Abstract To study the influence of dynamic flight attitudes on the splash lubrication performance and churning power losses of the intermediate spiral bevel gearbox in a helicopter, a three-dimensional (3D) simulation model consisting of a spiral bevel gear pair, two bearing caps with oil guide holes and the housing is established, and CFD (Computational Fluid Dynamics) simulations with main flight attitudes are performed. The influences of turning directions, rotational speeds, circling attitude and accelerations on the distribution of lubricating oil, the flow rate of oil guide holes and churning power losses are discussed. A test rig for studying the splash lubrication performance of a gearbox under different dynamic attitudes is developed, and the feasibility of the present simulation method is validated by experiments.