14 CFR §21.331

1. (a)A person may obtain from the FAA an export airworthiness approval to export a new aircraft engine, propeller, or article that is manufactured under this part if it conforms to its approved design and is in a condition for safe operation.
2. (b)A new aircraft engine, propeller, or article need not meet a requirement of paragraph (a) of this section if—
   1. (1)The importing country or jurisdiction accepts, in a form and manner acceptable to the FAA, a deviation from that requirement; and
   2. (2)The export airworthiness approval lists as an exception any difference between the aircraft engine, propeller, or article to be exported and its approved design.
3. (c)A person may obtain from the FAA an export airworthiness approval to export a used aircraft engine, propeller, or article if it conforms to its approved design and is in a condition for safe operation.
4. (d)A used aircraft engine or propeller need not meet a requirement of paragraph (c) of this section if—
   1. (1)The importing country or jurisdiction accepts, in a form and manner acceptable to the FAA, a deviation from that requirement; and
   2. (2)The export airworthiness approval lists as an exception any difference between the used aircraft engine or propeller to be exported and its approved design.