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November 29, 2018 <br /> paint process. The region defined by the decorative paint follows the <br /> same requirements as the balance of the hangar. Specifically the Class <br /> Division 1 boundary is defined by the 2% LEL boundary predicted by the <br /> CFD analysis plus 2.5 feet. An additional 5 feet is provided for establishing <br /> the Class I Division 2 boundary. <br /> Adjacent to wings <br /> Ventilation of the wings is designed to minimize the hazardous area <br /> boundary distance in front of the leading edge, but the distance aft of the <br /> trailing edge is greater as a result. <br /> The distance from the leading edge of the wing to the 2% LEL boundary <br /> predicted by the CFD analysis varies by location but a distance of 6 feet <br /> was found to be conservative for this area. Applying an additional 2.5 feet <br /> for plume dispersion results in a Class I Division 1 boundary of 8.5 feet. <br /> This was determined to be an appropriate boundary for Class I Division 1, <br /> with 5 additional feet for Class I Division 2. <br /> The distance from the wingtip to the 2% LEL boundary predicted by the <br /> CFD analysis varies by location but a distance of 3.5 feet was found to be <br /> conservative for this area. Applying an additional 2.5 feet for plume <br /> dispersion results in a Class I Division 1 boundary of 6 feet. This was <br /> determined to be an appropriate boundary for Class I Division 1, with 5 <br /> additional feet for Class I Division 2. <br /> The distance from the trailing edge of the wing to the 2% LEL boundary is <br /> predicted at 15.75 feet. Applying an additional 2.5 feet for plume <br /> dispersion results in a Class I Division 1 boundary of 18.25 feet with 5 <br /> additional feet for Class I Division 2. This was simplified for field <br /> visualization by placing the Class I Division 2 boundary at building column <br /> 10, and the Class I Division 1 boundary 5 feet south of building column 10. <br /> Overall boundary definition <br /> The prescriptive requirements from the 2017 NEC for fueled aircraft and open <br /> containers was combined with the recommendations based on the CFD analysis <br /> to produce the simplified hazardous boundary area drawings 45-03-E600-1 Rev <br /> A, 45-03-E600-2 Rev A, and 45-03-E600-3 Rev A drawings. <br /> Current Request <br /> If you concur with our request, please acknowledge acceptance by providing a letter <br /> stating the attached drawings for the 45-03 define the Class I Division 1 and Class I <br /> Division 2 boundaries for implementing NEC requirements. <br /> Page 9 of 1;) <br />