Date: 201810
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: IMC
Weather elements / visibility: Rain; 10
Light: Daylight
Aircraft: PC-12
Operator: Corporate
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Initial Climb
Airspace: Class B DAL
ATC / advisory: Tower ZZZ
Aircraft component: Propeller Assembly
Component problem: Malfunctioning
Reporter organization: Corporate
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Instrument
Anomaly: Aircraft Equipment Problem Critical
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Flight Crew Returned To Departure Airport; Flight Crew Landed in Emergency Condition; General Flight Cancelled / Delayed
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: Two crew; two passengers. There was drizzle on the field at the time of departure. Pockets of rain showers were west and north of Dallas. On departure one cell was located over the downtown area. On a normal departure I was given a climb to 3;000 feet and runway heading. We took off and cleaned up the aircraft normally. We first noticed a film developing on the windshield at about 800 feet. I was trying to understand if the film was due to the drizzle conditions or if there was oil or grease on the windshield. I was given a frequency change to departure. I switched frequencies and I discussed the situation. Checked windshield heats; checked oil temperature and pressure. By this time we were climbing through 2;000 feet. The windshield was now completely covered in film. At this point we decided to return to land.I called Departure Control and stated that we would like to return to land. There was no response from Departure so I called again. Still nothing so I checked the frequencies which appeared to be operational. As we leveled off at 3;000 feet. I switched back to Tower and told them that we needed to return for an immediate landing. I did not get an immediate response. At this time we decided to [advise ATC]; stated our intentions of landing; and started a left turn back to the airport and reduced power to a minimum setting. Tower then instructed us to enter left downwind. Tower asked our intentions and I replied we would be making a precautionary landing. We were cleared to descend at our discretion. I then briefed the passengers that we were returning to land and that we would be making a precautionary landing. After our turn toward the field we were confident it was oil leaking on the windshield. We noticed a faint smell in the cockpit. I monitored oil pressure and temperature as we approached the airport. We discussed requesting a landing on the opposite runway as we were concerned of a potential engine failure. I asked Tower if it was available. By the time they responded we were in a position to glide to our original runway if necessary so we continued on downwind at 2;500 feet. Tower gave us a traffic advisory that I acknowledged. We kept a tight base leg to remain within gliding distance and made an uneventful landing despite having restricted forward visibility through the windshield. We exited the runway and Tower instructed us to inform ground of any services we would need. We decided to taxi back to parking. Ground Control gave us progressive instructions and we shutdown without incident. Post flight inspection revealed the propeller shaft seal was leaking internally and externally. Oil was sprayed inside and outside the engine cowling. Externally it ran down 3/4th the length of the fuselage. The top of the nose and windshield were covered. The oil level was at the bottom of the normal range on the sight gauge. Comparing to where the oil level was on preflight we appeared to lose 1 qt of oil. The flight was 0.1 hours on our hobbs meter. It was the 5th flight and 7.2 hours after the annual inspection had been performed. The propeller had been removed to replace a seal during that annual inspection.




Synopsis: PC-12 pilot reported an oil leak causing limited forward visibility and a return to the departure airport.