A thrust reverser synchronization shaft lock system comprising: a rotatable shaft comprising at least one radial prong extending radially from the shaft; a hydraulic lock assembly comprising a housing comprising a tubular inner wall defining a chamber, a piston head configured to contact the tubular inner wall and comprising a first piston face on a first longitudinal side of the piston head, a second piston face on a second longitudinal side of the piston head opposite the first piston face, and a lock recess, and configured to divide the chamber into a first fluid chamber defined by the tubular inner wall and the first piston face, and a second fluid chamber defined by the tubular inner wall and the second piston face, a piston rod, extending radially away from the shaft from a first piston rod end to a second piston rod end opposite the first piston rod end, and configured to be urged by the piston head to move the first piston rod end out of engagement with the radial prong to selectably permit rotation of the shaft, and a bias member (660, 662) configured to urge the first piston rod end into engagement with the radial prong to selectably prohibit rotation of the shaft; and an electric lock assembly comprising a lock pin, and an electric actuator configured to controllably extend and retract the lock pin in and out of engagement with the lock recess to selectably prohibit and permit movement of the piston rod. a rotatable shaft comprising at least one radial prong extending radially from the shaft; a hydraulic lock assembly comprising a housing comprising a tubular inner wall defining a chamber, a piston head configured to contact the tubular inner wall and comprising a first piston face on a first longitudinal side of the piston head, a second piston face on a second longitudinal side of the piston head opposite the first piston face, and a lock recess, and configured to divide the chamber into a first fluid chamber defined by the tubular inner wall and the first piston face, and a second fluid chamber defined by the tubular inner wall and the second piston face, a piston rod, extending radially away from the shaft from a first piston rod end to a second piston rod end opposite the first piston rod end, and configured to be urged by the piston head to move the first piston rod end out of engagement with the radial prong to selectably permit rotation of the shaft, and a bias member (660, 662) configured to urge the first piston rod end into engagement with the radial prong to selectably prohibit rotation of the shaft; and a housing comprising a tubular inner wall defining a chamber, a piston head configured to contact the tubular inner wall and comprising a first piston face on a first longitudinal side of the piston head, a second piston face on a second longitudinal side of the piston head opposite the first piston face, and a lock recess, and configured to divide the chamber into a first fluid chamber defined by the tubular inner wall and the first piston face, and a second fluid chamber defined by the tubular inner wall and the second piston face, a piston rod, extending radially away from the shaft from a first piston rod end to a second piston rod end opposite the first piston rod end, and configured to be urged by the piston head to move the first piston rod end out of engagement with the radial prong to selectably permit rotation of the shaft, and a bias member (660, 662) configured to urge the first piston rod end into engagement with the radial prong to selectably prohibit rotation of the shaft; and an electric lock assembly comprising a lock pin, and an electric actuator configured to controllably extend and retract the lock pin in and out of engagement with the lock recess to selectably prohibit and permit movement of the piston rod. a lock pin, and an electric actuator configured to controllably extend and retract the lock pin in and out of engagement with the lock recess to selectably prohibit and permit movement of the piston rod.