What was found
AC DEPARTED, DIVERTED, PILOT THOUGHT THAT HIS LANDING GEAR WAS NOT FULLY IN THE UP AND LOCK POSITION (UNKNOWN IF GEAR UNSAFE LIGHT WAS ON). PILOT SELECTED GEAR DOWN, NOTHING HAPPENED, PULLED EMERGENCY GEAR EXTENSION AND LANDED WITH NO FURTHER INCIDENT. MAINTENANCE INSPECTED SYSTEM AND FOUND THE HYDRAULIC POWER PACK TO HAVE FAILED. REPLACED POWER PACK. (SO05200506731)