1、 - STD.AECMA PREN 3905-ENGL 1777 10123LL 0011553 7bT D Edition approved for publication AECMA STANDARD NORME AECMA AECMA NORM Comments should be sent within six months C8 Chairman after the date of publication to prEN 3905 Edition P 1 April 1997 PUBLISHED BY THE EUROPEAN ASSOCIATION OF AEROSPACE IND
2、USTRIES (AECMA) Gulledelle 94 - 8-1 200 BRUXELLES - Tel. (32) 2 775 81 1 O - Fax. (32) 2 775 81 11 ICs : 49.040.20 Descriptors : ENGLISH VERSION Aerospace series Six lobe recesses for bolts Technical specification Srie arospatiale Empreintes six lobes pour vis Spcification technique Luft- und Raumfa
3、hrt Sechs-Bogenzahn-lnnenantrieb fr Schrauben Technische Lieferbedingungen 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 technicall
4、y 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 shall not be changed to an extent that interchangeability is affected, physically or functionally, without re-identificat
5、ion 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 submitted as a draft European Standard to CEN (European Committee for Standardization) for formal vote. 1997-04-30 AECMA G
6、ulledelle 94 B-1200 BRUXELLES Mr Feltham aecma 1997 STD.AECMA PREN 3705-ENGL 1777 W 1012311 0011554 8Tb 9 Page 3 prEN 3905 : 1997 1 Scope This standard specifies the characteristics and qualification requirements for six lobe recesses defined by EN 391 1 for bolts. The requirements of this specifica
7、tion are additional to the requirements of the relevant bolt technical specification. 2 Normative references IS0 5855-2 EN 3911 EN 3042 Aerospace - MJ threads - Part 2 : Limit dimensions for bolts and nuts Aerospace series - Six lobe recess - Geometrical definition 1) Aerospace series - Quality assu
8、rance - EN aerospace products - Qualification procedure 3 Qualification See table 1. 4 Requirements See table 1. 5 Apparatus See figure 1. 5.1 Test block Material : steel HRC 2 40 5.2 Nut - thread to IS0 5855-2 ; - tensile strengh class : no requirement ; - material : no requirement. 1) Published as
9、 AECMA Prestandard at the date of publication of this standard Previous page is blank STDmAECMA PREN 3705-ENGL 1777 L0123LL 0011555 732 Nominal diameter mm Page 4 prEN 3905 : 1997 Wrench torque 1) Nm Recess code Table 1 : Technical requirements and test methods 7 a 10 Characteristic Wrench feature t
10、est at ambient temperature 40 40 60 45 115 50 Requirement The wrench torque specified in table 2 shall be applied to all bolts with internal drive recesses in accordance with EN 391 1 (six lobe recess). Number of cycles : 15. The driving recess shall not display any permanent damage. Inspection and
11、test method The bolt head shall have two flats machined in it, to give a clearance of between 0,05 mm and 0,l mm from the test block (see figure 1). Lubricate both the bolt and nut threads with clean engine oil. Insert bolt (with flats) into test block. Torque tighten nut and bolt assembly in the te
12、st block in accordance with table 2. The test block shall then be suitably held (e.g. bench vice). Apply the torque load with a driver according to EN aerospace series using a suitably calibrated torque wrench (taking care not to apply any bending moment to the recess), alternating clockwise and cou
13、nterclockwise (one cycle). Table 2 : Wrench torque values I I 5 I 13.8 I 27 I I I I 6 I 24 I 30 1 I i) Based on two and half times the torque required to induce 75 % of the 0,2 % proof stress in a bolt of class 900 MPa Wo,* % = 590 MPa) Slot width = Bolt head diameter - 1 mm Sample size 2 pitch min. I_ Slot depth = Boit head height - I mm L t- I/ / Chamfer according to the bolt head radius +O25mm Bolt diameter + o;,o mm 5 D : Nominal diameter of the bolt Figure 1 : Test block
