Date: 201408
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Flight plan: IFR
Mission: Passenger
Flight phase: Parked
Aircraft component: Fuel Tank
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Other / Unknown
Anomaly: Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural MEL / CDL; Ground Event / Encounter Other / Unknown
Detector: Person Ground Personnel
When detected: Aircraft In Service At Gate
Result: General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: While doing the preflight; I started the APU while the First Officer was loading the FMS. I noticed the X flow auto inhibit; which normally signals that the fueler is at the aircraft and beginning the process of fueling the aircraft. Shortly thereafter I noticed the odor of jet fuel. The ground support staff with some urgency requested the Captain out on the ramp. I went down to see what they needed. There was a fuel spill. The ramp worker initially indicated that the fuel came out of one of the left wing sump drains. The Ramper told me that it looked like three distinct bursts of fuel. I told the ground staff to back their equipment away from the area; I had the Fueler contact his company; and told the ramp staff to initiate the fuel spill procedures. I had the First Officer stop the APU; contact the company; and told the Gate Agent to stop the boarding process (no passengers were on the aircraft yet). The fueling company initiated a response at first with paper towel; and bundles of absorbent material. ARFF was notified and responded. I'm glad they were there. The fueling company brought over more absorbent material and the clean up crew was able to prevent the fuel from entering the airport storm water drainage system. The Fueler estimated 3 gallons; while the lead ARFF responder estimated 15 gallons. We needed to have a fuel load of 15;200 lbs; and only 14;500 (7;250 per wing; the wing tanks were almost full) was loaded before the spill event.  7;250 is when transfer from the center to the wing normally begins. After the clean up we were working with the Local Mechanic on how to make sure the aircraft was not going to jettison fuel during flight. Maintenance Control seemed very confused by the indications that were described to them. The Fueler told them that he was using manual mode; and that the left wing high level indicator was intermittently showing that it was on; even with no change in fuel level. Under the direction of Maintenance Control we added fuel to the center tank.  The Fueler and Mechanic set up a 55 gallon drum with the absorbent material and a ring or absorbent material under where the spill came from. The First Officer and I ran the engines to make sure that we were not going to be continuously jettisoning fuel. No abnormalities occurred. After much deliberation between the Mechanic and Maintenance Control MEL 28-25-04 was applied. This looks like a straightforward MEL; but how does the crew know the transfer SOV's are operative before starting the engines? Is the high level sensor used for fueling the same high level sensor used by the fuel computer to manage our fuel in flight? If I were to clarify this MEL I would specifically allow for pressure refueling in the non-affected tank; as well as the center tank. This MEL does not prohibit fuel in the center tank like many of the similar MEL's.  With a fuel spill there are many threats but the most pressing is the volatility of the fuel on the hot pavement; and the associated flammability of the fuel. Possible FOM and fuel SOP gap. The Fueler told me that in his manual the aircraft is not to be running; or starting while fueling is commencing. He said APU too; but our manuals make no reference to not starting the APU while fueling. Hot fueling with #2 running is a different story. Maybe he thought the APU was included in hot fueling. I'm not sure if when fueling in manual mode that the valves are supposed to work automatically; or not. In other words should the fuel system have prevented the fueler from putting 7;500 lbs in a 7;290 lbs container? Our OM lacks guidance on refueling aspects of the fuel system. Fueling in manual mode could be a threat. Especially if the valves must be closed when the tank is full. The crew does not know if the transfer SOVs are operative until the crew starts the engines; the MEL could use some additional language to help clarify.  I had the ground crew back the equipment away; but I should have had them push it awayso the exhaust would not ignite the fuel vapor. I think the company could clarify the MEL a bit; and add some more guidance in refueling procedures. I would recommend the company review the fuelers thought that the APU should not be started while fueling is in progress. If his manual is different than ours; then that should be addressed.  I think the crew and the airport personnel responded well to the spill. But the associated maintenance process to get the aircraft back on line seemed to be confused and haphazard. I thought about how I would know how much fuel is in the tank if the high level sensor is deferred; but then I realized that it wouldn't have spilled out if it wasn't full.




Synopsis: CRJ-700 Captain is informed of a fuel spill during fueling at the gate with fuel coming out of the wing tip vent. The problem is traced to the fuel high level sensor which is MEL'd. The Captain has many questions about how the system works and whether the MEL is adequate to prevent overflow in flight.