beads are thicker than duct wall and are obvious on welded half shellducts.

(6) Butt weld the two half straps together on welded half shell ducts. See Section A - A.

(a) Then weld these to the existing lengthwise fusion welds after the circumferential welds arecompleted.

(b) The butt welds are to extend to and be fused with the circumferential weld.

(c) Weld toward relief holes, then plug holes.


6. Duct Conic Section Reinforcement Repair — General

A. General


B. Procedure


(1) The straps are to be butt welded together and then to the duct after the circumferential weldsare completed. On machine or half shell welded ducts, the location of the butt welds relative tothe existing lengthwise machine weld is optional within the following requirements:


(a) Lengthwise welds are to be located on top of existing lengthwise welds or must be located0.500 minimum away in unaffected parent material.

(b) The butt welds are to extend to and be fused with the circumferential welds.

(c) Weld toward pressure relief holes, then plug weld holes.

(2) See Duct Reinforcement Repair, 51-77-13, Repair strap thickness.

(3) This dimension is to be a minimum of 1 inch to a maximum of of 6 inches. Use the minimumwidth strap which can be used to accomplish the repair within these limits.


(4) Prior to doubler installation, drill pressure relief holes in strap or strap half at diagonally opposedends.


(b) Locate two relief holes in each strap or strap half and between any 2 circumferential weldsspaced 0.75 inch or more apart.





(5) The ability to repair corrosion or damage in tapered sections is generally restricted. Thedifficulty is in forming the corrosion repair or reinforcement strap. In cases where repair isrequired, the following limitations apply:

(a) The same fit-up requirements are required as those for repairing straight sections. SeeDuct Reinforcement Welding Requirements, 51-77-13, Repair.



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structural repair manual duct reinforcement repair … · 2008. 1. 22. · structural repair manual...

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