Date: 201503
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Light: Night
Aircraft: B737-800
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Aircraft component: Turbine Engine
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Fatigue; Distraction; Situational Awareness; Troubleshooting; Workload
Second reporter function: Pilot Not Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Flight Attendant; Person Passenger
When detected: Taxi
Result: Flight Crew Returned To Gate; Flight Crew Took Evasive Action; General Work Refused; General Maintenance Action
Contributing factors: Aircraft; Procedure; Human Factors
Primary problem: Procedure

Narrative: The aircraft had a fluid leak in the left engine behind the flame arrestor. It was an active leak several hours after the aircraft blocked in. Its surface measured approximately 14 X 8' and maintenance said it was oil. An oil accumulation is allowed in this area; so maintenance signed off the aircraft as airworthy and we left.Shortly after taxiing out of the ramp area; a Flight Attendant (FA) called and said the left engine has flames coming out of the back. We parked; [engaged] the brakes; shut down the engine; called ARFF; and ran the tailpipe fire checklist. I was in constant communication with the FA who had another FA monitoring the state of the left engine. The fire went out and stayed out. It was my judgment that the oil puddle ignited and starting the engine again would not be advisable. ARFF arrived soon after that and confirmed the engine was secure. We taxied to the gate with ARFF following and they checked the engine out again after the gate arrival and shut down. Throughout the event; I made PAs to reassure the passengers. I estimate I made PAs every 3-5 min. The feedback from the FAs later was that the passengers were thankful that I kept them informed and that we went back to the gate.On the jetbridge; I debriefed the fire chief; maintenance chief; ramp tower; and dispatcher verbally and answered all questions to their satisfaction.I don't recommend allowing such a large accumulation of oil in that place in the engine. Given the same circumstances; I think I would refuse the aircraft.


Second narrative: We had a maintenance issue at the gate due to an oil leak in the tail cone of Number 1 engine. It took a couple of hours to resolve the issue; ending with a quick engine run-up to insure everything was in order. We pushed off the gate and started engines. We were on taxiway G when we got a call from one of the flight attendants saying that the Number 1 engine was on fire. We came to a stop; shut the engine down; contacted ground control; and pulled out the QRH. Because we had no abnormal indications in the flight deck; and with the maintenance issue fresh on our mind; we referenced the Engine Tailpipe Fire Checklist.Ground Control sent the CFR. They came out; and checked us out. Everything was fine; so we taxied back in to a new gate. A new plane was assigned. Because of the late hour and lengthy delay (we would be landing at close to XA00); we ended up calling in fatigued.


Synopsis: While taxiing for takeoff; after Maintenance released the B737-800; a tailpipe fire developed apparently from an oil accumulation.