Testing and approval may be appropriate when-

1. (a) The contractor has not previously furnished the product to the Government;

2. (b) The contractor previously furnished the product to the Government, but-

   1. (1) There have been subsequent changes in processes or specifications;

   2. (2) Production has been discontinued for an extended period of time; or

   3. (3) The product acquired under a previous contract developed a problem during its life;

3. (c) The product is described by a performance specification; or

4. (d) It is essential to have an approved first article to serve as a manufacturing standard.