LETTER MOS 30-SEP-2004 SL 737-SL-21-064 OUTFLOW VALVE SOFTWARE UPGRADE AND EMI ENHANCEMENT. SERVICE LETTER MOS 04-NOV-2004 SL 737-SL-21-065 AIR CONDITIONING FLEX HOSE SEPARATION AT THE OVERHEAD DISTRIBUTION TAPED JOINTS. SERVICE LETTER MOS 15-K4AR-2005 SL 737-SL-21-065 REV. A AIR CONDITIONING FLEX HOSE SEPARAT