About effectivity cutback

Effectivity cutback is the result of modifying an effectivity range when you introduce a new part to replace an old part in a released Usage BOM structure. In this case, it is necessary to reduce (cut back) or make room for the effectivity range of the old part so that it does not overlap with the effectivity of the new part.For example, Engine BS4 has effectivity ranging from days 01–20 and Engine BS6 has effectivity ranging from days 12–20. If Engine BS4 is replaced by Engine BS6, both engines are effective from days 12–20. To resolve this, the effectivity of Engine BS4 must be cut back or adjusted to end before Engine BS6 becomes effective, that is, days 01–11. This ensures that Engine BS4 is effective from days 01–11, and Engine BS6 is effective from days 12–20.Consider the following scenario:You have a released structure with effectivity propagation resulting from a change notice. You modify this structure in context of a new change notice by replacing an existing part. This existing part, the impacted item, has a partial effectivity overlap with the new part, the solution item. In this scenario, the new part, or the solution item, inherits its element effectivity from the active change.In the following example, the part GA WINDSHIELD (created in change notice 1, with a release effectivity starting March 1, 2022) is replaced with the part TOUGHENED WINDSHIELD (created in change notice 2, with a release effectivity starting March 15, 2022). The element effectivity of the part GA WINDSHIELD (now revised to Usage Revision B) is cut back to a date before the part TOUGHENED WINDSHIELD (having Usage Revision A) is effective.The following graphic explains various use cases for effectivity cutback, where each block represents the effective period of the part and its overlap with the release effectivity of the change notice.Sometimes, when a new engineering change notice is created, its effectivity completely overlaps with the effectivity of the released part (Part 3 and Part 4 in the image). If you want to modify this released part, its part usage is first revised and then updated.For example, consider that the part Foot Board with quantity 2 was created and released in the context of change notice 1. This part is effective starting March 1, 2002. Now, the part Foot Board is updated to change its quantity to 4 in the context of change notice 2, a new change notice. The release effectivity of change notice 2 is the same as that of change notice 1. Therefore, before updating Foot Board, it is first revised and then updated, and the quantity of its part usage is set as 4.Now, after the quantity is updated, the effectivity of change notice 2 is changed such that it is effective starting May 1, 2002, to have a partial overlap instead of full overlap. In such a scenario, you must repropagate the effectivity so that Foot Board gets the new effectivity date. On doing so, Foot Board is split into two usages due to a partial overlap of effectivity dates. The old, revised part usage is effective from March 1, 2022, to April 30, 2022, while the new part usage created is effective starting May 1, 2022.