170404-N-RC734-117 PACIFIC OCEAN (April 4, 2017) Airman Aaron Guillory, right, and Aviation Boatswain�s Mate Airman Anthony Similton attach tie down chains to an AH-1Z Viper Attack helicopter assigned to Marine Medium Tiltrotor Squadron (VMM) 161 aboard the amphibious transport dock ship USS San Diego (LPD 22). (U.S. Navy photo by Mass Communication Specialist 1st Class Joseph M. Buliavac/Released)