1、 Beneficial comments (recommendations, additions, deletions) and any pertinent data that may be of use in improving this document should be addressed to: Natick Soldier Center ATTN: AMSSB - RAD - AD(N), Natick, MA 01760 - 5017, using the Standardization Document Improvement Proposal (DD Form 1426) a
2、ppearing at the end of this document or by letter. AMSC N/A FSC 1670 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. INCH - POUND MIL - DTL - 7620D 30 October 2002 SUPERSEDING MIL - P - 7620C 7 October 1982 DETAIL SPECIFICATION PARACHUTES AND COMPONENTS, CARGO, EXTR
3、ACTION AND DECELERATION, GENERAL SPECIFICATION FOR This specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope . This Specification cover cargo, extraction and deceleration parachute assemblies and components. 1.2 Classification . The class
4、ification of parachute assemblies are defined as part numbers (See 6.2). 2. APPLICABLE DOCUMENTS 2.1 General . The documents listed in this section are cited in sections 3 and 4 of this specification. These lists do not include documents cited in other sections of this specification or recommended f
5、or additional information or as examples. While every effort has been made to ensure the completeness of these lists, document users are cautioned that they must meet all specified requirements documents cited in sections 3 and 4 or this specification, whether or not they are listed. 2.2 Government
6、documents . 2.2.1 Specifications and Standards . The following specifications and standards form a part of this document to the extent herein. Unless otherwise specified, the issues of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (D
7、oDISS) and supplement thereto, cited in the solicitation (see 6.2). Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL - DTL - 7620D 2 SPECIFICATIONS FEDERAL A - A - 59291 - Ink, Marking (For Parachutes and other Textile Items) STANDARDS DE PARTMENT
8、 OF DEFENSE MIL - STD - 849 - Inspection Requirements, Definitions and Classification of Defects in Parachutes 2.3 Non - government publications . The following documents form a part of this document to the extent specified herein. Unless otherwise specified, the issues of the documents that are DoD
9、 adopted are those listed in the issue of the DoDISS cited in the solicitation. Unless otherwise specified, the issues of documents not listed in the DoDISS are the issues of the documents cited in the s olicitation. AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM) ASTM D 6193 - Standard Practice f
10、or Stitches and Seams ASTM D 737 - Test Methods for Air Permeability of Textile Fabrics. (Application for copies should be addressed to the American Socie ty for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428 - 2959.) 2.4 Order of precedence . In the event of a conflict be
11、tween the text of this document and the references cited herein (except for related associated specifications o r specification sheets), the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption has been obta
12、ined. 3. REQUIREMENTS 3.1 First article . When specified (see 6 .2), a sample shall be subjected to first article inspection in accordance with 4.2. 3.2 Materials . Materials shall conform to the requirements of the applicable TDP, to subsidiary specifications and standards applicable thereto, and a
13、s specified herein . 3.2.1 Recycled, recovered, or environmentally preferable materials. Recycled, recovered, or environmentally preferable materials should be used to the maximum extent possible provided Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,
14、-,-MIL - DTL - 7620D 3 the material meets or exceeds the operational requirements, and pro motes economically advantageous to life cycle costs. 3.3 Construction. Details of construction shall be in accordance with manufacturing specifications supplied by the procuring activity, the TDP for the assoc
15、iated item and the additional requirements s pecified herein. 3.3.1 Assembly aids. Drilling, notches, stapling, basting or any other such techniques used as aids in the manufacturing process of parachutes shall be kept to a minimum, and the use thereof shall be restricted to the same limitations a s
16、 marking (see 3.3.1.2). All assembly aids, such as staples, shall be removed during or after assembly. 3.3.1.1 Basting. Basting requirements shall be as specified in the TDP or be in accordance with common industry practices. Basting stitches shall n ot be seen in the finished seam or assembly. Cont
17、ractors unfamiliar with commercial practices shall contact the contracting officer for specific details prior to assembly of the item. 3.3.1.2 Assembly markings. Markings on the canopy, riser, and other components as an aid to assembly and to indicate stitching patterns shall be accomplished in a ma
18、nner that will not adversely affect the utility, strength, or appearance of the parachute. 3.3.2 Measuring and cutting of textiles. Unless otherwise specifi ed on the applicable drawings, all textile materials shall be measured and cut while substantially free of any tension. Tightly would textile m
19、aterials shall be unrolled and allowed to relax before they are measured or cut. Webbings and tapes shall be re laxed for not less than 24 hours. Devices used for measuring textile materials shall not induce false or uneven loads on the materials. If materials are measured and cut under tension, a s
20、tandard time for load application, marking, and cutting shall be e stablished and maintained. When multiple layers of textile materials are cut at one time, care shall be taken to prevent the material from slipping during the cutting operation. Where large changes in temperature and humidity occur,
21、care shall be taken t o minimize the effect of these changes on the measurements of materials. When patterns are specified on drawings, they shall be used as specified. Pattern dimensions and details shall not be changed. 3.3.3 Coreless nylon cord. The carrier ends of core less nylon cord may be spl
22、iced during the manufacture of the cord. 3.3.3.1 Cargo parachute assemblies. The carrier ends of coreless nylon cord for cargo parachute assemblies shall be trimmed flush. 3.3.3.2 Extraction and deceleration parachute assembl ies. The finished length of the carrier ends of coreless nylon cord for ex
23、traction and deceleration parachute assemblies shall not be more than 1 inch. Carrier ends not exceeding 1 inch shall be left exposed and uncut. Carrier ends exceeding 1 inch in l ength shall be trimmed to a maximum finished length of 1 inch. 3.3.4 Trimming of canopy gores. Where trimming of the can
24、opy gores is required to conform to construction requirements, the trimming shall be as specified in 3.3.4.1 and 3.3.4.2. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL - DTL - 7620D 4 3.3.4.1 S ide of gore at cross seam. Trimming from the side
25、of the gore at the cross seam shall not be more than inch and shall be a tapering cut to avoid abrupt changes in the width of the gore. The adjacent section of the mating gore shall not be trimmed. 3.3 .4.2 Lower edge of gore at main seam. A maximum of 3 inches may be trimmed from the lower edge of
26、one gore at each main seam of canopies that are over 35 feet in diameter. A maximum of 1 - 1/2 inches may be trimmed from the lower edge of one gore at each main seam of canopies that are under 35 feet in diameter. The trimming shall be a long tapering out. 3.3.5 Stitches and stitching. 3.3.5.1 Mach
27、ine stitching. All machine stitching shall conform to ASTM - D - 6193 and shall be the type specified on the ap plicable drawings. Stitches shall be smooth without looping. The thread tension shall not cause the cloth under the seam to pucker or result in the thread breaking when the seam is placed
28、under tension. Multiple - needle machines shall be adjusted to prov ide uniform tension for each needle insofar as practicable. 3.3.5.2 Automatic machinery stitching. Stitching patterns produced by automatic machines may be utilized in lieu of those specified, providing the basic design and size of
29、the pattern, the size of the thread, and number of stitches per inch are as specified on the drawing. A minimum of three tie - in, overlapping, or back stitches shall be used to secure the ends. 3.3.5.3 Thread breaks during sewing. If the thread breaks in either stitch type 304 or 308 during sewing,
30、 the end of the break shall be overlapped a minimum of three stitches and the sewing shall then be resumed. If the thread breaks in stitch type 301 during sewing, the end of the break shall be overlapped a minimum of 1 inch and th e sewing shall then be resumed. 3.3.6 Searing and dipping. Unless oth
31、erwise specified on the drawings, no searing shall be done after stitching. Searing shall not result in sharp edges or points. During the dipping operation, the temperature of the pa raffin and beeswax mixture shall be maintained at 180 degrees (plus or minus 20 degrees) Fahrenheit. 3.3.7 Stitching
32、repairs. 3.3.7.1 Loose stitches. Loose stitches shall not be removed but shall be reinforced by adjacent stitching. 3.3.7.2 Tight st itches. Tight stitches shall be removed, and the section shall be restitched. 3.3.7.3 Broken or skipped stitches. Broken or skipped stitches in stitch type 301 shall b
33、e repaired by adjacent stitching with the stitches extending a minimum of 1 inch beyo nd the ends of the stitches being repaired. Broken or skipped stitches in stitch type 304 or 308 shall be repaired by adjacent stitching with the stitches extending a minimum of three stitches beyond the ends of th
34、e stitches being repaired. Broken or ski pped stitches in stitch type 401 shall be repaired with stitch type 301 and as specified for broken or skipped stitches in stitch type 301. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL - DTL - 7620D 5 3
35、.3.7.4 Run - offs. A run - off shall be repaired by stitching within the seam margin tolerance with the stitches ext ending a minimum of 1 inch or three stitches, as applicable to the type of stitch, from the start and the end of the run - off. 3.3.7.5 Less than specified number of stitches per inch
36、. Where the number of stitches per inch is less than the specified numbe r, repairs shall be made by adjacent stitching, with the repair extending either 1 inch or three stitches, as applicable to the type of stitch, beyond the end of the repair. 3.3.8 Darning of canopy. Darning of the canopy shall
37、be held to a minimum. Hol es and linear cuts or tears not exceeding the limitations specified in MIL - STD - 849 may be darned without authorization from the procuring activity. The darned area for holes may be either round or square and shall cover a 3/8 - inch area beyond the hole on all sides. Th
38、e darned area of linear tears or cuts shall be rectangular and shall cover a - inch area beyond the sides and the ends of the tear or cut. Size A nylon thread or yarns from canopy cloth shall be used for darning. The color of the thread sha ll match the color of the canopy cloth upon which it is use
39、d. 3.3.9 Repairs. The following repairs may be made without authorization from the procuring activity. 3.3.9.1 Repairs to vent and skirt hem pleats. Vent and skirt hem pleats in excess of the limitations specified in MIL - STD - 849 shall be repaired as follows: Remove the inside row of stitching th
40、en distribute the cloth of the pleat and restitch using the specified stitch type. 3.3.9.2 Patching of packs and bags. Parachute packs and deployme nt bags may be repaired by patching. Patching shall be neat and shall not exceed an area of 6 inches by 6 inches nor a length of 8 inches. No deployment
41、 bag or parachute pack shall contain more than one patch. 3.3.9.3 Patching of a canopy. A canopy ma y have one sewn patch not to exceed a damaged area size of 49 square inches. The patch shall not be located closer than 1 inch to a radial seam, edge reinforcement or lower lateral band. The patch sha
42、ll be square or rectangular in shape. A canopy having one patch shall be classified as a minor defect more than one patch a major defect. 3.3.9.3.1 Patching procedure. The patch shall be applied to the inside of the canopy as shown in Figure 1, and installed as follows: a. Place the repairable item
43、on a repair table, smooth the fabric around the damaged area, and secure the item to the table with pushpins. Do not pin the damaged area. b. Using an authorized marking aid of contrasting color, mark a square or rectangle around the area to be patched an d insure that one side of the marking square
44、 or rectangle is parallel to the warp or filling of the fabric. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL - DTL - 7620D 6 c. Cut the damaged area fabric along the lines made in (b) above. Further cut the fabric diagonally at each corner to
45、allow a inch fold back in the raw edges. d. Make a inch foldback on each raw edge. Pin and baste each foldback to complete the prepared hole. e. Using the same type material as in original construction, mark and cut a patch 2 - 1/2 inches wider and longer than the inside meas urements of the prepare
46、d hole. Insure that the patch material is marked and cut along the warp or filling of the fabric. f. Center the patch material over the prepared hole and insure the warp or filling of the patch material matches the warp or filling of the fabric being patched. Pin the patched material in position. g.
47、 Make a inch fold under on each edge of the patch material and baste the patch to the prepared area. h. Remove the pushpins securing the item to the repair table and secure the pa tch by machine stitching, using the applicable details in Figure 1. The stitching should be accomplished with thread tha
48、t is contrasting in color to the fabric. Thread shall be V - T - 295, size “E” Nylon, Type I, II or III, Class A, Type 301, using 7 to 11 stitches per inch in accordance with ASTM - D -6193. Back stitch inch minimum or lock by at least 2” minimum and not more than 4 inches at each end of a stitch ro
49、w. 3.4 Air permeability. When tested in accordance with 4.5, complete canopies shall have a n average permeability of not more than 10 percent over the top limit or 10 percent below the lower limit of the fabric specification. The average air permeability reading for any one gore shall not exceed the upper limit, nor be less than the lower limit of the fabric specification by over 20 percent. 3.5 Identification of product. 3.5.1 Component. Unl
