A PA28 pilot reported that his aircraft's engine and fuel tanks were removed for cleaning and inspection after Jet A fuel was accidentally mixed with 100LL at a refueling point on the previous flight.

Narrative

I stopped for fuel at a small Southern airport and the airport manager added 17.5 gallons to top the tanks. Total usable fuel capacity for this model is 50 gallons. I then proceeded north and made another fuel stop where the lineman added another 25.3 gallons. There were no obvious anomalies on this leg; which totaled 3.1 hours of flight time. However; the rate of climb seemed sluggish while departing from the second fuel stop; and once or twice I was aware of an unusual engine vibration. The next morning; I was contacted by the Airport Manager at yesterday's first fuel stop and advised that after my departure he'd learned that the delivery driver had mistakenly loaded about 5;000 gallons of Jet-A into the 100 low-lead tank at his fuel farm. My best estimate after the fact is that the fuel burned between the two fuel stops may have contained a concentration of Jet-A as high as 25%. Since I learned of the misfuelling; the airplane has been grounded and the engine removed for a tear-down inspection in accordance with Lycoming SB 398 B. The fuel tanks have been drained and removed for cleaning. Misfueling of the fuel farm itself is an exceptionally rare event. Perhaps redesigning fueling nozzles and tank ports to make it impossible to deliver the wrong fuel type would prevent a recurrence; but I'm not sure the industry would find it worth the cost.