Once aboard, he reported that the atmospheric pressure aboard the Constellation was at eleven pounds per square inch. Washburn, along with Montgomery Scott, Elliott, and Russ, went to main engineering to check if the ship's phaser banks had been fired.
Upon reaching engineering, Washburn, Elliott, and Russ ran a complete structural and control damage check, while Scott checked out the engines. Upon completion of the analysis, Washburn returned to auxiliary control to report the damage control party's findings to Scott and Kirk.
Later, when the Enterprise was attacked by the planet killer, the damage control party became stranded aboard the Constellation when the Enterprise's transporters went down. Washburn was originally requested by Scott to assist him in "coaxing" the impulse engines back into service to give the ship some maneuverability, but at the last minute he was snagged by Kirk to assist him with getting the viewing screen back into operation. After repairing the viewing screen, Kirk ordered Washburn to return to engineering to assist Scott in completing repairs he was originally asked by Scott to assist with.
Once repairs to the Enterprise's transporters were complete, Washburn, Russ, and Elliott returned to their ship, while Scott and Kirk stayed behind to rig the Constellation for destruction within the planet killer. (TOS: "The Doomsday Machine")