The subject matter of this specification can be embodied in, among other things, a rotary lock assembly that includes a first epicyclic gear assembly having a first sun gear assembly, a first ring gear assembly, and a first planet gear assembly mechanically engaged to the first sun gear assembly and the first ring gear assembly, and a second epicyclic gear assembly having a second sun gear assembly configured to be rotated by the first ring gear assembly, a second ring gear assembly, and a second planet gear assembly mechanically engaged to the second sun gear assembly and the second ring gear assembly.