"Petrel" departed New London on 6 January 1966 for Holy Loch, Scotland, with in tow. On 17 January, an Air Force B-52, carrying four unarmed Mk.28 nuclear bombs, collided with a KC-135 off Palomares, Spain. "Petrel" was sent to the area to aid in salvage operations and had the delicate task of maintaining position over the bomb. The weapon was brought to the surface on 7 April, by the ROV "CURV", placed on "Petrel", and transferred to the . "Petrel" then returned to Charleston.