TCM 1 392-3-2 LISI Aerospace [Bestas] Gazemir (TR) EN3444-050, -060, -080, -100

On ASD-CERT website, EN/AS9100 certificate validity is expired (11/06/2019).

On FAIR, for all EN3444 part references, in column “Character. Designator”, it is written “minor” for all characteristics.
How do we interpret “minor”?
If we consider ISO9154, table 3, dimensional characteristics have not the same category of defects.
Some dimensional characteristics are considered major with AQL = 1%, other dimensions are ranked as minor with AQL = 2,5% or 4%.
So, for acceptance, do we have sample size for dimensional inspections as per ISO9154, tables 3 and 4? On FAI, sampling was done as per ANSI/ASQ Z1.4 general control level II and WI-SYS-30, but we do not have AQL applied.
ISO9154 sampling (tables 3 and 4) is based on ISO2859-1, table II-A, single sampling, normal inspection. ISO2859-1 and ANSI/ASQ Z1.4 are really similar. From my point of view, this is the same way of sampling. Could you please confirm on your side?

• EN3444-050:

On FPI report for EN3444-050, batch size is 135 bolts.
20 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “91 to 150”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, since sample size (200) exceeds mfg batch size (135), a 100% FPI inspection should have been done instead of 20.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, Page 6, tensile test at ambient temperature: tensile test requirement written is 15,4 kN.
Minimum tensile requirement is 23,7 kN x 0,806 = 19,120 kN. Please see EN3444, clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(4,076²)[2-(4,076/4,48)²]=15,296 mm².
Minimum tensile load = (AtkRm)/1000 = (15,296x1x1250)/1000 = 19,12 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient (EN3444, clause 6.3), we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(15,296x1x1550)/1000]x0,806 = 19,12 kN.
Could you please correct this on QTR, page 6 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (15,296x1x1250)/1000 = 19,12 kN.
By applying allowance coefficient 0,806, we have: 19,12×0,806 = 15,4 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 6, for fatigue test, could you please precise which loads and frequency were applied?

QTR, page 7, minimum tensile value at elevated temperature requirement written is 12,32 kN.
Minimum hot tensile requirement is 19 kN x 0,806 = 15314 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5 and clause B.2.3. Could you please fix this? Actual values are compliant.
Indeed:
As per EN3444, clause 6.3, minimum tensile load at ambient temperature = 23700×0,806 = 19102 N.
As per ISO9154, table 5 and clause B.2.3, tensile load at ambient temperature = 0,8 times tensile test load at ambient temperature.
Thus, 23700×0,806×0,8 = 15281 N ? 15314 N.

QTR, page 7, minimum double shear load requirement written is 29,45 kN. In this case, this is the right value, since:
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x5² = 19,635 mm².
Shear load = (2AsRc)/1000 = (2×19,635x1550x0,806×0,6)/1000 = 29,45 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 8, minimum stress rupture load requirement written is 7,7 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 23700×0,806×0,5 = 9551 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.

• EN3444-060:

On FPI report for EN3444-060, batch size is 1009 bolts.
80 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “501 to 1200”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, 200 parts should have been FPI inspected instead of 80.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, page 9, for fatigue test, could you please precise which loads and frequency were applied?

QTR, page 10, minimum double shear load requirement written is 51,5 kN. In this case, this is the value for 1550 MPa strength class bolts, not for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x6² = 28,274 mm².
Shear load = (2AsRc)/1000 = (2×28,274x1550x0,806×0,6)/1000 = 42,411 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.
Anyway, actual double shear loads are compliant, but it should be preferable to correct minimum double shear load requirement.

QTR, page 11, minimum stress rupture load requirement written is 13,62 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 33700×0,806×0,5 = 13580 N.
So, in this case, stress rupture load requirement is in line with ISO9154.

• EN3444-080:

On FPI report for EN3444-080, batch size is 203 bolts.
32 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “151 to 280”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, 200 parts should have been FPI inspected instead of 32.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, page 12, for fatigue test, could you please precise which loads and frequency were applied?
QTR, Page 12, tensile test at ambient temperature: tensile test requirement written is 41,97 kN.
Minimum tensile requirement is 64,6 kN x 0,806 = 52068 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(6,845²)[2-(6,845/7,350)²]=41,682 mm².
Minimum tensile load = (AtkRm)/1000 = (41,682x1x1250)/1000 = 52,1 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient, we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(41,682x1x1550)/1000]x0,806 = 52,1 kN.
Could you please correct this on QTR, page 12 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (41,682x1x1250)/1000 = 52,1 kN.
By applying allowance coefficient 0,806, we have: 52,1×0,806 = 41,99 kN ? 41,97 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This is the reason why EN3444, clause 6.3 states that “apply the coefficient 0,806”.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 13, minimum tensile value at elevated temperature requirement written is 33,57 kN.
Minimum hot tensile requirement is 51,7 kN x 0,806 = 41670 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5. Could you please fix this?
We can do the math as follows as well:
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.3, tensile test load at elevated temperature = 0,8 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 64600×0,806×0,8 = 41654 N ? 41670 N (see above).

QTR, page 13, minimum double shear load requirement written is 75,36 kN. In this case, this is the right value for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x8² = 50,265 mm².
Shear load = (2AsRc)/1000 = (2×50,265x1550x0,806×0,6)/1000 = 75,36 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 14, minimum stress rupture load requirement written is 20,985 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 64600×0,806×0,5 = 26034 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.
*
• EN3444-100:

QTR, page 15, for fatigue test, could you please precise which loads and frequency were applied?
QTR, Page 15, tensile test at ambient temperature: tensile test requirement written is 65,63 kN.
Minimum tensile requirement is 101 kN x 0,806 = 81400 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(8,557²)[2-(8,557/9,188)²]=65,136 mm².
Minimum tensile load = (AtkRm)/1000 = (65,136x1x1250)/1000 = 81,4 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient, we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(65,136x1x1550)/1000]x0,806 = 81,4 kN.
Could you please correct this on QTR, page 15 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class bolts.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (65,136x1x1250)/1000 = 81,4 kN.
By applying allowance coefficient 0,806, we have: 81,4×0,806 = 65,6 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 16, minimum tensile value at elevated temperature requirement written is 52,5 kN.
Minimum hot tensile requirement is 80,8 kN x 0,806 = 65124 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5. Could you please fix this?
We can do the math as follows as well:
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.3, tensile test load at elevated temperature = 0,8 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 101000×0,806×0,8 = 65124 N.

QTR, page 16, minimum double shear load requirement written is 117,81 kN. In this case, this is the right value for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x10² = 78,540 mm².
Shear load = (2AsRc)/1000 = (2×78,540x1550x0,806×0,6)/1000 = 117,81 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 17, minimum stress rupture load requirement written is 32,81 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 101000×0,806×0,5 = 40703 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.

On FPI report for EN3444-100, batch size is 99 bolts.
20 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “91 to 150”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, since sample size (200) exceeds mfg batch size (99), a 100% FPI inspection should have been done instead of 20.
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

My apologies for this really long text, but I tried to explain the best I can.
Feel free to contact me if it is not clear.
Many thanks,
Regards.
Julien

3 Replies to “TCM 1 392-3-2 LISI Aerospace [Bestas] Gazemir (TR) EN3444-050, -060, -080, -100”

Julien Gauther says:

27/01/2020 at 7:17 pm

On ASD-CERT website, EN/AS9100 certificate validity is expired (11/06/2019).

On FAIR, for all EN3444 part references, in column “Character. Designator”, it is written “minor” for all characteristics.
How do we interpret “minor”?
If we consider ISO9154, table 3, dimensional characteristics have not the same category of defects.
Some dimensional characteristics are considered major with AQL = 1%, other dimensions are ranked as minor with AQL = 2,5% or 4%.
So, for acceptance, do we have sample size for dimensional inspections as per ISO9154, tables 3 and 4? On FAI, sampling was done as per ANSI/ASQ Z1.4 general control level II and WI-SYS-30, but we do not have AQL applied.
ISO9154 sampling (tables 3 and 4) is based on ISO2859-1, table II-A, single sampling, normal inspection. ISO2859-1 and ANSI/ASQ Z1.4 are really similar. From my point of view, this is the same way of sampling. Could you please confirm on your side?

• EN3444-050:

On FPI report for EN3444-050, batch size is 135 bolts.
20 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “91 to 150”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, since sample size (200) exceeds mfg batch size (135), a 100% FPI inspection should have been done instead of 20.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, Page 6, tensile test at ambient temperature: tensile test requirement written is 15,4 kN.
Minimum tensile requirement is 23,7 kN x 0,806 = 19,120 kN. Please see EN3444, clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(4,076²)[2-(4,076/4,48)²]=15,296 mm².
Minimum tensile load = (AtkRm)/1000 = (15,296x1x1250)/1000 = 19,12 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient (EN3444, clause 6.3), we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(15,296x1x1550)/1000]x0,806 = 19,12 kN.
Could you please correct this on QTR, page 6 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (15,296x1x1250)/1000 = 19,12 kN.
By applying allowance coefficient 0,806, we have: 19,12×0,806 = 15,4 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 6, for fatigue test, could you please precise which loads and frequency were applied?

QTR, page 7, minimum tensile value at elevated temperature requirement written is 12,32 kN.
Minimum hot tensile requirement is 19 kN x 0,806 = 15314 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5 and clause B.2.3. Could you please fix this? Actual values are compliant.
Indeed:
As per EN3444, clause 6.3, minimum tensile load at ambient temperature = 23700×0,806 = 19102 N.
As per ISO9154, table 5 and clause B.2.3, tensile load at ambient temperature = 0,8 times tensile test load at ambient temperature.
Thus, 23700×0,806×0,8 = 15281 N ? 15314 N.

QTR, page 7, minimum double shear load requirement written is 29,45 kN. In this case, this is the right value, since:
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x5² = 19,635 mm².
Shear load = (2AsRc)/1000 = (2×19,635x1550x0,806×0,6)/1000 = 29,45 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 8, minimum stress rupture load requirement written is 7,7 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 23700×0,806×0,5 = 9551 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.

• EN3444-060:

On FPI report for EN3444-060, batch size is 1009 bolts.
80 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “501 to 1200”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, 200 parts should have been FPI inspected instead of 80.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, page 9, for fatigue test, could you please precise which loads and frequency were applied?

QTR, page 10, minimum double shear load requirement written is 51,5 kN. In this case, this is the value for 1550 MPa strength class bolts, not for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x6² = 28,274 mm².
Shear load = (2AsRc)/1000 = (2×28,274x1550x0,806×0,6)/1000 = 42,411 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.
Anyway, actual double shear loads are compliant, but it should be preferable to correct minimum double shear load requirement.

QTR, page 11, minimum stress rupture load requirement written is 13,62 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 33700×0,806×0,5 = 13580 N.
So, in this case, stress rupture load requirement is in line with ISO9154.

• EN3444-080:

On FPI report for EN3444-080, batch size is 203 bolts.
32 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “151 to 280”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, 200 parts should have been FPI inspected instead of 32.
This topic was already discussed in ASD-CERT Mechanical Workshop minutes (released in March 2019).
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

QTR, page 12, for fatigue test, could you please precise which loads and frequency were applied?
QTR, Page 12, tensile test at ambient temperature: tensile test requirement written is 41,97 kN.
Minimum tensile requirement is 64,6 kN x 0,806 = 52068 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(6,845²)[2-(6,845/7,350)²]=41,682 mm².
Minimum tensile load = (AtkRm)/1000 = (41,682x1x1250)/1000 = 52,1 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient, we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(41,682x1x1550)/1000]x0,806 = 52,1 kN.
Could you please correct this on QTR, page 12 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (41,682x1x1250)/1000 = 52,1 kN.
By applying allowance coefficient 0,806, we have: 52,1×0,806 = 41,99 kN ? 41,97 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This is the reason why EN3444, clause 6.3 states that “apply the coefficient 0,806”.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 13, minimum tensile value at elevated temperature requirement written is 33,57 kN.
Minimum hot tensile requirement is 51,7 kN x 0,806 = 41670 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5. Could you please fix this?
We can do the math as follows as well:
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.3, tensile test load at elevated temperature = 0,8 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 64600×0,806×0,8 = 41654 N ? 41670 N (see above).

QTR, page 13, minimum double shear load requirement written is 75,36 kN. In this case, this is the right value for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x8² = 50,265 mm².
Shear load = (2AsRc)/1000 = (2×50,265x1550x0,806×0,6)/1000 = 75,36 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 14, minimum stress rupture load requirement written is 20,985 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 64600×0,806×0,5 = 26034 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.
*
• EN3444-100:

QTR, page 15, for fatigue test, could you please precise which loads and frequency were applied?
QTR, Page 15, tensile test at ambient temperature: tensile test requirement written is 65,63 kN.
Minimum tensile requirement is 101 kN x 0,806 = 81400 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5.
If we do the math with formulae mentioned in ISO9154 and considering 1250 MPa strength class:
At = (pi/4)(d3)²[2-(d3/d2)²]= (pi/4)(8,557²)[2-(8,557/9,188)²]=65,136 mm².
Minimum tensile load = (AtkRm)/1000 = (65,136x1x1250)/1000 = 81,4 kN.
If we consider ISO9154 tensile strength and 0,806 coefficient, we have the same result:
Minimum tensile load = [(AtkRm)/1000]x0,806 = [(65,136x1x1550)/1000]x0,806 = 81,4 kN.
Could you please correct this on QTR, page 15 and CoC Annex 4 as well? Tensile test values are compliant and this is the most important.
I think that manufacturer considered allowance coefficient 0,806 directly on 1250 MPa strength class bolts.
If we do the following math:
Minimum tensile load = (AtkRm)/1000 = (65,136x1x1250)/1000 = 81,4 kN.
By applying allowance coefficient 0,806, we have: 81,4×0,806 = 65,6 kN, as mentioned in QTR.
Unfortunately, this allowance coefficient applies on tensile load requirements in ISO9154, I mean, on associated tensile requirements for 1550 MPa strength class bolts.
Strength class ratio = (1250/1550) = 0,806.
This coefficient is necessary for converting ISO9154 (1550 MPa strength class bolts) tensile requirements into 1250 MPa strength class bolt tensile requirements.

QTR, page 16, minimum tensile value at elevated temperature requirement written is 52,5 kN.
Minimum hot tensile requirement is 80,8 kN x 0,806 = 65124 N. Please see EN3444 clause 6.3 associated with ISO9154, table 5. Could you please fix this?
We can do the math as follows as well:
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.3, tensile test load at elevated temperature = 0,8 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 101000×0,806×0,8 = 65124 N.

QTR, page 16, minimum double shear load requirement written is 117,81 kN. In this case, this is the right value for 1250 MPa strength class bolts.
Shear strength cross-sectional area = As = (pi/4)(d)² = (pi/4)x10² = 78,540 mm².
Shear load = (2AsRc)/1000 = (2×78,540x1550x0,806×0,6)/1000 = 117,81 kN.
With Rc = 1550×0,806×0,6 or Rc = 1250×0,6.

QTR, page 17, minimum stress rupture load requirement written is 32,81 kN.
As per EN3444, clause 6.3, minimum tensile strength test loads: apply the coefficient 0,806.
As per ISO9154, clause B.2.5, stress rupture test load at elevated temperature = 0,5 times tensile test load at ambient temperature.
Thus, the minimum stress rupture test load = 101000×0,806×0,5 = 40703 N.
Could you please correct this? Since load applied is not the right one, this test shall be performed again with right load.

On FPI report for EN3444-100, batch size is 99 bolts.
20 bolts were FPI inspected.
However, as per ISO9154, tables 3 and 4, AQL = 0,065% for discontinuities detection.
Thus, in ISO9154 table 4, column AQL 0,065%, we have a down arrow marked against production batch size “91 to 150”. This down arrow means: “Use sampling plan below (sample size and Ac)”.
In the case of sample size is equal to or greater than the batch size, a 100% inspection shall be performed.
In this case, down arrow leads to sample 200 parts (with Ac = 0). So, since sample size (200) exceeds mfg batch size (99), a 100% FPI inspection should have been done instead of 20.
These QTR was done before March 2019 since it is dated January 2019. This might explain why there is this sampling issue for FPI. If it is, could you please confirm that actions have been taken to apply right sampling plans?

My apologies for this really long text, but I tried to explain the best I can.
Feel free to contact me if it is not clear.
Many thanks,
Regards.
Julien

Philip Edwards says:

19/03/2020 at 9:46 am

QTR updated to address comments.
answer to comments is uploaded to the QTR section of this report

Julien Gauther says:

20/03/2020 at 2:24 pm

Hello Phil,

Many thanks for these updates.
All is clear for me now.
Many thanks to LISI AEROSPACE IZMIR as well.
Best regards.
Julien

TCM 1 392-3-2 LISI Aerospace [Bestas] Gazemir (TR) EN3444-050, -060, -080, -100

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