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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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EN3720-050:
1/ Hardness requirements on QTP is: “27 HRC TO 44 HRC WHICH CORRESPONDS TO 279 HV5 TO 435 HV5. ISO 7481”
Hardness requirement on QTR (Test Report 13770318) is from 320 to 410 HV5.
QTR requirement is tighter than QTP, so, no issue about that, but why is there a difference?
EN3720-070:
1/ FPI: for Acceptance, 200 parts should have been FP inspected. Only 125 parts were checked.
We have a down arrow marked against batch size “1201 to 3200” for AQL=0,065% (EN3752, tables 3 and 4).
Mfg batch size is: 2651.
2/ Reusability test (3 cycle test):
On QTR, minimum breakaway torque requirement is 0,4 N.m for all cycles.
As per EN3752, minimum breakaway torque requirements are: 1 N.m (1st cycle) and 0,6 N.m (2nd and 3rd cycles).
EN3720-080:
1/ Hardness requirements on QTP is: “27 HRC TO 44 HRC WHICH CORRESPONDS TO 279 HV5 TO 435 HV5. ISO 7481”
Hardness requirement on QTR (Test Report 13944972) is from 280 to 360 HV5.
QTR requirement is tighter than QTP, so, no issue about that, but why is there a difference?
2/ FPI: for Acceptance, 200 parts should have been FP inspected. Only 125 parts were checked.
We have a down arrow marked against batch size “1201 to 3200” for AQL=0,065% (EN3752, tables 3 and 4).
Mfg batch size is: 1900.
EN3720-100:
1/ Hardness requirements on QTP is: “27 HRC TO 44 HRC WHICH CORRESPONDS TO 279 HV5 TO 435 HV5. ISO 7481”
Hardness requirement on QTR (Test Report 13794478) is from 280 to 360 HV5.
QTR requirement is tighter than QTP, so, no issue about that, but why is there a difference?
2/ FPI: for Acceptance, 200 parts should have been FP inspected. Only 80 parts were checked.
We have a down arrow marked against batch size “1201 to 3200” for AQL=0,065% (EN3752, tables 3 and 4).
Mfg batch size is: 587.
3/ On QTR, minimum breakaway torque requirement is 1,4 N.m for all cycles.
As per EN3752, minimum breakaway torque requirements are: 2,4 N.m (1st cycle) and 1,4 N.m (2nd and 3rd cycles).
So, for 1st cycle, we have one nut which has a breakaway torque below 2,4 N.m: the fifth tested nut (2,1 N.m)
EN3723-030:
Nothing to report.
Many thanks in advance,
Best regards.
Hardness requirement:
Hardness required in the block “Dureté / Hardness is more restrictive than the hardness required by the ISO7481. Reason for this is the restrictive requirement it is coming from the internal Heat Treatment specification.
FPI: sampling size for Acceptance:
The difference in the samples size to be tested for acceptances has been accepted by me based on the stipulations in the AS / EN9133 publication and based on that the Quality Manual of ASD-Cert, page 23/62 “Qualification by analogy”. Material, design and manufacturing are identical (see my remark in the chapter “Substantiation by analogy”). The manufacturer has demonstrated by part testing that the products are compliant and this is supported by the statement of “Statement of no customer claim” also included in the ASD-Cert report, chapter “Additional Documents”.
Breakaway torque
This was a more difficult issue. The manufacturer has investigated this comment internally and has come to the conclusion that a mix of data has occurred. As a result, these incorrect data have entered the QTR’s. The affected QTR’s are now properly updated and uploaded in the ASD-Cert report. The mix of data has also been rectified internally. The mix of data has not affected the produced products, these are all acceptable.
Agreed for the first two answers (hardness and FPI).
QTR updates about breakaway torques for EN3720-070 and EN3720-100 are in line with EN3752, so, also agreed.
Many thanks.
Regards