Usina Santa Lydia Airport (ICAO: SDUL) is a small private airfield located near Ribeirão Preto in the state of São Paulo, Brazil. It serves the operational needs of the Usina Santa Lydia sugar and ethanol production facility, one of the agricultural enterprises in the region. The airfield is not open to scheduled commercial traffic and functions primarily as a general aviation and corporate aviation facility supporting the agricultural operations of the associated sugar mill. Ribeirão Preto itself is a major agribusiness hub in Brazil's interior, and private airstrips serving large agricultural enterprises are common in the area.