ahead of her at 12:49 at a range of , I-11 fired four torpedoes, dived to , and rigged for silent running. At 12:51, Hornet sighted a torpedo wake off her starboard quarter, and the pilot of a TBF-1 Avenger torpedo bomber patrolling overhead saw what he identified as the conning tower of a submarine breaking the surface between North Carolina and a destroyer on plane guard duty. The Avenger pilot dropped a depth charge on what he thought was a conning tower; its explosion detonated two of I-11′s incoming torpedoes, and I-11′s crew heard two large explosions at 12:52. Hornet began a hard turn to port, while North Carolina turned to starboard. One torpedo passed off North Carolina′s port side. The task force's escorts began searching for I-11, and at 14:52 the destroyer gained contact on her and dropped six depth charges. At 15:13, Russell′s lookouts sighted an oil slick long by 0.5 nautical mile (0.9 km; 0.6 mi) wide, but Russell lost contact with I-11 at a range of . When Russell regained contact, I-11, operating at a depth of , made a late detection of the approaching destroyer and commenced a dive to . Russell′s subsequent depth-charge attack resulted in a number of explosions close aboard that caused a minor leak at I-11′s stern through her propeller shaft gland, temporarily disabled her sound gear, and wrecked 80 per cent of her batteries. The battery damage and leak caused her forward compartments to fill with poisonous chlorine gas. I-11 reached a depth of before her crew could regain control of her. I-11′s crew put on gas masks and rewired the intact batteries to partially restore electrical power. During the evening of 6 September 1942, seven hours after the depth-charge attack, I-11 surfaced. Her crew assessed that they could repair the leak, but determined that I-11 could not dive, so she made for Truk on the surface at best possible speed. On 7 September 1942, a U.S. Navy PBY-5 Catalina flying boat of Patrol Squadron 11 (VP-11) attacked her northeast of Santa Isabel Island at ; while I-11′s crew fired at the PBY with her deck gun and her four 25 mm antiaircraft guns, along with three Type 38 carbines and her floatplane′s 7.7 mm (0.303 in) Type 92 machine gun, which they had lashed to her bridge railing, the PBY dropped three bombs, one of which landed close