Date: 201710
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: EMB ERJ 145 ER/LR
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Fuel Distribution System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Distraction; Troubleshooting; Workload
Anomaly: Aircraft Equipment Problem Less Severe; Ground Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: At the gate in ZZZ; during the boarding process; we were receiving our fuel for the flight. We had a large fuel spill at the gate due to some issue with the fuel truck; or the aircraft; which directed fuel into the left wing fuel tank only briefly; and then solely into the right wing fuel tank until full and then overflowing onto the ground under the outboard span of the wing. Fuel covered the concrete surface and also went into storm-type drains embedded into the concrete under the wing of the aircraft. Our first indication of an issue was an 800 pound fuel imbalance which triggered an EICAS caution message. I do not know the underlying cause of this incident.Earlier; we had started the APU pulling into the gate at ZZZ; anticipating a very quick turn due to previous delays. The parking flow and checklist has the #2 fuel pump ON to supply the APU; and the #1 fuel pump off; unless cross-feeding fuel to the APU; which was not the case today. This is a normal condition for line operations; and very often; aircraft are fueled with the APU running and the pumps in this configuration. I was asked whether I had turned ON or OFF fuel pumps during fueling; by ground personnel; but the pumps were configured by muscle memory (cockpit flow procedure prescribed by the Aircraft Operations Manual 1) and verified with a checklist upon engine shutdown; well before being fueled. The pump switches were not touched after the chocks were installed.The First Officer stated to me that the fueler; when asked to stop fueling; released the rope which holds open the valve on the truck; and awaited further instructions. For some reason the fuel flow did not stop coming out of the truck; whether by mechanical discrepancy in the truck; aircraft; or the physical properties of motive flow of liquids. Immediately; the First Officer ran outside to tell the fueler to stop fueling. Fuel tank 1 was at 2400 lbs consistently at this point; and tank 2 was at about 4000 lbs; and increasing by the time the First Officer returned. The First Officer came back into the flight deck stating that the fueler said he would stop fueling.We both noticed that the number 2 fuel tank (only the number 2) was still filling rapidly. The First Officer ran back outside to notify the fueler about this; and then ran back inside the flight deck to report that the fuel tank was spilling fuel at a high volume and rate; and that even though the fueler said he had stopped; the fuel was still flowing out of the truck into the aircraft. The #2 tank had been over-filled; and it dumped fuel until the fuel truck actually stopped pumping fuel. By planned calculation; we would have had a total of 2700 lbs of fuel on the aircraft (balanced between both tanks) upon arrival at the gate. When I shut the aircraft down for the gate-evacuation; the aircraft had approximately 2400 lbs of fuel in the left tank; and an over-filled right tank around 5600 lbs.The First Officer conferred with me and executed an evacuation into the jet bridge for passenger safety. I completed the emergency evacuation QRH procedure; shutting down the aircraft APU and electrical system; but in my judgment; not pulling the fire handles (to avoid an inadvertent discharge of the fire retardant into the engines.) The First Officer called ZZZ ground control to report the fuel spill on the aircraft's comm radio; and then went outside the aircraft to initiate some sort of containment and address any issues with personnel below the wing. I ushered the passengers towards the gate area for their safety and verified the aircraft and jet bridge were both vacant before meeting with the fire chief on the ramp area in front of the right wing. I notified dispatch when I was able; and answered questions for the dispatch supervisor. We were given the all-clear by the fire chief to unload bags so that we could keep our operation moving. While in conversation with the fire chief; a pump and hose were being used by (I believe) the fuelcompany to remove fuel from the storm drain which was located below the right wing of our aircraft at the gate in ZZZ.In all; we estimated a spill of up to 250 gallons of Jet A. When all statements were made and recorded; I retrieved the aircraft log and entered three discrepancies. The first was that the aircraft single point refueling system (SPR) seemed to not accept fuel into the left wing fuel tank. The second write-up was that the aircraft's right fuel tank was over-serviced resulting in a fuel leak. The last write up was that the aircraft had a 3000 lb fuel imbalance and must not be moved.




Synopsis: EMB145 Captain reported a significant fuel spill while fueling was in progress at the gate. The aircraft was safely evacuated and the spill was addressed by ground personnel.