As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFTS LEFT MAIN LANDING GEAR WOULD NOT RETRACT ON CLIMB-OUT. THE MAIN GEARS WAS THEN HAND PUMPED DOWN UNTIL THREE GREENS WERE INDICATED. RETURNED TO FIELD WITH NO FURTHER INCIDENT. MAINTENANCE FOR AIR MIDWEST REMOVED AND REPLACED THE HYDRAULIC POWER PACK FOR CORRECTIVE ACTIVE. (M)