J.9 6930_25a_mthb_chg4.pdf

CHANGE U.S. DEPARTMENT OF TRANSPORTATION

FEDERAL AVIATION ADMINISTRATION

6930.25A

CHG 4

2/26/2002

SUBJ: MAINTENANCE OF STRUCTURES AND BUILDINGS

Distribution: Selected Airway Facilities Field and Regional Offices, ZAF-607, ZAF-657

Initiated By: AOS-220

1. PURPOSE. This change transmits revised maintenance interval pages to the structures and buildings. This directive implements Configuration Control Decision (CCD) No. N23834, Administrative Updates to Maintenance of Structures and Buildings.

2. DISTRIBUTION.

a. This directive is distributed to selected offices and services within Washington headquarters, the William J. Hughes Technical Center, the Mike Monroney Aeronautical Center, regional Airway Facilities divisions, and Airway Facilities field offices having the following facilities/equipment Structures and Buildings.

b. An electronic version and distribution report of this directive are available on an Intranet site located at http://aos-ext.amc.faa.gov/ under the “Technical Documentation” heading.

c. To obtain additional hard copies of this publication, contact Printing & Distribution Team, AMI-700B, at (405) 954-3771.

3. DISPOSITION OF TRANSMITTAL. Retain this transmittal.

PAGE CONTROL CHART

Remove Pages Dated Insert Pages Dated iii and iv 11/2/95 iii 11/2/95 iv 2/26/2002 v 11/2/95 v (and vi) 2/26/2002 9 (and 10) 12/30/86 9 (and 10) 2/26/2002 11 and 12 8/8/85 11 8/8/85 13 8/8/85 12 thru 14 2/26/2002 14 12/30/86 15 8/8/85 15 8/8/85 16 1/26/95 16 2/26/2002 21 and 22 12/30/86 21 2/26/2002

22 12/30/86 23 8/8/85 23 and 24 2/26/2002 24 12/30/86

Appendix 1

1 8/8/85 1 and 2 2/26/2002 2 12/30/86

Tue Feb 26 14:50:06 2002

Gregg W. Dvorak Program Director for Operational Support

THIS PAGE LEFT INTENTIONALLY BLANK.

11/2/95 6930.25A CHG 3

Page iii

TABLE OF CONTENTS

Paragraph Page

Chapter 1. GENERAL INFORMATION AND REQUIREMENTS

1. Objective

2. Scope

3. Inspection and Maintenance Program

4. Safety

5.-9. Reserved.

Chapter 2. TECHNICAL CHARACTERISTICS

10. General

Section 1. STRUCTURES

11. Towers

12. Wood Poles

13. Wood Structures

14. Concrete Structures

15. Metal Structures

16.-20. Reserved.

Section 2. BUILDINGS

21. General

22. Construction Types

23. Foundations

24. Floor Systems

25. Walls

26. Ceilings

27. Roof Systems

Section 3. RADOMES

28. Foam Cored Fiberglass Radomes 29.-39. Reserved.

Chapter 3. STANDARDS AND TOLERANCES

40. General

41. Self-Supporting Towers

42. Guyed Towers

43. Wood Poles

44. Safety Climbing Equipment

45. Pole Steps

46.-50. Reserved.

6930.25A CHG 4 2/26/2002

Page iv

Paragraph Page

Chapter 4. PERIODIC MAINTENANCE

Section 1. STRUCTURES

51. With Use

52. Special Conditions

53. Annual

54.-60. Reserved.

Section 2. BUILDINGS

61. Semi-Annual

62. Annual

63. Biennial

Section 3. RADOMES TYPE FA-10800/A, FA-10321, AND FA-10354

64. Every Three Years.......................................................................................... 20-1 65.-70. Reserved.

Chapter 6. MAINTENANCE PROCEDURES

71. General

Section 1. STRUCTURES

72. Safety Climbing Device

73. Turnbuckles

74. Towers

75. Self-Supporting Towers

76. Guyed Towers

77.-80. Reserved.

Section 2. BUILDINGS

81. General

82. Grading

83. Foundations

84. Floor Systems

85. Crawl Space

86. Walls

87. Ceiling Condensation

88. Roofs

89.-101. Reserved.

Section 3. GENERAL MAINTENANCE

102. Concrete

103. Paint

104. Paint Failures

105. Repainting

106. Caulking

2/26/2002 6930.25A CHG 4

Page v (and vi)

Appendix 1. TOWER INSPECTION CHECKLIST Appendix 2. BUILDING CHECKLIST Appendix 3. HISTORICAL RECORD OF ROOF Appendix 4. ROOF MAINTENANCE INSPECTION LIST

LIST OF TABLES

Table Page

5-1. Withdrawn--CHG 4 5-2. Wire Rope Clips 5-3. Caulking Reference Guide

LIST OF ILLUSTRATIONS

Figure Page

2-1. Raised Floor System 2-2. Fiberglass Modular Buildings -Typical Wall Cross Sections 2-3. Built-Up Roof 2-4. Flashing Types 5-1. Transit Arrangement - Self-Supporting Tower 5-2. Vertical Alignment Problem 5-3. Withdrawn--CHG 4 5-4. Withdrawn--CHG 4 5-5. Transit Arrangement - Guyed Towers 5-6. Vertical Linearity Problem 5-7. Guy Tower Alignment - Setup 5-8. Guy Tower Alignment -Adjustment 5-9. Polyester Resin Gel Time

5-10. Structural Crack Undercutting

Chap. 3 Par. 40 Page 9 (and 10)

CHAPTER 3. STANDARDS AND TOLERANCES

40. GENERAL.

This chapter prescribes the standards and tolerances for maintenance of structures and buildings, as defined and described in Order 6000.15A, General Maintenance

Handbook for Airway Facilities. All key performance parameters and/or key inspection elements are clearly defined by an arrow placed to the left of the applicable item.

Parameter Ref.

Par. Standard Tolerance

→ 41. SELF-SUPPORTING TOWERS.

a. Withdrawn--CHG 4

b. Towers ≥ 100 feet tall --alignment error

75b One part in 250 NA

→ 42. GUYED TOWERS.

a. All towers-Guy tension 76b Per facility drawings

±300 lbs. (136kg) (temperature corrected to 60°F) (15°C) of specified initial tension

b. Towers ≥ 50 feet tall

(1) Alignment error 76b One part in 400 NA

(2) Linearity 76b One part in 1000 NA

→ 43. WOOD POLES ............................. Order 6950.18A Order 6950.18A

→ 44. SAFETY CLIMBING

EQUIPMENT.

72 As installed As installed

→ 45. POLE STEPS ................................ Order 6950.18A Order 6950.18A

46.-50. RESERVED

8/8/85 6930.25A

Chap 4 Par. 51 Page 11

CHAPTER 4. PERIODIC MAINTENANCE

Section 1. STRUCTURES

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

51. WITH USE. Check the following items each time they are used.

a. Safety Climbing Device. Inspect, repair and replace device as necessary.

44 72

b. Ladders. Inspect for loose, missing, or deteriorated parts. Repair or replace ladder before using.

NA NA

c. Turnbuckles. Inspect and replace turnbuckles as required.

NA 73

d. Elevated Maintenance Platforms. Inspect to ensure that the platform is level with no loose or projecting boards, grating, nails, bolts, etc., which may cause tripping or stumbling.

Inspect handrails for correct placement, security, and absence of sharp edges or splinters. Report unsafe conditions immediately and insure that repairs are made.

NA NA

52. SPECIAL CONDITIONS. Perform the following actions after all storms, high winds, or heavy ice loads.

a. All Towers.

(1) Grounds. Inspect ground area around tower base for hardware (nuts, bolts, washers) that may have come loose from the tower structure. Replace items in their proper position on the tower.

NA NA

(2) Concrete Foundation. Inspect foundation for cracks. Repair concrete cracks with cement, grout, mortar, or elastomer/plastic patching cement.

NA 102

Chap. 4 Page 12 Par. 52

Section 1. STRUCTURES (Continued)

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

(3) Structural Members. Using binoculars, visually inspect the tower for broken, bent, loose, or missing parts.

Repair damaged or bent parts, and replace parts where necessary.

Secure loose parts and arrange for replacement of remaining damaged parts.

NA NA

(4) Grounding System. Inspect ground straps, cables, and connections for evidence of lightning damage.

Repair and replace parts as necessary.

NA NA

(5) Tower Lighting. Illuminate tower maintenance and obstruction lights to verify that they are in good working order. Repair and replace parts as necessary.

NA NA

(6) Bends and Twists. Observe tower from a distance for vertical bends, curves, or twists.

If any of these conditions exist or are suspect, repair areas.

NA 75a and 76

b. Self-Supporting Towers Observe tower from a distance for vertical alignment. If it is suspected that the tower is leaning, determine amount of leaning using transits, and align tower.

NA 75b

c. Guyed Towers.

(1) Guys. Inspect guy anchors, cables clamps, and hardware for damage. Inspect cable run for unusual sag. Repair and replace parts as necessary. If sag is noted, determine guy tension and adjust guys and align tower if necessary.

NA 76b and c

(2) Vertical Alignment. Observe tower from a distance for vertical alignment.

If it is suspected that the tower is leaning, determine amount of leaning using transits and align tower.

NA 76b and c

Par. 53 Page 13

Section 1. STRUCTURES (Continued)

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

53. ANNUAL.

a. All Towers.

(1) Grounds. Inspect ground area around tower base for hardware (nuts, bolts, washers) that may have come loose from the tower structure.

Replace items in their proper position on the tower.

NA NA

(2) Concrete Foundation. Inspect tower foundation for dusting, spalling, cracking, settling, and tilting.

Inspect grout pads under base plates to insure they are sound. Repair as required.

NA 102

(3) Structural Members. Climb entire length of tower, examining all structural members, antennas, mounts, hardware, and welds for loose or missing hardware, stress cracks, broken or bent members, rust, and corrosion. Tighten loose hardware and replace missing hardware as soon as possible. Replace bent or broken members. Note locations of stress cracks and request regional office assistance to repair. If rust and corrosion damage is extensive, notify sector office to schedule repaint of entire tower. If rust and corrosion damage is limited, clean, prime, and repaint.

NA 105

(4) Grounding System. Inspect ground straps cables, and connections for evidence of lightning damage. Repair and replace parts as required.

NA NA

(5) Tower Lighting. Illuminate tower maintenance and obstruction lights to verify that they are in good working order. Repair and replace parts as necessary.

NA NA

Page 14 Chap. 4 Par. 53

Section 1. STRUCTURES (Continued)

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

b. Self-Supporting Towers

(1) Bends and Twists. Observe tower from a distance for vertical bends, curves, or twists. If any of these conditions exist or are suspect, repair areas.

NA 75a

(2) Vertical Alignment.

(a) Towers < 100 feet tall. Observe tower from a distance. If leaning is suspected, verify plumb of tower using transit. Align tower if needed.

NA 75b

(b) Towers ≥ 100 feet tall. Verify plumb of tower using transit. Align tower if needed.

41b 75b

c. Withdrawn--CHG 4

d. Guyed Towers

(1) Guy Cables. Inspect guy cables, attachment points, and hardware. Repair and replace parts as needed.

NA 76b

(2) Guy Cable Clearance. Inspect area around guy cables to insure clearance from vegetation. Prune back or remove any trees that may damage guy cables.

NA NA

(3) Vertical Alignment.

(a) Towers ≤ 50 feet tall. Verify plumb using level. If problem is indicated, use transit and align tower.

NA 76b

(b) Towers > 50 feet tall. Verify plumb of tower using transit. Align tower if required.

42b 76b

(4) Vertical Linearity.

(a) Towers ≤ 50 feet tall. Observe tower from a distance. If problem is indicated, use transit and adjust.

NA 76b

(b) Towers > 50 feet tall. Verify linearity of tower using transit. Adjust tower if required.

42b 76b

(5) Guy Tension. Determine guy tension, using shunt dynamometers.

42a 76b

e. Wood Poles. See inspection and maintenance procedures of Order 6950.18A.

6950.18A 6950.18A

8/8/85 6930.25A

Par. 53 Page 15

Section 1. STRUCTURES (Continued)

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

f. Wood Structures.

(1) Members. Visually inspect all members for cracks and surface decay.

Sound all members for internal rot. Replace any members showing decay, rot, or extensive cracks.

NA NA

(2) Pole Tops. Visually inspect the tops of support poles. If signs of weathering or cracks are present, seal top of pole with preservative and install a suitable metal pole cap.

NA NA

(3) Joints. Probe all joints with a blunt tool or pocket knife to assure that sound wood exists in all members.

Replace members that show decay or rot at the joints.

NA NA

(4) Fastening Hardware. Inspect all bolts, nuts, and lag bolts for rust and tightness. Replace rusted hardware.

Saturate bolt and hole with preservative before tightening hardware. Where lag bolts will not tighten, use the next larger diameter lag bolt. Inspect bolt holes for elongation and replace members so affected.

NA NA

(5) Paint. Inspect condition of painted surfaces for chipping, peeling, cracking, or separation. Where these conditions exist, probe or drill the wood beneath the paint to ensure that the wood is sound.

Spot paint or repaint structure as required.

NA 105

g. Concrete Structures. Inspect for cracks chipping, spalling, or dusting. Repair areas as required. Note location, length, and width of cracks for comparison during next inspection.

Repeated or increasing cracks indicate problems that require regional engineering assistance.

NA 102

Page 16 Chap. 4 Par. 53

Section 1. STRUCTURES (Continued)

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

h. Metal Structures

(1) Structural Members. Visually inspect members for cracks, breaks, and bending.

Inspect all welds for cracks.

Straighten bent members. Weld or replace cracked members.

Replace broken members.

NA NA

(2) Fastening Hardware. Inspect all fastening hardware (bolts, nuts, screws) for rust and tightness. Inspect bolt locations for elongated holes.

Replace rusted hardware and members with elongated holes.

Tighten all hardware as required.

NA NA

(3) Rust and Corrosion. Inspect structural members for rust and corrosion. Replace severely corroded members. Remove rust, using a wire brush and chemical rust remover. Repaint as required.

NA 105

(4) Paint. Inspect paint for peeling, flaking, or separation.

Spot paint or repaint entire structure if required.

NA 105

54.-60. RESERVED.

Section 2. BUILDINGS

Reference Paragraph Maintenance Activities Standards &

Tolerances Maintenance Procedures

61. SEMI-ANNUAL. Coincidentlly with other PM's, visually inspect entire facility/site to assure integrity and security of all buildings, structures, antennas, etc. In environments where rapid deterioration is possible, visits should be at least quarterly.

NOTE: We believe a facility/site unvisited for a year represents high risk.

Chap. 5 Par. 71 Page 21

CHAPTER 5. MAINTENANCE PROCEDURES

71. GENERAL.

This chapter contains the procedures necessary to accomplish the periodic maintenance activities of chapter 4.

Corrective maintenance procedures for solving problems uncovered during inspections are also provided.

Section 1. STRUCTURES

72. SAFETY CLIMBING DEVICE.

Order 3900.14C, Safety Climbing Equipment at

Existing National Airspace System (NAS) Facilities, and Order 3900.19A, Occupational Safety and Health, require safety climbing devices on all structures over 20 feet high.

The equipment includes a rail attached to the structure (usually the ladder), a sleeve device that attaches to the rail, and a climber safety belt worn by the climber. Use of this equipment when climbing the tower structures is mandatory. Keep the sleeve mechanism and belt clean and store in a clean, dry area. Immediately repair any loose or missing parts.

73. TURNBUCKLES.

Forged steel, galvanized turnbuckles are furnished and incorporated in each guy cable installed on steel towers.

When the turnbuckle, under load, is fully extended, no less than 4 threads must protrude into the barrel. Assure that the jamb nuts are tight and secure. Check that each turnbuckle is secured with a safety tie, galvanized number 9 AWG wire or equivalent, passed through the upper and lower eye and through the turnbuckle body. This should form a "figure eight" and be neatly secured. Inspect the turnbuckles carefully for signs of rust and corrosion, particularly the threaded area and load-bearing surfaces.

Remove rust with a wire brush or other means and apply water-insoluble penetrating-silicone-corrosion inhibitor and lubricant. As soon as a tough fiber forms over the surface of the silicone, apply a layer of hard grease over the entire turnbuckle to exclude moisture. If the corrosion is severe, replace the turnbuckle and associated hardware.

74. TOWERS.

a. General. Wind and other natural elements adversely affect towers. Wind vibrations cause fatigue in members, loosen bolts and nuts, crack members and welds, and chafe attached components. High winds may result in broken members and guys, twisted and tilted towers, and pulled anchors. Members may deform under the loads of ice and snow. Brittleness of members is common due to the annealing effects of vibrations and cold/heat extremes.

Lastly, exposure creates rust and corrosion, which weaken members thereby decreasing the load-handling capability of the tower. Maintenance personnel should be alert to the stresses that towers are subjected to, and should inspect the tower on every climb. Defects noted on towers shall be corrected immediately, where feasible, as inaction may lead to complete failure (collapse). Repairs that cannot be made immediately will be scheduled for priority action.

b. Data and Drawings. Current data and drawings for each type tower structure shall be available at each facility.

If the installation varies from that shown on the as-built drawings, mark the correct information in red pencil on the appropriate drawing and submit it to the regional office for an official change.

75. SELF-SUPPORTING TOWERS.

a. Bends and Twists. Bends and twists in self-supporting towers indicate that structural damage has occurred. Use the following procedures to correct the problem. Engineering assistance from the regional or sector office should be requested.

(1) Set up transit at a distance from the tower base equal to the tower height. (see figure 5-1.) Line up the transit on the face of the tower, scan the length of the tower, and identify the area of the tower involved. Relocate transit to observe tower at a 90° angle from the first position and repeat observation.

(2) Climb the tower up to the affected area and inspect for loose or missing bolts, elongated holes, and bent, broken, or missing members.

(3) Replace broken, bent or missing members.* *

6930.25A CHG 1 12/30/86

Page 22 Chap. 5 Par. 75

Figure 5-1. Transit Agreement - Self-Supporting Tower

(4) Locate original hole centers, using tower drawings if necessary, and redrill holes to the next larger bolt size.

(5) Using a chain hoist, drift pins, etc., force the tower into alignment.

(6) Replace missing bolts with that specified on the tower drawings. Use oversize bolts on holes that have been redrilled. Tighten all bolts to specifications on drawings.

b. Vertical Alignment. The vertical alignment of a tower may be thought of as a measurement of tower "leaning". (See figure 5-2.) Leaning of a self-supporting tower is normally caused by settling of the foundation.

(1) Measurement. The following procedure provides for measuring deviation from true vertical of towers in winds of 5 miles per hour (8 km/hr) or less.

(a) Set up transit as shown in figure 5-1.

(b) Set the vertical hair of the transit on the edge of the tower leg at the top. Decrease elevation of transit until base of tower leg is sited. Measure lateral displacement of leg from vertical hair and record as X1.

(c) Repeat steps (a) and (b) for second transit location and record displacement as X2.

(d) Total deviation from vertical, X, may be calculated from 2

1 XXX += . Allowable deviation is a function of tower height, and must be less than one part in 250.

(2) Correction. If deviation from true vertical is greater than allowed, level the foundation base plates as follows:

(a) Check the relative elevation of the tower foundation by use of the level and level rod. Set the rod on top of each leg base plate and read the rod. (Interpolate to 1,000ths.) Assuming this elevation of the first base plate as the base, compare rod readings of other base plates noting that all should be the same elevation. Record all readings (to 1/1000) and compare findings with the base reading, noting the difference (+ or -).

(b) From the above data, determine the total deviation, direction tower has moved, and the extent of adjustment necessary.

(c) Minor foundation settlement can be adjusted by raising or lowering the leg base plate by the use of the screw jack and shims. If this adjustment is beyond the travel limits of the anchor bolts, contact the region for engineering assistance. After leveling all base plates, repeat measurement procedure to verify that the tower is again in alignment.

(d) Record the thickness of shim material added to level the legs so a record may be established to determine if the settlement is continuing. Record new elevation readings for all legs after adjustment.

Chap. 5 Page 23 Par. 75

Figure 5-2. Vertical Alignment Problem c Withdrawn--CHG 4

76. GUYED TOWERS.

a. General. Problems with guyed towers are normally caused by damaged structural members, misadjusted guys, or failure of guys or guy anchors. This paragraph provides measurement procedures for verifying the standards of chapter 3 for guyed towers and corrective maintenance procedures to resolve problems. There are two items of importance maintenance personnel must keep in mind when performing corrective maintenance on guyed towers.

Figure 5-3. Withdrawn--CHG 4

(1) The positional parameters for guyed towers, alignment, linearity, and twists, are interactive. Therefore, displacing a tower to correct an alignment problem, if done incorrectly, may cause a linearity problem.

(2) Any displacement of the tower to correct a position problem will affect guy tensions.

b. Inspections/Measurements.

(1) Cable Inspection. While on the ground, carefully inspect each guy cable for rust, corrosion, or unusual sag. Check guy attachments for chafing of cables and thimbles. Check for indications of rust in the cables, thimbles, Page 24 Chap. 5 Par. 76

Table 5-1. WITHDRAWN--CHG 4

Figure 5-4. Withdrawn--CHG 4 clips, seizing, serving clips, and attaching components.

Check carefully for any sign of cable slippage and determine that all clips are properly installed, spaced, and secure. When the inspector climbs the tower making the structural inspection, all guy intermediate and top connections shall be individually inspected for the above items. The guy connections at outriggers on microwave towers require visual inspection only. Replacement of guys shall be made by steel riggers using guy material specified in Lower drawings.

(2) Measurement of Vertical Alignment. Use the following procedure if winds are 5 mi/hr or less.

(a) Set up transit near an outside guy anchor.

(see figure 5-1.)

(b) Set the vertical hair of the transit on the edge of the tower leg at the top. Decrease elevation of transit until base of tower leg is sited. Measure displacement of leg from vertical hair and record as X1.

Appendix 1

APPENDIX 1. TOWER INSPECTION CHECKLIST

Date ___________________________ Facility _________________________ Tower Location/Identification _______ Tower Manufacturer _______________ Tower Height ____________________ Tower Type _____________________

Self-Supporting ________________

Guyed ________________________ Inspected By _____________________

1. INSPECTION.

a. Grounds

(1) Clean ____________________

(2) Items Found ____________________

(a) List ____________________________________________________________

b. Foundation

(1) No problems ____________________

(2) Problems

(a) Dusting ____________________

(b) Spalling ____________________

(c) Cracking ____________________

1 Extent (Describe) _______________________________________________

(d) Settling ____________________

1 Amount _______________________________________________________

(e) Tilting ____________________

1 Amount _______________________________________________________

c. Structure

(1) No Problems ____________________

(2) Problems ____________________

(a) Loose Hardware ____________________ 1 Describe ______________________________________________________

2 Corrected ____________________

(b) Missing Hardware ____________________ 1 Describe ______________________________________________________

(c) Stress Cracks ____________________

1 Location ______________________________________________________

(d) Broken Members ____________________ 1 Locations ______________________________________________________

Appendix 1

(e) Bent Members _____________________ 1 list ____________________________________________________________

(f) Rust/Corrosion _____________________

1 Extent _________________________________________________________

(g) Paint _____________________

d. Grounding System

(1) Okay _____________________

(2) Damaged _____________________

e. Lighting System

(1) Operates _____________________

(2) Bad _____________________

f. Bends and Twists

(1) No Problem _____________________

(2) Observed _____________________

1 Describe ________________________________________________________

g. Vertical Alignment

(1) Deviation

(a) Transit No. 1 _____________________

(b) Transit No. 2 _____________________

(c) Total Route-Sum-Square √ (a) 2 + (b)2 _____________________

(d) Tower Height _____________________

(e) (c)/(d) _____________________

(f) Specification Limit (1/250, 1/400, 1/600) _____________________

h. Withdrawn--CHG 4

i. Withdrawn--CHG 4

j. Guy Cables

(1) No Problems _____________________

(2) Problems _____________________

(a) Sag _____________________

(b) Chaffed Cable _____________________

(c) Clips Not Installed Properly _____________________

(d) Rust _____________________ j-1. Engine Generator

(1) No Problems _____________________

(2) Problems _____________________