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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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QTR, test matrix, tensile test on bolts: ISO9152, clause 5.4.1 does not have a restriction on drilled shank bolts as it is actually the case for fatigue test.
QTS, tensile test sample size: could you please replace 4 by 5 parts? Hopefully, 5 parts have been tensile tested.
QTR, test matrix, fatigue test on bolts: EN3820, clause 6.3 only removes double shear test. I think we are talking about EN3820, clause 5.4.3, sub-clause d). This clause deals with “drilled shank”, but not “drilled thread” (for me, there is a difference between NAS4004 and ISO9152).
In addition, QTR clause 6.2.3 does mention ISO9152, clause 5.4.3.
From my point of view, if loaded area does not contain any holes, mechanical tests can be carried out.
For fatigue test, ISO9152 specifies a restriction when bolts have drilled shank. For me, it means, drilled shank in the axis (axial bore, such as EN3740 with diameter equal and greater than MJ12 and bolts with holes in “smooth” shank areas)
Many thanks in advance
Best regards
Julien
Thank you for these comments and we agree to correct the QTS and QTR documents as follows:
1. Tensile test on finished part is not required according to paragraph 5.4.1 d . The thread is too short and therefore the hole is close to the working area. However, the test works on an undrilled part and these results seem preferable to a test on a specimen.
2. Agreed, the witness testing sampled 4 parts but the full QTR has results for 5 samples. I have corrected the QTS and uploaded QTS issue 2.
3. The QTR Test matrix have been updated with paragraph 5.4.3 instead of 6.3 for the fatigue test.
4. We understand your point of view but in our opinion the drilling can have an influence on the load distribution in the threaded adaptors for example (probably slight but different from an undrilled part). Moreover, because of the short thread, the hole is close to the working area during the test and can potentially have an impact on the failure. For us the test is not required. However, since our intention was to qualify the entire standard and not have restrictions on drilled parts only, we performed the test on an undrilled part to prove that the fatigue test is compliant. The results are in the QTR. Also, we have modified the QTR by specifying that the fatigue tests are “Performed on specimen part” in the Test Matrix and in § 6.2.3 Tension fatigue strength.
Many thanks again Keith and Nicolas.
All is fine for me now, so, approved from my side.
Have a nice day
Regards
Julien