A Canadair water-dropping plane sank off the isle of Patroklos, south of Attica, yesterday after it was hit by a massive wave as it was refilling its tanks while helping fight a fire. The two pilots, who were not hurt, evacuated the plane as it was sinking. The CL-125 plane sank at about 9.40 a.m., authorities said. It was involved in efforts to put out a fire on the island of Kea, off the Attica coast. A Super Puma helicopter picked up the two men from the site of the incident under difficult weather conditions, seamen said. Two frigates tried to tow the plane to safety but failed because the aircraft had taken in a lot of water. Even if the plane is pulled out of the water, it may not be usable, authorities said.