Parachute Rigger HandbookFAA-H-8083-17A
Chapter 03
Materials
32 pagesPages 3-1–3-32
Introduction
The correct identification and use of the various materials in parachute manufacturing and repair are of vital importance to all riggers. Just as important as acquiring knowledge of tools and machines, knowing and using the correct terminology for materials is essential to the rigger’s job comprehension. In doing repairs or alterations, the rigger must be able to identify the types of materials used in order to duplicate the original manufacture and to ensure the correct level of safety necessary. Some materials may look similar, but there can be subtle differences between them that make a major difference in their strength or durability.
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.
Specifications
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.
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.
Fabrics
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]
Figure 3-1. Cloth, parachute, nylon, Type-1.
Figure 3-2. Cloth, parachute, nylon, Type-3, 30-50 CFM.
Webbing and Tapes
While many webbings and tapes have the same specifications, they still have different designations. The difference is a common rule of thumb where anything 1 inch or wider and over 1000-lb strength is webbing. Anything less is a tape. There are, however, some examples that fall outside of this criterion. The primary use for webbing is for load bearing purposes, such as harnesses and risers. Tapes are for use as support and reinforcing for canopies and containers. Most webbing and tapes, when manufactured, are left in their natural, untreated condition (condition U), or treated with a synthetic resin named Merlon, for stiffness (condition R). A newer treatment, called “Ecco,” is similar to a light condition R. This is a newer treatment that is ecologically friendlier than using Merlon. It also results in a medium stiffness that is easier to sew. This is for use primarily in the lighter weight tapes, such as 3⁄4" Ty-3. Recently some harness/container manufacturers have begun to replace 3⁄4" Ty-3 binding tape with 7⁄8" Ty-3 because modern container designs are getting thicker with the application of more stiffeners and more padding. There are pros and cons to this trend.
Figure 3-3. Cloth, parachute, nylon, Type-1, Lo-Po, .5-3 CFM.
Figure 3-4. Cloth, parachute, nylon, Type-1, zero porosity.
Figure 3-5. Cloth, netting, nylon (marquisette).
Figure 3-6. Cloth, mesh, large hole, nylon.
Webbing Selection
When a repair requires replacement of webbing and tapes, care must be taken to use the correct webbing or tape for the job. Generally, there are two types of webbings used in industry: needle weave and shuttle weave. Remember this: “Needle Never, Shuttle Sure.” This is because needle weave webbing is rarely, if ever, used in personnel parachute assemblies.
Figure 3-7. Cloth, duck, nylon (Para-pak).
| Specification: | PIA-C-7219 class 3, 7.25 oz, 420 denier |
| Tear/breaking Strength: | 20 lb/275-325 lb |
| Identification: | 1-1 plain weave |
| Common Use: | Sport and military containers |
| Comment: | Has a urethane coating on the inside |
®
Figure 3-8. Cloth, nylon, Cordura .
The reason for this limitation is because of the reaction of the webbing when “edge nicked” while under tension. In tests of the most advanced needle weave products several years ago, it was dramatically demonstrated, numerous times, that the webbing would fail catastrophically when the edge was nicked with sharp metal while under tension.
Figure 3-9. Cloth, nylon, Cordura®.
Figure 3-10. Cloth, duck, nylon, ballistic.
The two types may be identified by comparing their edges. Fold the webbing in half and align the selvage edges. They should be identical in weave. If they are, then it is shuttle weave and acceptable for use. If they are not, then it is needle weave.
Figure 3-11. Elastic fabric, Spandex®.
Figure 3-12. Pressure sensitive adhesive tape—ripstop tape.
One should never be substituted for the other in a repair. The rigger should have material certification and lot tractability for any materials used in the repair. The material certification should additionally identify the type. [Figures 3-17 through 3-32]
Figure 3-13. Foam, Volara®.
Figure 3-14. Foam, ¼" closed cell athletic foam.
Figure 3-15. Foam, ester liner.
Figure 3-16. Oxford cloth, 200 denier.
Figure 3-17. ⁹⁄16" Type-1 Webbing.
Figure 3-18. 3" Type-4 Webbing.
Figure 3-19. Type-6 Webbing.
Figure 3-20. Type-7 Webbing.
Figure 3-21. Type-8 Webbing.
Figure 3-22. Type-12 Webbing.
Cords, Lines, and Threads
The most common uses of cord and lines are the suspension lines of the canopy. There are many different types in use. Today, the most common are nylon, Dacron, and Spectra®. The rigger needs to know the different types and their uses. Each may have special techniques to work with them.
Figure 3-23. Type-13 Webbing.
Figure 3-24. Type-17 Webbing.
Almost all cords, lines, and threads are constructed of Nylon, again because of its inherent strength and relative elasticity. [Figures 3-33 through 3-43]
Figure 3-25. Type-3 Tape.
Figure 3-26. Type-4 Tape.
Figure 3-27. Tubular webbing.
Figure 3-28. Type-1, 1" Parachute construction tape.
Figure 3-29. Tape, polyester, 2".
Figure 3-30. Tape, nylon, 3".
Figure 3-31. Kevlar® tape.
Figure 3-32. Cotton elastic webbing.
Figure 3-33. Cord, nylon, Type-2 and Ty-3.
Figure 3-34. Cord, nylon, Type-1a.
Figure 3-35. Cord, nylon, Type-2a.
Figure 3-36. Cord, Nylon, Type-5.
Figure 3-37. Cord, Dacron.
Figure 3-38. Cord, Kevlar®.
Hardware
Hardware, as defined in the context of parachutes, is “all metal parts associated with parachutes, their systems, and their suspended loads.” Most riggers identify hardware as the snaps, adapters, rings, links, and releases commonly used on harnesses. In addition to these components, other hardware includes items such as lightweight links and snaps, ripcords and handles, stiffeners, grommets, springs, and snap fasteners. [Figures 3-44 through 3-79]
Figure 3-39. Cord, Spectra®.
Figure 3-40. Cord, Spectra®.
Most load bearing hardware consists of drop-forged alloy steel, sheet alloy steel, or forged aluminum alloy. Lightweight hardware may be stamped from the sheet alloy steel, or in rare instances, cast. Ripcord pins are cold forged. The majority of the load bearing hardware is forged carbon steel with either cadmium or zinc plating.
Figure 3-41. Cord, Vectran® LCP.
Figure 3-42. Cord, HMA.
In recent years, there has been a movement to produce newer design hardware of stainless steel. This removes the problem of plating and the environmental problems associated with it. However, stainless is harder on the forging dies and the finishing processes take longer. Consequently, stainless hardware is generally more expensive than carbon steel.
Figure 3-43. Cord, elastic.
Figure 3-44. Cord, nylon, 5 cord Belbob.
All specification hardware has the appropriate number stamped or marked on it. The MS prefix is on those with the MIL-SPEC certification. All with the newer PIA certification have the mark with the PS (Parachute Standards) prefix. [Figure 3-64] Most of the current hardware has the mark with the MS prefix. As current stocks deplete, the mark on new production is with the PS prefix.
Figure 3-45. Thread, nylon.
Figure 3-46. A. Thread, cotton, 24/4; B. Thread, cotton, 3-cord.
Figure 3-47. Thread, nylon, flat braided (supertack).
Figure 3-48. Snap, B-12.
Figure 3-49. Ejector snap, non-adjustable.
Figure 3-50. Snap, quick fit.
Figure 3-51. Snap, quick fit ejector.
Figure 3-52. Snap, parachute chest-type pack.
Figure 3-53. Snap, quick connector, parachute harness.
Figure 3-54. “D” ring harness, old style.
Figure 3-55. Adjuster, oval ring.
Figure 3-56. “D” ring harness, new style.
Figure 3-57. “V” ring, quick fit, shallow frame.
Figure 3-58. “V” ring, quick fit, large frame.
Figure 3-59. Adapter, quick fit, small frame.
Figure 3-60. Adapter, quick fit, large frame.
Figure 3-61. Adapter, quick fit, reversible.
Figure 3-62. Adapter, 2 piece.
Figure 3-63. Adapter, quick fit.
Figure 3-64. Adapter, quick fit, lightweight.
Figure 3-65. Adapter, quick fit, 1".
Figure 3-66. Adapter, quick fit release.
Figure 3-67. Link, removable connector.
Figure 3-68. Link, removable connector, speed.
Figure 3-69. Link, Rapide®.
Figure 3-70. Release, parachute canopy quick disconnect, Capewell.
Plastics and Synthetics
The term “plastic” used here is a generic term for synthetic materials. The use of these materials is primarily for stiffeners in containers. They replace the metal stiffeners used in military systems. High-density polyethylene (HDPE) was the first material used followed by Lexan®. Time has proven that moly disulfide (MDS) filled nylon is superior to the other materials and has become the most commonly used stiffener material. Today, the use of Lexan® is primarily in clear windows in pin protector flaps. Stiffeners should have rounded edges to prevent wear points and to minimize the ability of lines to half hitch around them. [Figures 3-80 through 3-84]
Figure 3-71. Ring, harness, 3-ring.
Figure 3-72. Ring, riser, middle, 3-ring.
Figure 3-73. Ring, riser, small, 3-ring.
Figure 3-74. Ring, riser, mini, 3-ring.
Fasteners
Fasteners are various types of devices designed to hold parts or components together or allow them to be held open or closed. The most common designs are hook and loop fasteners (Velcro®), snaps, grommets, and slide fasteners (zippers).
Figure 3-75. Ring, harness, tandem.
Figure 3-76. Ring, harness, replaceable, 3-ring.
Figure 3-77. Ring, harness, “O” 2058 Cadmium Ring.
Figure 3-78. Ring, harness, 5010-SS Ring.
Of all these, Velcro® and grommets play a major part in parachute manufacture. The use of Velcro® is primarily for protector flap closure designs, while grommets are for use in pack closing systems. Both fasteners are subject to extreme wear and tear in their normal use. Consequently, routine maintenance involves the repair and replacement of these items. [Figures 3-85 through 3-89]
Figure 3-79. Ring, harness, mini.
Figure 3-80. Ring, quick fit.
Housings
Housings are spiral-wound flexible tubing. Almost all are stainless steel. Their design is to route, house, and protect the ripcord cable. They are anchored to the container at one end and the ripcord pocket or mount at the other end. Most ripcord housings are compressible only, but some military housings used with seat parachutes are expandable as well. The reason that ripcord housings are compressible and nonexpandable is to prevent premature loading of the cable and pin as the rig is donned and the user moves around. One-pin sport container systems generally use a .26" inside diameter housing. Two-pin and most military containers use a .375" inside diameter housing. Ripcord housings are measured under slight tension.
Figure 3-81. Snap shackle.
Figure 3-82. Snap, static line, old style.
Figure 3-83. Snap, static line, new style.
Figure 3-84. Soft link.
The 3-ring release system employs the smaller .20" or .18" housing for use with Lolon (yellow), or Teflon (orange or red), coated release cables. These “cutaway” housings must be expandable and non-compressible. The reason for this is, in the case where the loop load is excessive, the non-compressible housing will resist the loop or “push” against it allowing an effective “pull” of the cable from the loop.
Figure 3-85. Molydisulfide Nylon—MDS (Nylatron®).
Figure 3-86. Poylethylene, high density (HDPE).
Thus the term “push-pull system.” A compressible housing compresses until it reaches its limit of compression, which could be as much as 20 percent of the total length. In a two-cable scenario, such as the 3-ring, the differential could be as much as to allow the short side to release without releasing the long side. Cutaway housings should be measured in a relaxed state and then compressed to ensure that it remains within the manufacturer’s allowable tolerance. [Figures 3-90A through 3-92C]
Figure 3-87. HDPE tubing, 1 ½".
Figure 3-88. Polycarbonate—Lexan®.
Ripcords, Cables, and Swages
The standard ripcord used today on most parachute systems consists of a stainless steel handle, 3⁄32" 7 × 7 corrosion resistant steel cable, a stainless steel terminal ball, and one or more stainless steel pins swaged onto the cable. The handles come in various shapes and sizes in order to be compatible with main lift web lengths and pocket sizes and particulars, such as whether the ripcord grip is inboard or outboard. The terminal ball may be of several configurations, such as a ball and shank design. The pins usually are one of two basic designs: intermediate pin or terminal pin. The advantage of the intermediate pin is that it can be visually inspected easily by the rigger in the field. The end of the 7 × 7 cable can actually be seen where it is ground off at the bend in the shank of the pin. Metal ripcord assemblies are used on reserve and emergency parachute systems and military mains. Main ripcords may also consist of plastic handles and nylon coated cable without pins.
Figure 3-89. Vinyl.
Figure 3-90. Fastener tape, hook and pile, nylon (Velcro®).
Figure 3-91. DOT Fasteners, Durable.
Figure 3-92. DOT Fasteners, Pull-the-dot.
On modern sport parachutes, the hand deploy pilot chute replaced the conventional ripcord, by either throwout or pull-out. These configurations use the curved or straight locking pins attached to the pilot chute bridle. [Figures 3-93 through 3-101]
Figure 3-93. Grommets.
Figure 3-94. Interlocking slide fasteners (zippers).
Miscellaneous
The miscellaneous category includes remaining items that do not fit in any of the other categories. They fall somewhat under the category of hardware, but are not load-bearing type hardware like legstrap friction adaptors or hip rings. Most of the these items are made of stamped metal rather than forged steel. The plastic-looking, nylon “SR-Type Snaps” are used on gear bags, helmets, and as temporary holds for things such as tandem passenger drogue release handles. [Figures 3-102 through 3-118]
Figure 3-95. Housing, flexible, ripcord.
Figure 3-96. Housing, flexible, ripcord.
Chapter Summary
Material identification and understanding of its functional application is one of the most important aspects of becoming a parachute rigger. In order to properly inspect and recertify equipment—which is the rigger’s primary task—one has to be able to recognize when a material is worn beyond its required strength or if the wrong material has been selected to make a repair.
Figure 3-97. Housing, flexible, 3-ring.
Figure 3-98. Handle, steel, ripcord.
New high-tech fabrics are continually being explored, especially in the area of canopy connector lines and canopy cloth. Great improvements have been made in the reduction of permeability of canopy fabrics. Permeability is a measure of the ease with which a fluid (air in this case) can move through the fabric. Various forms of silicone and polyurethane coatings are used to create what we call in the vernacular, “Zero-P.” Generally, coated canopy cloth is referred to as 0 cfm (cubic foot per minute), and uncoated canopy cloth is referred to as 0-3 cfm. When we speak of porosity, we are referring to a measure of the tiny open spaces in the weave of the fabric. As canopy fabric wears, it becomes more porous and the permeability increases.
Figure 3-99. A. Pin, ripcord, terminal; B. Pin, ripcord, intermediate.
Figure 3-100. A. Ball, terminal; B. Ball and shank.
Figure 3-101. 7×7 stainless steel corrosion resistant cable.
Figure 3-102A. Static line cable.
Figure 3-102B. Black pinless r/c cable.
Figure 3-102C. Lolon 3-ring cable.
Figure 3-103. Teflon 3-ring cable.
Figure 3-104. Nicopress swage, ³⁄32" and ³⁄16".
Figure 3-105. A. Release pin, curved; B. Release pin, straight.
Figure 3-106. Cones.
Figure 3-107. A. Eyes; B. Hooks.
Figure 3-108. End tabs.
Figure 3-109. Disc assembly, pilot chute ejector.
Figure 3-110. Rubber bands, parachute suspension line.
Figure 3-111. Clamp, housing, single.
Figure 3-112. Clamp, housing, double.
Figure 3-113. Stiffener, housing, Navy.
Figure 3-114. Stiffener, housing, Air Force.
Figure 3-115. Cylindrical spring, pilot chute.
Figure 3-116. MA-1 Spring, pilot chute.
Figure 3-117. Washers, locking, loop.
Figure 3-118. Nylon hardware.