19 C.F.R. § 122.136
(b) Use of copies. The two copies of the outgoing stores list shall be used as follows:
(2) One copy must be filed either with the outgoing cargo manifest (for aircraft required to clear) or with Customs before departing, as provided in § 122.133(c).
In both cases, the third copy of the inward stores list shall be filed with the outgoing stores list. (See § 122.133(c)).