19 CFR 122.76 - Shipper's Export Declarations and inspection certificates.
(a) Shipper's Export Declarations - (1) Other than shipments to Puerto Rico. For shipments other than to Puerto Rico, at the time of clearance, the aircraft commander or agent shall file with the port director of the departure airport any Shipper's Export Declarations required by the Bureau of the Census (see 15 CFR part 30).
(2) Shipments to Puerto Rico. For flights carrying shipments to Puerto Rico from the U.S., the aircraft commander or agent shall file any Shipper's Export Declarations required by the Bureau of the Census (see 15 CFR part 30) upon arrival in Puerto Rico with the port director there.
(b) Inspection certificates. The aircraft commander or authorized agent shall deliver a proper export inspection certificate issued by the Veterinary Service, Animal and Plant Inspection Service, Department of Agriculture (9 CFR part 91), to the Customs officer in charge at the time of departure of any aircraft carrying horses, mules, asses, cattle, sheep, swine, or goats.