I would hold out until an official interpretation was handed down on that.
The fillet weld qualification only provides evidence the weld contains no unacceptable defects such as incomplete fusion, porosity, unacceptable contours, etc. The fillet macroetch or break test provides no information with regards to the strength or other mechanical properties of the weld.
The mechanical properties of the combination of filler metal and base metal can only be determined by using destructive mechanical tests such as the reduced section tensile test.
A welding engineer, welding inspector, or welding consultant has to keep in mind that it is their responsibility to ensure their activities protect the interests and safety of the public and meet the minimum requirements of the applicable welding standard. I would say it is irresponsible for a professional to proceed with production without verifying the WPS has the demonstrated ability to produce acceptable mechanical properties.
I read and understand clause 3.12 to require the qualification effort to include both strength and degree of soundness determinations. To quote, "The WPS qualification tests required in Part C are devised to determine the strength and degree of soundness of welds made by a specific WPS." I take special notice that the clause includes the word "and" between the words "strength" and the words "and degree of soundness". It is the opening paragraph on the subject of WPS qualification and applies equally to all weld types.
Clause 3.14 directs the reader's attention to Table 3.1. It begins with; "Change greater than the limits set in Table 3.1 shall be considered essential changes in a WPS and shall require qualification of the altered WPS. Table 3.1 requires a groove weld. No mention of a fillet weld is noted.
I spoke with the chair of the D1 committee several years ago on this subject as it related to the structural welding codes. His position was any welding engineer that is worth his salt knows that one must demonstrate the mechanical properties are met before qualifying a WPS for fillet welds.
The structural welding codes, like any welding code or standard, are not perfect. I think one must have a reasonable understanding of the purpose of qualifying WPS and the means employed to qualify a WPS. The fact that a weld is uniform and has a reasonable profile offers no assurance the weld has the necessary mechanical properties to provide useful service. The mechanical properties can only be established by mechanical testing.
The qualification of a fillet weld fails to establish the mechanical properties that can be expected with a specific combination of base metal and filler metal. One can produce a perfectly fine looking weld that fails miserably when tested for tensile strength or when attempting to pass a guided bend test. After all, once again, we are talking about aluminum, almost a metal.
Best regards - Al