SL 737-SL-49-084 HYDRAULIC LOCK IN APU SOLENOID VALVE. SERVICE LETTER RECOMMENDED MOS 06-APR-2012 SL 737-SL-49-085 LOW DUCT PRESSURE DUE TO APU INLET GUIDE VANE DISAGREES WITH COMMAND FAULT, SERVICE LETTER RECOMMENDED MOS 23-MAR-2012 SL 737-SL-49-086 APU OIL DRAIN TUBE MISALIGNMENT CAUSING EXTERNAL OIL