Boeing Co. plans to sell 80 airplanes directly to Iran Air in a deal worth up to $17.6 billion, the U.S. firm disclosed in a letter to two U.S. lawmakers.  The proposed sale includes: four Boeing 747-8 Intercontinental jumbo jets; 40 737 Max jets; 15 long-range 777-300ER jets; and 15 future-generation 777-9X aircraft.  Boeing would also help Iran Air lease an additional 29 new Boeing 737s.  The agreement has not been finalized and requires the approval of the U.S. government.