What was found
HYD VOLUME LOW CAS MESSAGE DURING FLIGHT. RAN QRH, UNLOADED HYDRAULICS, USED LANDING GEAR BLOWDOWN, AND PULLED EMERGENCY BRAKING HANDLE TO STOP AIRCRAFT ON RUNWAY. CORRECTIVE ACTION: RESET PNEUMATIC OVERRIDE ON THE LANDING GEAR MANIFOLD AND RESET THE EMERGENCY GEAR EXTENSION SYSTEM REFERENCE TO CESSNA 680A AMM 32-34-00. REMOVED LH ENGINE DRIVEN HYDRAULIC PUMP (PN- 9914643-3, SN-K0709). INSTALLED CUSTOMER SUPPLIED OVERHAULED HYDRAULIC PUMP (PN- 9914643-3, SN 2497B). OPERATIONAL AND LEAK CHECKS ARE GOOD IN REF TO CE680A MM 29-10-05.