feajob
Aerospace
- Aug 19, 2003
- 159
Hi,
I would like to understand something about S-Basis in MMPDS-03 (my knowledge is limited in M & P engineering field).
In order to be complaint with the FAR regulation (item 23.613), one economical method is to select materials in MMPDS that contain both A- & B- Basis allowables that are recognized in the industry. Unfortunately, I need to use Aluminum 7175-T74 (AMS 4149) with 3"-4" thickness from Table 3.7.11.0(b). The design mechanical properties are provided only for S-Basis.
I understood that S-Basis design values do not have reliable statistical significance. But, on page 9-10 of MMPDS-03, it is written that "Traditionally, the statistical assurance of S-Basis values has not been known. However, the statistical assurance with S-Basis values established since 1975 is known within the limitations of the qualification sample and the analysis method used to evaluate the data. Within those constraints S-Basis values established since 1975 may be viewed as estimated A-Basis values."
How can I make sure the S-Basis values for this specific Alloy is established before or after 1975?
I appreciate to know your opinion.
Thank you,
A.A.Y.
I would like to understand something about S-Basis in MMPDS-03 (my knowledge is limited in M & P engineering field).
In order to be complaint with the FAR regulation (item 23.613), one economical method is to select materials in MMPDS that contain both A- & B- Basis allowables that are recognized in the industry. Unfortunately, I need to use Aluminum 7175-T74 (AMS 4149) with 3"-4" thickness from Table 3.7.11.0(b). The design mechanical properties are provided only for S-Basis.
I understood that S-Basis design values do not have reliable statistical significance. But, on page 9-10 of MMPDS-03, it is written that "Traditionally, the statistical assurance of S-Basis values has not been known. However, the statistical assurance with S-Basis values established since 1975 is known within the limitations of the qualification sample and the analysis method used to evaluate the data. Within those constraints S-Basis values established since 1975 may be viewed as estimated A-Basis values."
How can I make sure the S-Basis values for this specific Alloy is established before or after 1975?
I appreciate to know your opinion.
Thank you,
A.A.Y.
