A gas turbine engine includes a fan section, an engine inlet, and a fan duct splitter in serial flow order. The fan duct splitter splits an airflow entering the engine inlet from the fan section into a fan duct and a core duct. The core duct includes a compressor section, a combustion section, and a turbine section in serial flow order. A duct assembly is coupled to the fan duct to extract a portion of a fan duct airflow passing through the fan duct and deliver the portion of the fan duct airflow to an active clearance control mechanism of the turbine section.