A gas turbine engine airfoil includes first and second sidewalls joined together at opposite leading and trailing edges, and extending longitudinally from a root to a tip. The sidewalls are spaced apart from each other to define in part first and second adjoining flow chambers extending longitudinally therein, and defined in additional part by corresponding first and second partitions disposed between the sidewalls. The second partition is common to both chambers, and both partitions include respective pluralities of first and second inlet holes sized to meter cooling air therethrough in series between the chambers.