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Conditions for approval required by: Julien Gauther
Certification of Aerospace Products to international quality Standards
Certification of Aerospace Products to international quality Standards
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In PFC, could you please tell us which issue of EN3753 has been considered?
In QTR, clause 5.1, product drawing shown comes from EN3753:1993. Could you please replace it by the drawing from EN3753:2010?
Apparently, there is a typo for rivet hole dimension in EN3753:2010: it seems that it is written “2xØ5” instead of “2xØS”. However, EN3753:1993 is correct on this point.
Tensile test at 100%: as per ISO7481, test bolt shall be made out of alloyed steel with strength class greater than that of the nut to be tested and cadmium plated.
In QTR, test bolt is made out of Inconel 718 with 1100 MPa UTS (strange UTS for Inconel 718 by the way), passivated. Could you please clarify? The related picture seems to show a stainless steel or Inconel test bolt without any surface treatment (or passivated aspect).
Many thanks in advance,
Best regards.
On behalf of Geneviève Lacombe please find below the reply to your questions :
In PFC, could you please tell us which issue of EN3753 has been considered?
Please find the PFC updated see file enclosed “Flowchart EN3753-040 010421”
In QTR, clause 5.1, product drawing shown comes from EN3753:1993. Could you please replace it by the drawing from EN3753:2010?
Apparently, there is a typo for rivet hole dimension in EN3753:2010: it seems that it is written “2xØ5” instead of “2xØS”. However, EN3753:1993 is correct on this point.
Drawing of 1993 maintain because the drawing of the revision of 2010 is not correct . With the drawing of 2010 the dimension of the rivet hole must be 5 mm, this dimension is incompatible with the product . Moreover , in the table 1 of revision 2010 the dimension S is maintained , it must be 2.5 which is correct . Standard EN3753 revision 2010 must be reviewed. A revision must be submitted to ASD/STAN.
Tensile test at 100%: as per ISO7481, test bolt shall be made out of alloyed steel with strength class greater than that of the nut to be tested and cadmium plated.
I don’t agree there is no requirement on the raw material of the test bolt and that coating . The only requirement is that the strength must be greater than the nut. See below extract of the ISO 7481.
ISO 7481:2000(E)
4 © ISO 2000 – All rights reserved
3.2.2 Method
The test shall be carried out at ambient temperature.
For floating nuts, extract the nut from the cage or channel.
Lubricate the mandrel and nut (or threaded part) threads as stated in Table 1 (if necessary). Screw, with or without
a wrench, the threaded mandrel into the nut or threaded part up to a minimum engagement of three turns.
Move the collar into contact with the bearing surface.
Evaluate the out-of-squareness by means of a feeler gauge whose thickness corresponds to the permissible
squareness error permitted by the dimensional standard, the drawing or the procurement specification.
3.3 Axial load test
3.3.1 Test device
The test device is illustrated in Figure 3.
The test device includes the following elements:
a) a bearing plate in steel, heat-treated to a hardness W 40 HRC;
b) a conical washer (for testing countersunk nuts);
c) a bolt with characteristics as follows:
1) threads: in accordance with ISO 5855-2,
2) tensile strength class: greater than that of the nut under test,
3) material and coating: no specific requirement.
3.3.2 Method
Table 1 of ISO 7481 is only applicable to measurement of locking torque see paragraph 3.9.1
In QTR, test bolt is made out of Inconel 718 with 1100 MPa UTS (strange UTS for Inconel 718 by the way), passivated. Could you please clarify?The related picture seems to show a stainless steel or Inconel test bolt without any surface treatment (or passivated aspect).
It is a mistake in the QTR. The strength class of the test bolt used was 1500 MPa. We used INCONEL 718 test bolt in order to be sure to achieve the value requested during the tensile test at 100% without any damage on the bolt. So in case of damage of the assembly there is no interpretation on the test itself , we are sure that there is no damage on the bolt. During this test we doesn’t measure the locking torque so the coating are no impact on the test itself.
The related picture seems to show a stainless steel or Inconel test bolt without any surface treatment (or passivated aspect). Agree test bolts were passivated.
The test bolt used
Many thanks in advance,
Best regards.
G. Lacombe/N. Richard
Dear Mrs Lacombe, Mrs Richard,
Many thanks for your detailed answers.
Drawing of 1993 maintain because the drawing of the revision of 2010 is not correct . With the drawing of 2010 the dimension of the rivet hole must be 5 mm, this dimension is incompatible with the product . Moreover , in the table 1 of revision 2010 the dimension S is maintained , it must be 2.5 which is correct . Standard EN3753 revision 2010 must be reviewed. A revision must be submitted to ASD/STAN.
=> Agreed.
It is a mistake in the QTR. The strength class of the test bolt used was 1500 MPa. We used INCONEL 718 test bolt in order to be sure to achieve the value requested during the tensile test at 100% without any damage on the bolt. So in case of damage of the assembly there is no interpretation on the test itself , we are sure that there is no damage on the bolt. During this test we doesn’t measure the locking torque so the coating are no impact on the test itself.
=> Agreed.
I am happy with, so, approved on my side.
Best regards,