ta Sheet Al2EA. REFER TO: GULFSTREAM AEROSPACE CORP. (GAC] MAINTENANCE MANUAL, ILLUSTRATED PARTS LIST, AND WIRING DIAGRAM MADATAL - ATA CHAPTER 49; GARRETT AIRESEARCH AUXILIARY POWER UNIT MAINTENANCE MANUAL 49-21-89 FOR MODEL GTCP36-1CCG; GREYHOUND CORP. API SURGE VALVE CONTROL MODIFICATION ELECTRICAL CHG. No. 4