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85 Table 9-8. Estimated costs to establish glass Order 5200.9. Based on other fielded applications for glass foam foam arrestor, 150 x 300 ft, assuming survey material, life cycles of 20 years should be realistic, with some average costs for current EMAS, units of past applications indicating that it can last as long as 50 years. millions USD. This effectively reduces the life-cycle cost of the concept. Since the installation costs are expected to be similar to the existing Cost Category Glass Foam Current System EMAS EMAS, the elimination of a 10-year bed replacement would effectively trim $3.5M of present-value life-cycle costs. Site Preparation $ 2.17 $ 2.17 However, the top cover layer applied to the material must Installation $ 5.49 $ 6.03 also be considered. Polymer coatings and plastic lids can Cost to Establish $ 7.65 $ 8.19 degrade when exposed to ultraviolet radiation and varying Percent of EMAS 93% weather conditions. Overhaul may be required to replace or repair the top material periodically. standard 10-year replacement interval for an EMAS, which translates into present-value life-cycle costs. Such a replace- 9.6.5. Repair ment could arguably be unnecessary for this arrestor concept Repairs after an overrun would parallel those of the current (Section 10.6.4). Eliminating the assumed 10-year replacement EMAS design. Damaged sections of glass foam material would could effectively trim about $2.6M of present-value life cycle require removal and replacement after aircraft extraction. costs (based on the EMAS replacement cost estimates of the survey). 9.7. Transition to a Fielded System 9.6.3. Maintenance In order to transition the glass foam concept to a fielded system, the following additional development steps may be The glass foam material is expected to have a superior advisable. durability when compared with cellular cement. Glass foam does not exhibit the tendency to crumble during handling that occurs with cellular cement, nor does it exhibit overt 9.7.1. Low Material Density Calibration sensitivity to moisture due to its closed cell microstructure. As shown in the example arrestor beds of Table 9-6 and Many industrial applications of glass foam materials indicate Table 9-7, the compressive strengths for optimal designs that long service life is possible with little degradation as long ranged from 17 to 53 psi. Since the material tested and cali- as mild protective measures are taken. brated during the research had a nominal strength of 55 psi In the monolithic version of the concept, joint tape/caulk with a 6-pcf density, the fielded material will be softer and maintenance would not be required. Annual maintenance lighter. To estimate the needed density and strength, the could be limited to upkeep of the required yellow chevron metamodel data was simply scaled, which was an appropriate markings on the arrestor. simplification. However, in migrating to a fielded system, several standard 9.6.4. Replacement and Overhaul densities would probably be selected to provide flexibility dur- ing the design of actual arrestors (currently done with EMAS). It is not anticipated that replacement of the bed would be For each density, some testing would be required to generate required after 10 years, as anticipated for an EMAS in FAA calibration data. The foam glass material model would require minor adjustments to compensate for the alterations. Fresh Table 9-9. Estimated costs to establish glass metamodel data should then be generated such that data foam arrestor, 150 x 300 ft, assuming Order scaling would no longer be required in the arrestor design 5200.9 costs for current EMAS, units of process. millions USD. Cost Category Glass Foam Current 9.7.2. Cover Layer Design System EMAS Site Preparation $ 0.68 $ 0.68 Two major cover-layer design concepts are possible: Installation $ 5.49 $ 3.83 1. Plastic lids, applied to the block version of the concept, or Cost to Establish $ 6.17 $ 4.50 2. Spray-on or roll-on polymer coating, applied to the mono- Percent of EMAS 137% lithic concept.