What was found
21-10 A RAPID DECOMPRESSION OCCURRED AT 13000' ON DEPARTURE FROM SINGAPORE, DURING LEVEL FLIGHT. AN EMERGENCY DECENT WAS CARRIED OUT AND THE QRH CHECKLIST FOLLOWED. THE AIRCRAFT WAS FLOWN SAFELY BACK TO WSSL. COMPLIED WITH LEFT MAIN LANDING GEAR GROUND CONTACT SWITCH - REMOVAL/ INSTALLATION IAW G100 SPX AMM 32-60-01 REV 26 NOV 15/24 FOUND SATISFACTORY. PERFORMED MAIN LANDING GEAR GROUND CONTACT SWITCH ADJUSTMENT/ TEST IAW G100 SPX AMM 32-60-01 REV 26 NOV 15/24 FOUND SATISFACTORY. PERFORMED POSITION AND WARNING SYSTEM OPERATION TEST IAW G100 SPX AMM 32-6-00 FOUND SATISFACTORY. PERFORMED CABIN PRESSURE CONTROL SYSTEM OPERATIONAL TEST (DURING LEFT ENGINE RUN -UP) IAW G100 SPX AMM 21 -30-00 FOUND SATISFACTORY. LEFT MAIN LANDING GEAR GROUND CONTACT SWITCH PN OFF: 444EN1 -6, SN OFF: N/A, PN ON: 444EN1 -6 SN ON: N/A.