1、STD=AECMA PREN 3908-ENGL 1997 3032333 001b257 319 Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM C3 Chairman Comments should be sent within six months after the date of Dublication to prEN 3908 Edition P 2 May 1999 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES
2、 (AECMA) Gulledelle 94 - 6-1200 BRUXELLES - Tel. (+32) 2 775 81 10 - Fax. (+32) 2 775 81 11 ICs: 49.035 / 49.1 O0 Supersedes issue P 1 February 1994 Descriptors: Aircraft industry, lubricating system, grease fitting, corrosion resistant steel, specification, test, dimension, dimensional tolerance, s
3、urface treatment, designation, marking ENGLISH VERSION Aerospace series Nipples, lubricating, axial type, in corrosion resisting steel, passivated Srie arospatiale Luft- und Raumfahrt Graisseurs accrochage axial, Kegel-Schmiernippel, en acier rsistant la corrosion, passivs aus korrosionsbestndigem S
4、tahl, passiviert This Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Association of Aerospace Industries). It is published on green paper for the needs of AECMA-Members. It has been technically approved by the experts of the concerned Technical Commit
5、tee following comment by the Member countries. Subsequent to the publication of this Prestandard, the fechnical content shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. Affer examination and signature of the
6、 AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. Nota - Extra copies can be supplied by B.N.A.E. - Technopoiis 54 - 199, rue J
7、ean-Jacques Rousseau - 921 38 ISSY-LES-MOULINEAUX CEDEX 1999-05-31 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Visconti STDOAECMA PREN 3908-ENGL L999 LO123LL 00Lb258 255 = Page 3 prEN 3908: 1999 1 Scope This standard specifies the required characteristics and the tests for lubricating nipples of the axi
8、al type, in corrosion resisting steel, passivated. Annex A (normative) states the clearance space requirements for the coupling and uncoupling of the lubricating gun and the maximum permissible diameter of the lubricating gun barrel, together with installation thread requirements. Lubricating nipple
9、s according to this standard are intended for use in aerospace assemblies, where regular lubrication of moving parts is required. 2 Normative references IS0 68 IS0 general purpose screw threads - Basic profile IS0 413 Aircraft - Heads of lubricating nipples IS0 965-2 IS0 general purpose metric screw
10、 threads - Tolerances - Part 2: Limits of sizes for general purpose bolt and nut threads - Medium quality IS0 2859-1 Sampling procedures for inspection by attributes - Part 1 : Sampling plans indexed by acceptable quality level (AQL) for lot-by-lot inspection IS0 6507-1 Metallic materials - Hardness
11、 test - Vickers test - Part 1 : HV 5 to HV 1 O0 EN 2000 Aerospace series - Quality assurance - EN aerospace products - Approval of the Quality system of manufacturers EN 2424 Aerospace series - Marking of aerospace products EN 2516 Aerospace series - Passivation of corrosion resisting steels and dec
12、ontamination of nickel based alloys STANAG 1 135 - 1983 Interchangeability of fuels, lubricants and associated products used by the armed forces of the North Atlantic Treaty Nations 1) 3 Required characteristics 3.1 The envelope dimensions for the nipple head are shown in figure 1, detail ?Z? and ar
13、e in accordance with IS0 413. The tip design of the nipple (face with the sealing ball) is left at the manufacturer?s option provided the profile remains within the envelope dimensions shown in figure 1 and the requirements of clause 7 are met. Configuration - Dimensions - Masses The dimensions appl
14、y after surface treatment. A check valve (composed of a spring and ball) shall be located at the surface of the nipple to prevent the ingress of foreign matter into the nipple tip. Other internal design shall be at the manufacturer?s discretion provided the nipples meet the requirements specified in
15、 clause 7. 1) Published by : North Atlantic Treaty Organization (NATO), Military Agency for Standardization (MAS), 11 10 Brussels, Belgium previous page is blallk Page 4 prEN 3908: 1999 3.2 Surface roughness Ra = 6,3 pm unless otherwise specified. The values apply prior to surface treatment. The sur
16、face roughness of the thread will be as achieved by normal methods of manufacture. 3.3 Materials Austenitic chromium-nickel steel ; ultimate strength min. 550 MPa. See also 7.6.2. The nipple head surface shall be case hardened to a depth of 0,08 mm to 0,13 mm to give a minimum hardness value of HV53
17、3 (52 HRC). The nipple body shall withstand a tigthening torque of 9 Nm without strain. Material and surface treatment for the internal parts of the nipple shall be at the manufacturers option. 3.4 Surface treatment EN 2516, process appropriate to the material Page 5 prEN 3908: 1999 STD-AECMA PREN 3
18、908-ENGL 1999 W 1012311 00Lb2b0 903 Dimensions in millimetres Mass: max. 3g/piece Form A (code 01) Mass: max. 1 Ogpiece Form B (code 02) K3 + 595 max. Key 1 At manufacturers option 2 3 4 Across flats 5 Maximum contour (broken line) 6 Minimum contour (continuous line) a Shape optional Marking area (f
19、or forms A, B & C) Detail X: see figure 2, page 6. Mass: max. 1 1 gipiece Form C (code 03) Figure 1 R 0,108 - Figure 2 - Detail X of figure i 4 Designation EXAMPLE: Description block Identity block I NIPPLE STD=AECMA PREN 3908-ENGL 1999 Page 7 prEN 3908: 1999 6 Technical specification The lubricatin
20、g nipples shall meet the requirements of this standard. For quality assurance requirements, see EN 2000. 7 Requirements and test methods Acceptance tests shall be carried out for each inspection lot. Samples shall be selected from the inspection lots in accordance with the requirements of IS0 2859-1
21、. For non-destructive tests “General inspection level“ II and an AQL of 1 ,O for sample size (n) shall be used (see table 1). For destructive tests “Special level“ S4 and an AQL of 13 for sample size (n) shall be used (see table 2). NOTE: The requirements for “continuation of inspection“, “switching
22、 procedures“ and “discontinuation of inspection shall be in accordance with 9.2, 9.3 and 9,4 of IS0 2859-1. Table 1 Batch size (pieces) I 90 91 to 150 151 to 280 281 to 500 501 to 1200 1201 to 3200 3 201 to 10 O00 n 13 20 32 50 80 125 200 AC Table 2 501 to 10 O00 32 7.1 Materials and surface treatme
23、nt The manufacturer shall provide a test certificate proving that all materials and surface treatments comply with the requirements of 3.3 and 3.4 and shall also show that the quality has been maintained throughout all stages of nipple manufacture. 7.2 Dimensions Components shall be inspected to ver
24、ify that they conform to the relevant requirements of 3.1. Sample size: see table 1. The thread test and the verification of the absence of burrs are not included (see 7.3 or 7.6.1). 7.3 Absence of burrs The nipple shall be submitted to a 100 % inspection to check the absence of burrs. 7.4 Marking M
25、arking shall comply with the requirements of clause 5. Sample size: see table 1. Page 8 prEN 3908: 1999 STD-AECIA PREN 3908-ENGL 1979 1012311 001h263 b12 7.5 Hardness 7.5.1 of the lubricating nipple. Sample size: see table 2. The hardness test (Vickers) in accordance with IS0 6507-1 shall be carried
26、 out on the across flats 7.5.2 A minimum of five components shall be selected from those tested according to clause 7.5.1 7.5.3 They shall be fractured and the case depth shall be as specified in clause 3.3. 7.6 For the purpose of these tests a parallel internal thread M6x1-6H shall be cut into a st
27、eel plate (strength 2 900 MPa). There shall be no chamfer at the entrance of the thread. Thread inspection and strength test 7.6.1 Thread test The thread shall be submitted to a 100 % inspection. It shall be possible to engage each nipple manually as deep as indicated in figure 3. Dimensions in mill
28、imetres 1 to 2 t Key I Test plate, see 7.6. Figure 3 7.6.2 Strength test The lubricating nipples shall withstand the tightening torque requested in 3.3 when installed in a test plate to the requirements of 7.6. When removed there shall be no sign of strain on the nipple body and there shall be no su
29、bstantial change in the tapered nipple thread. Sample size: see table I. 7.7 Performance check Admit lubricant at a pressure of 7 MPa with the coupled gun held at an angle of 10“ to the nipple axis. 7.7.1 out on each assembled nipple to ensure that the check valve will open and seat satisfactorily.
30、A production check, of a simple mechanical nature not involving the use of grease, shall be carried No lubricant leakage is permitted between the gun and the nipple head. 7.7.2 Ten nipples of each form, shall be shown to meet the design performance requirements laid down in table 3 using a lubricant
31、 complying with NATO G-354 (see STANAG 1135). The test block shall have a minimum capacity of 10 ml (a suitable form of test block is depicted in figure 4). Table 3 I Test I Requirements and limitations I I Opening of the nipple valve I Between 1 MPa and 3,5 MPa I I Leakage at sustained pressure of
32、35 MPa I 2 ml / min max. 2 I Key 1 2 Vent-screw Minimum capacity of grease duct: 10 rnl Figure 4 - Test block Page 10 prEN 3908: 1999 STDoAECMA PREN 3908-ENGL 1999 LOL23LL UOLb265 495 Annex A (normative) Installation requirements A.1 Space requirements Sufficient clearance space shall be provided ar
33、ound the lubricating nipple to allow the coupling and uncoupling of the lubricating gun as shown in figure A.1. It shall be noted that, in uncoupling, the gun has to be tilted up to 25“ in any radial direction. Dimensions in millimetres Key 1 Uncoupling angle Figure A.1 A.2 Installation thread requirement The installation hole shall have a parallel thread conforming to M6x1-6H to the requirements of IS0 68 and IS0 965-2.
