Disclosed is a flutter damper, including an acoustic liner in fluid communication with a fluid flow the acoustic liner being configured for peak acoustical energy absorption at a frequency range greater than a frequency range associated with fan flutter, and a plurality of modular chambers configured for peak acoustical energy absorption at a frequency range associated with one or more fan flutter modes, the plurality of modular chambers disposed radially outside the acoustic liner, the plurality of modular chambers including a circumferential gap between proximate circumferential ends of at least one adjacent pair of modular chambers, and the plurality of modular chambers each including a plurality of circumferentially aligned and connected chamber segments, and wherein at least one of the chambers in the plurality of modular chambers has a mutually unique length, width and/or height or shape.