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43 CHAPTER 6 Approval and Commercialization Study 6.1. Approval Process for tire/ground interface. The normal process is intended for New Arrestor Development application to a full spectrum of design concepts. It requires that a manufacturer undertake (1) initial data collection, (2) The researchers engaged in discussions with both the FAA feasibility calculations, (3) first-principles computer modeling, and manufacturers regarding the approval of new arrestor and (4) small-scale testing. The results would be submitted systems. Currently, only one EMAS system has obtained FAA to the FAA as an application for a Cooperative Research and approval, and new entrants to the arrestor market often cannot Development Agreement (CRDA). The CRDA would then determine what steps to take toward gaining approval for their facilitate full-scale aircraft testing, which should be required new designs. All parties concurred that a process is needed for systems fundamentally dissimilar from the existing EMAS whereby new arrestor systems can be developed and gain FAA design. After testing, the manufacturer would be required to approval. demonstrate the ability to predict system performance with As a starting point, the FAA has stated that the essential a computer model, as applied to different sizes and types performance requirements contained in AC 150/5220-22a of aircraft. Finally, the manufacturer would apply for FAA will be required for other arresting system alternatives. The approval of the system. FAA has determined that the Airport Engineering/Airport Safety and Standards division, AAS-100, will act as the primary point of contact for companies submitting concepts. 6.3. Equivalent Approval Process Discussions with the FAA generated a number of ideas regarding the approval process. This report outlines a poten- Obviously, the normal process would require substantial tial approval process, intended as a starting point for ongoing financial investment and involve several complex steps. For dialogue and modification. some applicants, these factors could preclude involvement, thus Based on the historical development of the EMAS concept stalling potential improvements to the current EMAS approach. and the technical issues involved in arrestor systems, a two- The "equivalence" process of Figure 6-3 allows for a simplifica- branch approval process is proposed (Figure 6-1). A normal tion to the normal approach if certain conditions are met. approval process would be required for arrestors substantially The equivalence process would require that the new concept different from the current EMAS design. For systems that constitute an equivalent to the current EMAS design at a do not differ substantially, however, a shorter "equivalence" mechanical level. It is restricted to replacement materials process is recommended. When a manufacturer submits a that are laid out in a geometrically similar bed and produce a concept to the FAA, the first step would require identifying dynamically analogous load on the landing gear. An aggregate whether or not the system qualifies as a design equivalent to system, for example, would not constitute such an equivalent, the current EMAS or constitutes a different dynamic approach. since it has other physical mechanisms at work than a crushable This determination will then dictate what further steps the foam material (Section 7.4). Meanwhile, another crushable manufacturer would need to take for approval. foam could constitute such an equivalent. To date, many crush- able materials have been proposed as alternatives to cellular cement (Sections 7.3 and 7.4). The cellular cement could be 6.2. Normal Approval Process replaced with a different crushable medium of similar prop- The "normal" approval process would require the stages erties and still obtain analogous arresting performance. outlined in Figure 6-2. This process does not assume that Further, the term "equivalent" is not intended to prevent an arrestor is passive, nor that it engages the aircraft at the new materials from superseding cellular cement. It requires