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Certification of Aerospace Products to international quality Standards
Certification of Aerospace Products to international quality Standards
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FPI : mfg batch size is 2110 parts.
FPI shall be carried out as per EN3152, tables 3 and 4.
In table 3, AQL for discontinuities is 0,065%.
In table 4, for mfg batch size ranging from 1201 to 3200 parts, we have a down arrow marked against AQL 0,065% sampling column to say that 200 parts shall be inspected.
HFS sampled 125 parts according to test report.
Could you please clarify?
For reusability test at 3 cycles, what is the bolt material (information missing in test report)?
Do we have additional lubrication for this test? If yes, which one?
It should be good to add units (N.m) in “Unit” box.
Many thanks in advance,
Best regards.
FPI : mfg batch size is 2110 parts.
FPI shall be carried out as per EN3152, tables 3 and 4.
In table 3, AQL for discontinuities is 0,065%.
In table 4, for mfg batch size ranging from 1201 to 3200 parts, we have a down arrow marked against AQL 0,065% sampling column to say that 200 parts shall be inspected.
HFS sampled 125 parts according to test report.
Could you please clarify?
• Reaction Howmet: I agree sampling was performed on 125 parts because our interpretation of the table 4 was the following for batch size between 1201 and 3200 sampling size is 125 parts (see sampling highlighted). It seems that it is a bad interpretation.
Supplement MBR.
Disagree completely with the interpretation in the comments about the sample size above.
Table 4 of the EN3152 is very clear about this.
If the production Batch size is 1201 to 3200 pieces the Sample size is 125 pieces (second column).
Table 3 gives a category of defects.
I totally agree that the Surface discontinuities falls in the AQL 0.065%.
AQL Acceptance quality limit (in percent nonconforming items or in nonconformities per hundred items “LQ10 column”)
See table 4 column 3 and 4 (AQL 0.065%). The third column indicates the AC (Acceptance number) at an AQL of 0.065 %.
The downward and upward arrows are placed in these columns here.
We see that with a batch size of up to 35000 pieces no nonconformities may be present ( 0 ).
With a batch size of 35001 to 500000, 1 nonconformities may be found and the batch is still acceptable.
So the up and down arrows don’t have anything to do with the sampling size, but just with the AC or LQ10 numbers.
If we look at the top of table 3, namely the characteristics which fall under the AQL 1.0% and go to table 4 with the batch size from 1201 to 3200 (sample size 125), we may find three nonconformities in the mentioned characteristics and the batch is still acceptable and so on with the AQL of 2.5% (7) and the 4.0% (10).
For information see ISO 2859-1:1999(en).
Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection)
For re-usability test at 3 cycles, what is the bolt material (information missing in test report)?
Do we have additional lubrication for this test? If yes, which one?
It should be good to add units (N.m) in “Unit” box.
• Reaction Howmet: TR Update with all the information.
I agree with all these detailed answers and updated documents.
Many thanks for this job.
One remark: for the future, please take into account the right sample size for NDT:
Reminder:
During the Mechanical – Technical Committee held in March 2019, the TC members resolved the following:
The interpretation of ISO2859-1 Table 2-A on single sampling plans for normal inspections is as follows:
For the following characteristics (AQL = 0,065% for discontinuities, single sampling level II, production batch size = 503 parts), the sampling size should be 200 parts, and not 80 parts, as a down arrow is marked against this production batch size. This down arrow means “Use sampling plan below (sample size and Ac)”. The sampling plan and Acceptance number referred to in this case are 200 parts and Acceptance 0 defect.
The attendees agreed unanimously that the manufacturers will not be requested to apply this sampling plan interpretation on past qualifications and qualifications currently under review by the Technical Committee. A statement presenting the accepted interpretation of Table 2-A of ISO2859-1 will be distributed to the manufacturers, though. They will be asked to provide a declaration that they now comply with this interpretation. This declaration will lift the conditions in relation with this issue set on current qualifications under review.
Howmet Fixations Simmonds have been informed of this interpretation and should have applied it.
Approved on my side.
Best regards.