As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF AND GEAR SELECTED UP, MODERATE HAZE FILLED THE COCKPIT ALONG WITH A STRONG ODOR THAT SMELLED LIKE BURNING HYDRAULIC FLUID. AFTER LEVELING OFF THE HAZE AND ODOR DISSIPATED. AIRCRAFT RETURNED TO THE FIELD, AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE TROUBLESHOT AND FOUND HYD POWERPACK LEAKING AND FLUID COMING FROM THE HYD OVERFLOW DRAIN. REMOVED AND REPLACED THE POWERPACK, OPS AND LEAK CHECKED GOOD.