Propeller propulsion systems combined with Boundary layer ingestion (BLI) have been proposed as a propulsive system to reduce the CO2 emissions of aircraft by 50% by 2050. BLI leads to increased disturbances at the propeller disk and causes more noise due to the fluctuating blade loading. Using the APPU project as a test case, unsteady inflow is used to determine whether a metric to lower the blade loading fluctuation on an airfoil level is possible. Therefore, an optimisation was created using an Euler solver reliant on the harmonic balance method and the adjoint method to lower the computing time of the simulation. The combination of these methods has proven successful in turbomachinery applications. The optimisation scheme uses the modelled APPU inflow conditions to optimise for the drag coefficient while lowering the Root Mean Squared Error of the lift coefficient during the simulations by applying a constraint in various optimisation runs.