1、NASM 7839-1998 Screws, Structural, Aircraft_ADOPTION NOTICE “7839, “SCREWS, STRUCTURAL, AIRCRAFTtr, was adopted on 1 DECEMBER 1999 for use by the Department of Defense (DoD). Proposed changes by DoD Activities must be submitted to the DoD Adopting Activity: Defense Supply Center Philadelphia, ATTN:
2、DSCP-ILEA, 700 Robbins Avenue, Philadelphia, PA 19111- 5096. DoD Activities may obtain copies of this standard from the Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094. The private sector and other Government agencies may purchase copies from the AER
3、OSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC., 1250 EYE STREET, N. W., WASHINGTON, DC 20005-3924. Custodians: Army - AV Navy - AS Air Force - 99 DLA- I S Adopting activity: DL&-IS (Project 5305-2438) AMSC N/A FSC 5305 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited.
4、 Copyright Aerospace Industries Association of America Inc. Provided by IHS under license with AIA/NASNot for ResaleNo reproduction or networking permitted without license from IHS-,-/:#:#$#:$*:$#:#NATIONAL AEROSPACE STANDARD Q COPYRIGHT 1998 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, MC. ALL RIGH
5、TS RESERVED NASM7839 SPECIFICATION SCREWS, STRUCTURAL, AIRCRAFT 1. SCOPE 1 .I Scope. This specification covers aircraft structural screws. 1.2 Classification. Screws shall be of the types and sizes designated by the part numbers on the military standard (MS) as specified (see 6.2). 2. APPLICABLE DOC
6、UMENTS 2.1 Government documents. 2.1 .I Specifications and standards. Unless othetwise specified (see 6.2). the following specifications and standards of the issue listed in that issue of the Department of Defense Index of Specifications and Standards (DoDISS) specified in the solicitation, form a p
7、art of this specification to the extent specified herein. SPECIFICATIONS Federal QQ-A-22516 QQ-A430 QQ-B-728 QQ-P-35 QQ-P416 QQ-S-763 PPP-H-1581 Aluminum Alloy Bar, Rod, And Wire; Rolled, Drawn, or Cold Finished, 2024 Aluminum Alloy Rod And Wire; For Rivets And Cold Heading Bronze Manganese; Rod, Sh
8、apes, Forgings, And Flat Products (Flat Wire, Strip, Sheet, Bar, And Plate) Passivation Treatments For Corrosion- Resisting Steel Plating, Cadmium (Electrodeposited) Steel Bars, Wire, Shapes, And Forgings, Corrosion-Resisting Hardware (Fasteners And Related Items), Packaging and Packing For Shipment
9、 And Storage of THE INITIAL RELEASE OF THIS DOCUMENT SUPERSEDES MIL-S-7839, REVISION B, AMENDMENT 3. LIST OF CURRENT SHEETS NO. NEW 9 NEW 3 NEW 8 NEW 2 NEW 7 NEW 1 REV. NO. REV. L 4 NEW 10 6 NEW Il NEW 5 NEW NEW . . . . . SHEET 1 of 11 FSC 5305 APPROVAL DATE DECEMBER 1998 REVISION USE OF OR RELIANCE
10、 UPON THIS DOCUMENT OR ANY NATIONAL AEROSPACE STANDARD IS ENTIRELY VOLUNTARY. AIA DOES NOT QUALIFY SUPPLIERS OR CERTIFY CONFORMANCE OF ITEMS PRODUCED UNDER NATIONAL AEROSPACE STANDARDS. AIA MAKES NO REPRESENTATION OR CLAIM RESPECTING (1) THE SUITABILITY OF ITEMS FOR ANY PARTICULAR APPLICATION, OR (2
11、) THE EXISTENCE OF OR APPLICABILITY THERETO OF PATENT OR TRADEMARK RIGHTS Copyright Aerospace Industries Association of America Inc. Provided by IHS under license with AIA/NASNot for ResaleNo reproduction or networking permitted without license from IHS-,-/:#:#$#:$*:$#:#STD.AIA/NAS NASM7839-ENGL L99
12、8 03L87Li3 050bZLb 972 = NATIONAL AEROSPACE STANDARD O COWRIGHT 1998 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. ALL RIGHTS RESERVED NASM7839 Military MIL-Sb049 MIL-Sa050 MIL-H-6088 MIL-S-6098 MILS-6758 MIL-1-6866 MIL-1-6868 MIL-H-6875 MIL-S-7742 MIL-A-8625 MIL-S-8879 MIL-18732 STANDARDS Milit
13、ary MIL-STD-105 MIL-STD-410 MIL-STD-1312 MS9006 MS24694 MS27039 MS33750 MS14191 MS33781 Air Force - Navy Aeronautical AN502 AN503 AN525 Steel, Chrome-Nickel-Molybdenum (8740) Bars And Reforging Stock (Aircraft Quality) Steel, Chrome-Nickel-Molybdenum (8630) Bars And Reforging Stock (Aircraft Quality
14、) Heat Treatment of Aluminum Alloys Steel, Chrome Nickel-Molybdenum (8735) Bars And Reforging Stock (Aircraft Quality) Steel, Chrome-Molybdenum (4130) Bars And Reforging Stock (Aircraft Quality) Inspection, Penetrant Method Of Inspection Process, Magnetic Particle Heat Treatment Of Steels (Aircraft
15、Practice) Process For Screw Threads, Standard, Optimum Selected Series: General Specification For Anodic Coatings, For Aluminum And Aluminum Alloys Screw Threads, Controlled Radius Root With Increased Minor Diameter; General Specification For Steel Bars, Billets, Forgings, Tubing (431). Special Qual
16、ity Sampling Procedures And Tables For Inspection By Attributes Non-Destructive Testing Personnel Qualification and Certification (Eddy Current, Liquid Penetrant, Magnetic Particle, Radiographic and Ultrasonic) Fasteners, Test Methods Recesses-Cross, Low Torque Drive, Dimensions And Gage Dimensions
17、For Screw, Machine, Flat Countersunk Head, looo, Structural, Cross Recessed, UNC3A And UNF-SA Screw, Machine - Pan Head, Structural, Cross Recessed Recess-Hi-Torque, Dimensions of Recess, Gage, and Driver For Recess, Ribbed Torque-Set, Dimensions of Recess, Gage and Driver For Recess, Torq-Set, Dime
18、nsions of Recess, Gage and Driver For Screw - Machine, Drilled Fillister Head, Fine Thread Screw-Machine, Drilled Fillister Head, Coarse Thread Screw -Washer Head (Copies of specifications and standards required by manufacturers in connection with specific acquisition functions should be obtained fr
19、om the contracting activity or as directed by the contracting officer.) 2.2 Other publications. The following document(s) form a part of this specification to the extent specified herein. The issues of the documents which are indicated as DoD adopted shall be the issue listed in the current DoDlSS a
20、nd the supplement thereto, if applicable. SOCIETY OF AUTOMOTIVE ENGINEERS, INC. AMS 6300 -Steel, .25 MO (.35-.4OC) (Applications for copies should be addressed to the Society of Automotive Engineers, Inc., 485 Lexington Avenue, New York, NY 10017.) 2 APPROVAL DATE DECEMBER 1998 REVISION USE OF OR RE
21、LIANCE UPON THIS DOCUMENT OR ANY NATIONAL AEROSPACE STANDARD IS ENTIRELY VOLUNTARY. AIA DOES NOT QUALIFY SUPPLIERS OR CERTIFY CONFORMANCE OF ITEMS PRODUCED UNDER NATIONAL AEROSPACE STANDARDS. AIA MAKES NO REPRESENTATION OR CLAIM RESPECTING (1) THE SUITABILITY OF ITEMS FOR ANY PARTICULAR APPLICATION,
22、 OR (2) THE EXISTENCE OF OR APPLICABILITY THERETO OF PATENT OR TRADEMARK RIGHTS Copyright Aerospace Industries Association of America Inc. Provided by IHS under license with AIA/NASNot for ResaleNo reproduction or networking permitted without license from IHS-,-/:#:#$#:$*:$#:#NATIONAL AEROSPACE STAN
23、DARD O COPYRIGHT 1998 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. ALL RIGHTS RESERVED NASM7839 2.3 Order of precedence. In the event of a conflict between the text of this specification and the references cited herein, the text of this specification shall take precedence. 3. REQUIREMENTS 3.1 D
24、ata. Unless otherwise specified in the contract or order, no data are required by this specification or any of the documents referenced in Section 2 (see 6.2). 3.2 Material. 3.2.1 Low-alloy steel. Low-alloy steel screws having .4375 inch body diameter and less shall be manufactured from steel confor
25、ming to AMS 6300 or MIL-S-6050. Low-alloy steel screws having a body diameter greater than ,4375 inch shall be manufactured from steel conforming to MIL-S-6049, MIL-S-6050, MIL-S-6098, MIL-S-6758, or AMS6300. 3.2.2 Corrosion-resistant steel. Corrosion-resistant steel screws shall be manufactured fro
26、m material conforming to QQ-S- 763, class I. type C; QQ-S-763, class IV; or MIL-S-18732, or equal, or interchangeable with 16-18 chrome-nickel alloy steels. 3.2.3 Aluminum alloy. Aluminum-alloy screws shall be manufactured from material conforming to QQ-A-430, alloy 2024, or QQ-A-22516 in the soluti
27、on heat-treated T4 temper. 3.2.4 Manganese bronze. Manganese bronze screws shall be manufactured from material conforming to QQ-B-728. 3.3 Design and construction. 3.3.1 Threads. Threads of all screws shall conform to MIL-S-7742 or MIL-S-8879, as specified, and shall be of the sizes specified on the
28、 applicable MS. Unless otherwise specified, threads shall be right hand. 3.3.1 .I m. The grip length shall be measured from the largest diameter of the bearing surface of the head, parallel with the screw axis. to the end of the unthreaded shank. 3.3.2 Head eccentricity. Machine screw heads shall no
29、t be eccentric with the screw bodies by more than 3 percent of the maximum head diameter. Eccentricity is defined as one-half of the total indicator reading (TIR). 3.3.2.1 Bearing surface. The bearing surface of protruding screw heads shall be at right angles to the body within 2 degrees. 3.3.2.2 Sl
30、ot drive. When a screw with a slot drive is required, the dimensions of the slot shall be as shown on the applicable screw standard. 3.3.2.3 Recess drive. Recess dimensions shall conform to MS9006, MS14191, MS33750 or MS33781 as specified on applicable standard or drawing. 3.3.3 Straightness of shan
31、k. The straightness of the shank shall be within the values specified in Table I when the screw is rolled on a surface plate and the point of greatest deviation is measured with a feeler gage of .250 inch width. The straightness of shank requirements shall apply to size .I90 and larger screws, and s
32、crews smaller than size .I90 that have a length greater than six times their diameter. For screws under size .190, the straightness of shank from Table I for size ,190 shall be used. APPROVAL DATE DECEMBER 1998 REVISION USE OF OR RELIANCE UPON THIS DOCUMENT OR ANY NATIONAL AEROSPACE STANDARD IS ENTI
33、RELY VOLUNTARY. AIA DOES NOT QUALIFY SUPPLIERS OR CERTIFY CONFORMANCE OF ITEMS PRODUCED UNDER NATIONAL AEROSPACE STANDARDS. AU MAKES NO REPRESENTATION OR CLAIM RESPECTING (1) THE SUITABILITY OF ITEMS FOR ANY PARTICULAR APPLICATION, OR (2) THE EXISTENCE OF OR APPLICABILITY THERETO OF PATENT OR TRADEM
34、ARK RIGHTS Copyright Aerospace Industries Association of America Inc. Provided by IHS under license with AIA/NASNot for ResaleNo reproduction or networking permitted without license from IHS-,-/:#:#$#:$*:$#:#STD.AIA/NAS NASM7837-ENGL 1778 0338743 05Ob218 745 NATIONAL AEROSPACE STANDARD O COPYRIGHT 1
35、998 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. ALL RIGHTS RESERVED NASM7839 TABLE 1. Straightness of Shank I I Deviation of screw shank from plate, maximum (inch Screw Size per inch of screw length) .i90 ,250, .3125 .375, .4375 500 and larger 0.0040 ,0030 .O025 ,0020 3.4 Heat treatment. 3.4.1
36、 9. Low-alloy steel screws shall be heat treated in accordance with MIL-H-6875. 3.4.2 Aluminum alloy. Aluminum-alloy screws manufactured from material conforming to QQ-A-430. alloy 2024, shall be heat treated in accordance with MIL-H-6088. 3.5 Physical properties. 3.5.1 Tensile strength. The tensile
37、 strength of the screws shall be as specified in Table II, when tested in accordance with 4.4. 3.5.2 Hardness. All low-alloy steel screws shall be within the Rockwell hardness range C-26 to C-32, when tested in accordance with 4.5. 3.5.3 Cracks. Screws shall be free of cracks in any direction and lo
38、cation. A crack is defined as a clean crystalline break passing through the grain or grain boundary without the inclusion of foreign elements. 3.5.4 Discontinuities. All structural screws shall be acceptable, provided they do not contain discontinuities which equal or exceed the following limitation
39、s. Care must be taken not to confuse cracks (see 3.5.3) with discontinuities. 4 APPROVAL DATE DECEMBER 1998 REVISION USE OF OR RELIANCE UPON THIS DOCUMENT OR ANY NATIONAL AEROSPACE STANDARD IS ENTIRELY VOLUNTARY. AIA DOES NOT QUALIFY SUPPLIERS OR CERTIFY CONFORMANCE OF ITEMS PRODUCED UNDER NATIONAL
40、AEROSPACE STANDARDS. AIA MAKES NO REPRESENTATION OR CLAIM RESPECTMG (1) THE SUITABILITY OF ITEMS FOR ANY PARTICULAR APPLICATION, OR (2) THE EXISTENCE OF OR APPLICABILITY THERETO OF PATENT OR TRADEMARK RIGHTS Copyright Aerospace Industries Association of America Inc. Provided by IHS under license wit
41、h AIA/NASNot for ResaleNo reproduction or networking permitted without license from IHS-,-/:#:#$#:$*:$#:#STD.AIA/NAS NASM7A34-ENGL 1778 03116743 05flb217 bB1 NATIONAL AEROSPACE STANDARD Q COPYRIGHT 1998 AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. ALL RIGHTS RESERVED NASM7839 TABLE II. Strength
42、 Requirements Ultimate tensile strength strength (minimum)2 pounds (minimum)i pounds Ultimate double shear Corrosion: Corrosion- Low-alloy alloy steel Steel alloy steel Steel Aluminum resistant Low-alloy Aluminum resistant Size Coarse Thread ,138-32UNC-3 5.700 7,820 11,500 3.230 4,440 6,520 3,650 .3
43、125-18UNC-3 2,092 5,000 7,360 1,960 2,700 3.960 ,250-20UNC-3 1,570 2,770 4,250 1 ,O 80 I ,480 2.1 70 ,190-24UNC-3 1,080 2,100 3.000 a60 1 ,I 80 1,740 ,164-32UNC-3 1,480 2.1 20 560 760 1,120 Fine Thread .13840UNF-3 .19032UNF-3 2,l O0 3,000 900 I ,240 1,820 ,164-36UNF-3 1,080 1.480 2,120 630 860 1,260
44、 1,570 2,490 1,690 1,230 4,250 3,650 5,000 7,360 2,240 3,080 4,520 .250-28UNF-3 2,092 2,770 ,3125-24UNF-3 7,240 4,920 3,590 11,500 7.820 ,375-24UNF-3 5,700 10,950 7,450 5,430 16,560 11,250 8,250 ,4375-20UNF-3 14,800 I 0,070 7,350 22,500 .5000-20UNF-3 15,300 1 1,200 19,950 13,570 9,900 29,400 20,000
45、14,600 ,5625-18UNF-3 25,300 17,200 12,560 37,400 25,300 18,500 The values shown for the ultimate tensile strength are for minimum values and are based on: 125 KSI for low-alloy steel. 85 KSI for corrosion-resistant steel. 62 KSI for aluminum alloy. The stress areas used for the calculation of the te
46、nsile strength values are based on the average of the mean pitch and minor diameters of the external thread. Ultimate shear strengths are computed on the basis of 60 percent of the ultimate tensile strengths. 3.5.4.1 Longitudinal discontinuities. Longitudinal discontinuities extending through fillets or threads as shown on Figure 1 that exceed the limits shown in Table 111 shall not be acceptable.
