I'd like to nominate the previous USS Porter to the one already nominated. This one was DD-355 named for David D Porter and was sunk during the Battle of Santa Cruz Islands. http://navalmerchantshiparticles.blogspot.com/2010/01/fight-of-uss-smith-dd-378.html
The USS Porter (DD-356) had just rescued the crew of a ditched TBF Avenger when a sailor on the destroyer spotted an incoming torpedo just before it slammed into the vessel amidships and exploded. The task force immediately assumed a Japanese submarine had launched the fish, but the destroyer was actually the victim of the downed Avenger. The TBF had been unable to jettison its torpedo, which came loose and began running when the plane hit the water. The Porter's surviving crewmen, as well as the rescued airmen, were taken aboard the Shaw (DD-373), which later sank the crippled Porter with gunfire.http://www.usni.org/magazines/navalhistory/2007-12/contact
A Mr. Sawruk responds: "From U.S. Navy official reports, an enemy submarine torpedo is suspected but so is a torpedo from a ditched Avenger. The enemy weapon was accepted at the time, and that brought an end to the matter.
I reviewed the deck logs for all of the vessels present at the time and the Porter's log (which has survived) shows that the torpedo struck about two minutes after the TBF ditched. In addition, the destroyer logs report no loss of a torpedo from any of them and no U.S. subs were in the area.
A VF-10 pilot made a great report about this incident, as he had a birds-eye view of the situation. After the Porter stopped to pickup the ditched crew, he saw an erratic torpedo circling, which then straightened out and hit the Porter. He tried to strafe it to get it to explode but U.S. antiaircraft fire drove him off. There was only one torpedo. Some on board ship thought there were two torpedoes but the circling probably accounts for this.
I had contact with the ditched VT-10 pilot. When I told him what I believed had happened, he was upset but had suspected all along that this is what really happened. In his defense (not that he needs any), his plane had been badly damaged by a Zuiho A6M enroute to the target and on fire. He had to abort his mission. He considered bailing out with his crew but was able to get the fire out. He tried to get rid of the torpedo, both electrically and manually, without success. Because of this, it almost certainly was lying against the bomb bay doors. The ditching was successful, and the crew had sufficient time to get themselves and the raft out of the aircraft before it sank. The torpedo struck while they were climbing on board the Porter."
A very unlucky Good Samaritan!
All the best