Dash 8-300
Flight Crew Last 90 Days 200; Flight Crew Total 12000; Flight Crew Type 11000
Troubleshooting
Aircraft Equipment Problem Critical; Inflight Event / Encounter Fuel Issue
Flight Crew Landed As Precaution; Flight Crew Returned To Departure Airport; General Declared Emergency; General Maintenance Action
Aircraft
While the First Officer was completing the After Takeoff Checklist. I noticed that even though the AUX fuel pumps were selected off; the light for the left (Number 1 pump) was still illuminated. I touched the switch to confirm it was off and the light stayed on. I noticed we had approximately 200 LBS fuel imbalance at this time. My initial thought was the pump was transferring fuel of its own accord; then; I remembered I had read through the yellow pages in the maintenance log and was aware that a history [of fuel venting from the NACA vent] had started with the same situation. I looked out my window to see a vapor trail of fuel coming from the left NACA vent. I discussed a precautionary engine shut down with the First Officer. We both felt with the mechanical history it was probably not warranted. I transferred control of the aircraft to the First Officer; called the Flight Attendant and asked him to check the cabin for any fuel odor (there was none); then called Maintenance Control on the SAT phone to confer regarding past maintenance history and a possible precautionary shutdown. Maintenance also felt shutdown was not warranted. I came back heads up in the cockpit and resumed control as the pilot flying. We informed ZZZ Approach we would be returning to the field and asked for the trucks to be on hand to check the left side of the aircraft/engine after landing. We returned expeditiously for a normal landing on Runway XX; cleared on B then turned on M taxiway. We stopped the aircraft and shut down the number 1 engine while fire personnel checked for any evidence of leaking fuel; none was found. We taxied to the gate followed by the trucks. After further checks of the left side engine and wing area; we deplaned normally.
A Dash 8-300 flight crew returned to their departure airport when they noted a chronic fuel venting problem was recurring.