Converts stearoyl-ACP to oleoyl-ACP by introduction of a cis double bond between carbons 9 and 10 of the acyl chain (By similarity). Exhibits delta-9 palmitoyl-[acyl-carrier-protein] desaturase (PAD) activity. Involved in omega-7 monounsaturated fatty acid biosynthesis, especially in the endosperm oil (PubMed:27681170). 2 H(+) + O2 + octadecanoyl-[ACP] + 2 reduced [2Fe-2S]-[ferredoxin] = (9Z)-octadecenoyl-[ACP] + 2 H2O + 2 oxidized [2Fe-2S]-[ferredoxin] Binds 2 Fe(2+) ions per subunit. Lipid metabolism; fatty acid metabolism. Homodimer. Preferentially expressed in roots and flowers. Accumulates in maturing endosperm. Activated by MYB115 and MYB118 in the endosperm. Reduced omega-7 fatty acids accumulation in the endosperm. The endosperm oil of double mutant aad2-3 aad3-3 lacks omega-7 fatty acids. Belongs to the fatty acid desaturase type 2 family. Extended N-terminus.