1、AECMA STANDARD prEN 4251 NORME AECMA Edition P 1 AECMA NORM Janup 1997 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE INDUSTRIES (AECMA) Gulledelle 94 - B-1200 BRUXELLES - Tel. (32) 2 775 81 1 O - Fax. (32) 2 775 81 1 1 I ICs : 49.040.20 ENGLISH VERSION Aerospace series Nuts, anchor, self-lockin
2、g, fixed, 90 corner, with counterbore, in heat resisting steel, silver plated Classification : 1 100 MPa (at ambient temperature) / 425 OC Srie arospatiale crous river, freinage interne, fixes, dangle 90, avec chambrage, en acier rsistant chaud, argents Classification : 1 100 MPa ( temprature ambian
3、te) I425 OC Luft- und Raumfahrt Annietmuttern, selbstsichernd, 90 Eckflansch, mit zylindrischer Aussenkung, aus hochwarmfestem Stahl, versilbert Klasse : 1 100 MPa (bei Raumtemperatur) i 425 OC This “Aerospace Series“ Prestandard has been drawn up under the responsibility of AECMA (The European Asso
4、ciation 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 Committee following comment by the Member countries. Subsequent to the publication of this Prestandard, the technical content sh
5、all not be changed to an extent that interchangeability is affected, physically or functionally, without re-identification of the standard. After examination and signature of the AECMA Standard Checking Centre (NPS) and formal agreement of the Official Services of the Member countries it will be sub
6、mitted 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. - Technopolis 54 - 199, rue Jean-Jacaues Rousseau - 921 38 ISSY-LES-MOULINEAUX CEDEX C3 Chairman I Comments should be sent within six months after the
7、date of Dublication to I I Edition approved for publication 1997-01-31 AECMA Gulledelle 94 B-1200 BRUXELLES Mr Arena I I aecma 191 STD-AECMA PREN Li25L-ENGL 1777 LO123LL OOL2L51 350 Page 3 prEN 4251 1 Scope This standard specifies the characteristics of self-locking, fixed 90“ corner anchor nuts, wi
8、th counterbore in heat resisting steel, silver plated. Classification : 1 100 MPa l) / 425 “C 2, 2 Normative references IS0 3221 IS0 5855-2 IS0 5858 IS0 8788 EN 2000 EN 2424 EN 2786 EN 3042 TR 3791 Aerospace - Nuts, anchor, self-locking, fixed, goocorner, with counterbore, with MJ threads, coated or
9、 non uncoated, classification 1 100 MPa / 235 OC, 1 1 O0 MPa 1315C or 1 100 MPa / 425C - Dimensions Aerospace - MJ threads - Part 2 : Limit dimensions for bolts and nuts Aerospace - Self-locking nuts with maximum operating temperature less than or equal to 425 “C - Procurement specification Aerospac
10、e - Fasteners - Tolerances of form and position for nuts Aerospace series - Quality assurance - EN aerospace products - Approval of the quality system of manufacturers Aerospace series - Marking of aerospace products Aerospace series - Electrolytic silver plating of fasteners 3, Aerospace series - Q
11、uality assurance - EN aerospace products - Qualification procedure Aerospace series - Materials for all metal self-locking nuts and thin wall inserts of temperature classes 425 “C 4, 1) Corresponds to the minimum stress which the nut is able to withstand at ambient temperature, without breaking or c
12、racking when tested with a bolt of a higher strength class. 2) Maximum temperature that the nut is able to withstand, without permanent alteration to its original charac- teristics, after ambient temperature has been restored. The maximum temperature is conditionned by the dimensions. 3) Published a
13、s AECMA Prestandard at the date of publication of this standard 4) Published as AECMA Technical Report at the date of publication of this standard Previous page is blank STD-AECMA PREN Li251-ENGL 1997 LO123L1 0012152 297 Page 4 prEN 4251 3 Required characteristics 3.1 Configuration - Dimensions - Ma
14、sses See figure 1 and table I. Dimensions and tolerances are: in conformity with IS0 3221, expressed in millimetres and apply after surface treatment. Details of form not stated are at manufacturers option. The cap shall remain joined (type of attachment at the users discretion) to the nut at the ma
15、ximum operating temperature. See test conditions in IS0 5858. 3.2 Tolerances of form and position 3.3 Materials TR 3791 3.4 Surface treatment EN 2786, thickness : - on external surfaces: 5 pm to 15 pm ; - on pitch diameter : 5 prn minimum for nuts MJ6 and larger. Nuts MJ5 and smaller shall show comp
16、lete coverage over complete profile. Remove sharp edges 0,1 to 0,4 Page 5 prEN 4251 1) These values in micrometres apply before to surface treatment. They do not apply to threads, punched holes or sheared edges, the surface texture of which will be as achieved by usual manufacturing methods. 2) Tool
17、ing marks are permitted in this area. Figure 1 Table 1 In accordance with IS0 5855-2. In the self-locking zone the tolerances apply before forming out-of-round Measured at sharp corners (chamfered) or point of tangency (radiused) Measured at rivet hole location I 4j Maximum protrusion of the bolt 5)
18、 Approximate values (kg/l O00 pieces), given for information purposes only. They apply to anchor nuts without cap _ STD-AECMA PREN Y251-ENGL 1997 = 1012311 001215V ObT Number of this standard Page 6 prEN 4251 Option Plain rivet holes Dimpled or countersunk rivet holes Plain rivet holes + cap Dimpled
19、 or countersunk rivet holes + cap 4 Designation EXAMPLE : Code - (hyphen) K B A Identity block I Description block NOTE : If necessary, the code 19005 shall be placed between the description block and the identity block. 5 Marking EN 2424, style N. See figure 1. 6 Technical specification IS0 5858 except for : - Approval of manufacturers : see EN 2000 ; - Qualification of products : see EN 3042.
