The proposal is to measure the inelastic scattering from a single crystal of Åkermanite on cooling towards and through the incommensurate phase transition at 358 K. There are two main objectives. First is to identify the phonon mechanism responsible for the phase transition through a detailed characterisation of the phonon dispersion curves across the Brillouin zone, and to determine its temperature dependence. Using our new methods we will fit a force constant model to the complete 4-dimensional dataset. The second objective is to obtain data to support our work in developing methods for the analysis of four-dimensional inelastic scattering measurements obtained on Merlin; these methods will also be applicable to LET.