A gas turbine engine component includes a passage and a wall adjacent the passage. The wall includes a first side bordering the passage and a second side opposite the first side. The second side includes an array of cells. The wall also includes an array of channels. Each of the channels is located proximate a corresponding one of the cells. A coating is disposed over the cells. When the coating degrades the channels open to permit impingement air flow through the channel onto sidewalls of the cells.