LETTER MOS 07-JUL-2009 SL 737-SL-29-108 REV. 8 HYDRAULIC PRESSURE MODULE CARTRIDGE CHECK VALVE FRACTURES. SERVICE LETTER INFORMATIONAL MOS IS-MAR-2010 SL 737-SL-29-108 REV. C HYDRAULIC PRESSURE MODULE CARTRIDGE CHECK VALVE FRACTURES (SUPERSEDED BY SL 737-SL-29-108 REV. SUPERSEDED 0). SERVICE LET