SOW CHA ATCT LPGBS.pdf

Writer: Ashton Brown Rev: D Date: 02/09/2024

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Federal Aviation Administration

LPGBS

LIGHTNING & SURGE PROTECTION,

GROUNDING, BONDING & SHIELDING

CHA ATCT LPGBS Site Survey Report \ SOW

Prepared by: LPGBS Program Office AJW-22

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1-PURPOSE:

The Lightning Protection Grounding, Bonding, and Shielding (LPGBS) system at the Chattanooga, TN (CHA) ATCT will be optimized to make the ATCT more robust during severe weather. Second, the lightning protection system on the tower building will be optimized. All site areas disturbed during demolition and construction shall be repaired and restored to original condition. All work will be done in accordance with FAA-STD-019F Chg. 3 and NFPA 780.

2-BACKGROUND:

The LPGBS Program Office conducted asset site surveys at CHA in conjunction with the active LPGBS construction project progress inspection of the ATCT. This visual survey was focused on:

• Exterior LPGBS conditions, not meeting FAA-STD-019F Chg. 3.

3-ACTIONS TAKEN:

On July 5, 2023, the LPGBS Group visited the site, took pictures, reviewed drawings, and examined the LPGBS infrastructure of the site. The LPGBS Group prepared a list of observations from the site as well as items that do not meet FAA-STD-019F Chg. 3, which should be addressed.

The site is located at Lat/Lon: 35.02958 / -85.200534 .

OBSERVATIONS OF ASSETS SURVEYED AND RECOMMENDATION:

#. Observation. Recommendations.

CHA ATCT, Exterior LPGBS:

1. At the ATCT roof level (95 ft tower height), there are 4 – 12 ft long pole masts on the roof surface membrane with attached copper (pointed) air terminals fastened. Air terminals are shorter than the antennas that are attached to parapet. [Fig. 1]

a. Install existing air terminals on 4 new 20 ft pole masts.

2. At the ATCT roof level, there is no equalization ring around the parapet. There are 2 down conductors penetrating through the membrane roof of the ATCT. [Fig. 2]

a. Demo the 2 existing down conductors that are penetrating through the penthouse roof.

b. Install 4 new tinned copper Thompson 506 or equivalent lightning down conductors to the existing air terminals that are fastened on the new 20 ft pole mast.

c. Fasten the down conductors on the 20 ft pole mast at least every 3 feet.

d. Install a new tinned Thompson 506 or equivalent equalization ring on ATCT roof parapet.

e. Interconnect each of the 20 ft pole mast down conductors to the new equalization ring using T-style method (see Exterior Illustrative method).

f. Install 2-foot horizontal air terminals at each corner of the ATCT roof parapet (total of 8).

g. Bond each of the 6-antenna bases on the ATCT roof with a minimum #2 AWG conductor to the new equalization ring. Use UL Listed U-Bolt connection.

h. Bond the metallic hatch base to the equalization ring with a minimum #2 AWG and provide jumper “flexible 2-hole ground strap” between metallic hatch base and the hatch door.

i. Bond from the equalization ring to the single metallic vent with a minimum #2 AWG.

j. Bond from the equalization ring the metallic water drain with a minimum #2 AWG.

k. From the equalization ring on the parapet, using cross over style connection method (see Exterior

Illustrative method) tie in the 4 new down conductors.

http://maps.google.com/maps?q=35.0295804%2C-85.2005336

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l. Down conductors are to be installed along building corners equally spaced apart.

m. Fasten down conductors at every 3 ft.

n. Ensure all conductor bend radius are not bent less than 8 inches.

o. All bonding terminations are to be by a UL 96 irreversible hydraulic crimp connection.

3. At the ATCT Catwalk level, no equalization or horizontal air terminals installed. [Fig. 3] [Fig. 4]

a. Install equalization lightning conductor ring on top of catwalk rail.

b. Install a total of 8 horizontal tinned copper air terminals, 2 ft long by ½ in. diameter at every

Catwalk rail corner.

c. Bond the exposed metal hood with a minimum #2 AWG on located on the Catwalk with a tinned

Thompson 506 or equivalent conductor to the equalization ring.

d. Bond the metallic door frame with a minimum #2 AWG conductor to the equalization ring.

e. Bond the door frame to the door with a flexible 2-hole ground strap.

f. Interconnect the 4 new down conductors with the new equalization on Catwalk level using cross-over style connection method (see Exterior Illustrative method).

4. No intermediate equalization ring (approximately 50 feet above ground).

a. At the tower shaft intermediate levels, install an equalization loop approximately 50 ft from the base of the tower.

b. Interconnect new down conductors with the equalization loop using Cross-over connection method (see Exterior Illustrative method).

5. No equalization ring around the tower at the base building height (approximately 12 feet above ground)

a. At the tower shaft base building height, install an equalization loop approximately 12 ft from the base of the tower.

b. Interconnect this equalization ring with the equalization ring on the roof of the base building.

c. Interconnect new down conductors with the equalization loop using Cross-over connection method (see Exterior Illustrative method).

d. Transition the new down conductors by use of hydraulic crimp method to a 4/0 AWG conductor at 7 ft. above grade.

e. Install each of the 4/0 AWG conductors in a 1 in. schedule 40 PVC 6 ft above grade and 1 foot below grade and exothermically weld conductors to the EES.

EXTERIOR Illustrative Example:

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Lightning Protection System Main Conductor Connections – Illustrative Example

*Observation Photo Log:

Figure 1: ATCT Tower air terminal Figure 2: Roof of ATCT Figure 3: ATCT Catwalk level

Figure 4: Catwalk entry

Antenna taller than air terminal

1 of 2 existing down conductors penetrating through roof

Missing equalization parapet

Air terminal

Missing equalization and air terminals

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General Recommendations:

1. All mechanical connections shall follow FAA-STD-019F chg. 3 section 4.2.3.4.2 Bolted Connections and its sub-sections, Figure 1 Order of Assembly for Bolted Connections, and Table 2 Connection Torque Requirements for Bolted Bonds.

2. Surface preparation and refinishing for bonding shall follow FAA-STD-019F chg. 3 section 4.2.4 and its sub-sections.

3. Exothermic Welds Safety Note:

a. In a staffed operational facility:

i. Use exothermic weld when the connection is pre-made and performed beyond 20 horizontal feet from the facility.

ii. Use hydraulically crimped connections that meet the requirements of section 4.2.3.2 as an alternative to exothermic weld.

b. At locations where exothermic weld creates hazardous condition, such as near fuel tanks, use hydraulically crimped connections that meet the requirements of section 4.2.3.2 as an alternative to exothermic weld.

4. Replace the rest of the existing exterior ground connections star washers with load distribution washers while applying the Table below for the number of washers and torque requirements. (There should be no more than 50 existing one- and two-hole lug ground connections that need 1/2” load distribution washers to install). Also, smaller hardware (bolt, nut, flat washer, and Belleville washers) can be used to replace existing hardware it torqued properly.

Contract Requirements:

Standards

1. FAA-STD-019F Chg. 3

2. NFPA-780

Construction Schedule

Hours of work

It is anticipated that this work will take place during both operational and non-operational hours (Hours of Operation for CHA ATCT are 0600 – 2350) in order to minimize interference with air traffic operations. The following areas shall have work planned and scheduled for non-operational hours only:

1. The ATCT CAB roof

2. The Terminal Radar Approach Control Facility (interior to the CHA base building)

Any work affecting areas that are outside of the building and / or at a distance from the operational areas, can be scheduled for daytime hours of 0700 – 1530.

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Required Submittals

1. Pre-construction submittals

1. Proposed project schedule with work hours

2. Site Safety Plan

3. Contractor’s list of key personnel with role and contact information

4. Crane plan (if applicable)

5. Man lift plan (if applicable)

6. Shop Drawings

7. Detailed materials list

2. Post construction submittals

1. Final installation shop drawings (as-builts)

2. Installation Photos

3. One year warranty