A heat shield for a combustor of a gas turbine engine has a heat shield adapted to be mounted to a combustor wall with a back face of the heat shield in spaced-apart facing relationship with an inner surface of the combustor wall to define an air gap. Rails extend from the back face of the heat shield across the air gap. Grooves are defined in at least one of the rails. The rail grooves are in fluid flow communication with the air gap when the heat shield is mounted to the combustor wall.
