It is not the intent of this chapter to present information on  every type of material or hardware ever used in parachutes.  For very detailed specifications on a broader range of  materials used in current production parachutes, as well as  obsolete and military surplus parachutes, there are additional  reference sources, such as “The Parachute Manual” by Dan  Poynter. The purpose of this chapter is to present as much  information on the essentials of modern materials seen in  today’s parachute systems. Many riggers operate quite successfully with a basic level  of material knowledge in their proverbial tool kit. There are  certain materials that are commonly used on most parachute  systems, and in dealing with these on a regular basis, the  rigger becomes very familiar with their characteristics and  proper application. It is fundamental that the rigger know  their correct type, nomenclature, strength, and common use.  In dealing with other riggers, manufacturers, and suppliers,  the rigger is then able to identify the referenced material in  order to obtain the appropriate repair part or describe the use  of the material to others. All of this is part of the parachute  rigger’s lexicon, required to communicate their needs and  accomplish the required tasks. All certificated parachute systems built under government  approval programs require most, if not all, materials used  in their construction to have some form of specification  approval. The most common of these systems is the military  specification (MIL-SPEC) system. In addition, there are other  government specifications, such as Federal Standards, and  commercial specifications in use. The MIL-SPEC system  is the one with which most riggers are familiar. Contrary  to popular perception, not all materials for use in parachute  manufacturing must be MIL-SPEC. Any specification may be  used, provided that the manufacturer can prove compliance  with this specification, and that the specification is acceptable  to the Federal Aviation Administration (FAA) for use in  the parachute system. As a rule, the MIL-SPEC system has  proven the most readily available and accepted method. In recent years, the government has been accepting more  commercial specifications in lieu of MIL-SPEC items. In  2002, the Parachute Industry Association (PIA) adopted  approximately 270 parachute-related specifications, drawings,  standards, and test methods. The PIA takes responsibility for  the continued maintenance and revision of these specifications.  As the specifications are revised, they keep their original  identification number, but the PIA prefix precedes them.  For instance, MIL-W-4088 webbing becomes PIA-W-4088.  Through the involvement of the PIA Specifications Committee,  the revised specifications, including new digital drawings, are  made available to the industry. 3-2 Specifications Fabrics The MIL-SPEC or PIA-SPEC system of identification  consists of the initial letters MIL or PIA with a middle letter  such as W for webbing or wire, then the identification or  serial number of the specification. In addition, there may be  a revision letter, such as A, B, C, D, etc. In the case of PIA- W-4088D, this is the fourth revision.  The materials and hardware listed herein are only a small  part of those available, but the most commonly used in  the majority of today’s rigging profession. By learning  the specifications and uses of these materials, the rigger  establishes a sound basis for the repair and maintenance of  modern parachutes.  To promote the latest specifications, the PIA nomenclature  is called out unless otherwise noted. In the past, the common  method to denote the various types of webbings, cords, etc.,  was to use the Roman numeral for the type (e.g., Type VIII  for Ty-8, Type XVII for Ty-17). For this handbook, the  standard is the Arabic numeral (e.g., Ty-7). Many of the figures in this chapter use a neutral background  with an XY grid for reference. The numbers are in one-inch  increments for a proportional reference. Nylon is the predominate fabric used in the manufacture  of parachutes. Chemically speaking, nylon is made of  repeating units linked by amide bonds and is frequently  referred to as a polyamide (PA). It was invented in the late  1930s by Wallace Carothers while conducting research  at DuPont. There are many different kinds of nylon and  some of the major differences include the weave, weight,  and finish. The various types of materials include canopy  fabric, pack cloth, tapes, webbings, mesh, elastic fabrics,  stiffener materials, and foams.  Canopy fabrics are primarily ripstop nylon. Ripstop weave is  a plain weave with heavier threads woven into the material at  right angles resulting in a boxlike pattern. The heavier thread  and the unique weave results in ability of the threads to slide  over one another inhibiting the tearing process and results in  stronger fabrics.  [Figures 3-1  through  3-6] The composition of most containers is from either nylon duck  (Para-pack) or Cordura $^{®}$. Para-pack has a smooth somewhat  shiny finish; Cordura has a matte, more rugged appearance.  Both are sturdy and long lasting. Most sport containers also  utilize a thin foam lining on the inside of the flaps to smooth  out the fabric and absorb wear and tear. Other fabrics, such  as mesh, Spandex$^{®}$, and ballistic fabric, serve specialized  purposes.  [Figures 3-7  through  3-16]