CREATE TABLE table_659 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "U.S. viewers  ( million ) " CLOB)

When did the episode 'Hell bent for leather' originally air?
SELECT "Original air date" FROM table_659 WHERE "Title" = 'Hell Bent for Leather'
SELECT "Original air date" FROM "table_659" WHERE "Title" = 'Hell Bent for Leather'