Date: 202112
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: PC-12
Operating under: Part 91
Flight phase: Parked
Aircraft component: Fuel Drain
Component problem: Malfunctioning
Reporter function: Pilot Flying; Captain
Reporter qualification: Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Troubleshooting; Workload; Time Pressure; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Ground Event / Encounter Fuel Issue
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Maintenance Action; General Flight Cancelled / Delayed
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: During pre-flight I attempted to sump the fuel in accordance with the Pilatus POH.  The first point I tested was the outer sump on the left wing.  I used the fuel tester to open the valve and then released the valve once I had an adequate fuel sample.  The sump valve closed; but fuel continued to leak out.  I attempted to reseat the valve by opening and then closing it again; but fuel continued to leak out.  I then attempted to mitigate fuel being spilled on the ground using the fuel tester cup and a bucket and absorbent pads provided by the FBO.  I also contacted our company maintenance department who then dispatched a local vendor to come out and look at the problem.  While I waited for the maintenance provider to arrive; I attempted to use my body to block the wind that was blowing the fuel stream around.  When the mechanic arrived; he also attempted to reseat the valve but with no success.  He stated the valve would have to be replaced and that would require draining the tank.  I also informed [the flight department] of the situation and the flights were moved to a different tail number.  I then wrote up the aircraft per our company's maintenance departments instructions.The fuel sump seals are a recurring problem with this aircraft that I believe need to be addressed with Pilatus.  Pilatus states that the tanks need to be check for fuel contamination; but when you actually follow their guidance; a leaking fuel sump is often the result.  This sometimes cannot be remedied quickly; requiring costly de-fueling as well a disruption to the flight schedule as happened today.  I had just topped off for the day with almost $1;000 in fuel that the company will now have to eat the cost of!  More importantly; however; there is a safety culture problem that this recurring problem presents as well because it encourages pilots not to sump the tanks at all because of the possibility of a leak occurring.  I have heard senior captains and even instructors actively discourage other pilots from checking for fuel contamination to save the hassle of a stuck valve.  If Pilatus expects us to sump the tanks; then the valves and seals need to be up to the job.  This aircraft is only 3 years old!Left wing outer fuel sump leaking after I attempted to test the fuel.




Synopsis: PC-12 Captain reported draining a small amount of fuel from the tank; to check for contamination; only to find the sump valve was stuck open. Maintenance was contacted but the leak could not be stopped and the flight was canceled. The Captain stated this is a common occurrence with this Pilatus aircraft.