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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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• Qualification 768 – QTR N°8646
Self-locking torque at ambient temperature (15 cycles – qualification).
In QTR, 1st cycle minimum breakaway torque requirement is 0,2 N.m.
As per EN3752, table 7, note a, minimum breakaway torque is 0,1 N.m for all 15 cycles.
0,2 N.m 1st cycle minimum breakaway torque is applicable for the first cycle of three cycle test. (see EN3752, table 7, note b)
In QTR, 2nd and 3rd cycle minimum breakaway torque requirement is 0,12 N.m.
As per EN3752, table 7, note a, minimum breakaway torque is 0,1 N.m for all 15 cycles.
0,12 N.m 2nd and 3rd cycle minimum breakaway torque is applicable for the second and third cycle of three cycle test. (see EN3752, table 7, note c)
Anyway, 0,2 N.m and 0,12 N.m minimum breakaway torques are stricter, just something to point out and to correct in the future.
Since we have a change of surface treatment source, is it necessary to perform axial load after 425°C baking and reusability test, five cycles, after 425°C baking? Maybe these kind of tests performed at ambient temperature are enough to qualify the change of surface treatment subcontractor.
• On Acceptance Test Report (Test Report OF: 14031480):
Hardness: on TR, page 1/4, hardness requirement is 320 to 410 HV5. The 3 values measured are in line.
However, some hardness values on page 2/4 exceed the maximum required in page 1/4 (410 HV5).
HRC values (obtained by converting HV5 into HRC) are in line with EN3752 (for nuts formed from sheet or strip, which is the case, HRC requirement, in that case, is from 27 to 44 HRC). Could you please clarify?
Sampling done for visual, dimensional and FPI is 315 nuts.
These samplings are stricter than EN3752, tables 3 and 4.
Mfg batch size is 10337 nuts.
If we look at table 3, AQL = 0,065% for discontinuities.
Table 4 shows up arrow marked against “10001 to 35000” batch size. This up arrow is applicable for sampling plan (Acceptance number and sample size). Thus, sample size of 200 parts is in line with EN3752.
Anyway, samplings that were performed are tougher than EN3752. So, this is just something to point out.
Self-locking torque at ambient temperature (3 cycles – acceptance).
In TR, 1st cycle minimum breakaway torque requirement is 0,12 N.m.
As per EN3752, table 7, note b, minimum breakaway torque is 0,2 N.m for the first cycle of three cycle test.
Actual minimum breakaway torque values are in line with 0,2 N.m minimum. So, just something to point out and to correct in the future.
In TR, 2nd and 3rd cycle minimum breakaway torque requirement is 0,12 N.m.
As per EN3752, table 7, note c, minimum breakaway torque is 0,12 N.m for the 2nd and 3rd cycles of three cycle test. So, this is in line.
Many thanks in advance,
Regards.
Julien
Hello Julien,
in the attachments (TR) the response to your comments has been changed.
with regard to hardness, the 3mm nut is obtained from sheet metal the values ??are compliant.
for the change of subcontractor I do not ask for hot tests the PQ being always valid.
Regards.
Antoine
ARCONIC St COSME replied to these comments on Friday, January 31, 2020.
Test Report has been updated accordingly.
See TR “OF 14031480 rev: 4” attached (“SSCO0004P_620013112530” pdf file in QTR section).
This is good for me now.
Many thanks.
Regards.
Julien
Many thanks Antoine for this clarification.
Regards,
Julien