Date: 201204
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: B737-400
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Taxi
ATC / advisory: Ground ZZZ
Aircraft component: Exhaust Gas Temperature Indicat
Component problem: Failed
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Troubleshooting; Time Pressure; Communication Breakdown; Training / Qualification
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Detector: Person Ground Personnel
When detected: Taxi
Result: Flight Crew Returned To Gate; Flight Crew Took Evasive Action; General Declared Emergency; General Maintenance Action
Contributing factors: Aircraft; Human Factors
Primary problem: Aircraft

Narrative: During engine start; number two engine N2 gauge failed just as start lever selected to idle. Engine failed to start. N2 indicator showed zero with no digital display. Contacted Maintenance Control and discussed the maintenance issues and agreed to return to gate; contract Maintenance MEL'ed the N2 gauge per Maintenance Control. After thoroughly reviewing the MEL procedure for engine start both engines started normally with stable engine indications. Just as we getting ready to taxi Ground Control advised us that Operations called them to advised us that the #2 engine was on fire. I asked the Controller if he could visually confirm. He said he could not see that side of the aircraft. At this time we had no cockpit fire warning indications. I placed the start lever to cut off; requested Crash Fire Rescue to inspect the engine and aircraft. I also requested the B Flight Attendant to visually check the right engine. Both the Flight Attendant and the fire crew reported no sign of smoke or fire. We completed the QRH Engine fire/severe damage check list pulling the right fire handle but did not discharge fire bottles. After stabilizing the situation we returned to gate and contacted Maintenance Control and the Dispatcher. Note; prior to starting the #2 engine; we motored the engine 60 seconds to ensure any residual fuel and vapors were purged. What was reported to the Ground Controller as an engine fire from our operations was probably a tail pipe torching. Because the MEL start procedure was somewhat complicated I chose to finish the pushback and then start; so I was not in contact with the push crew during engine start. During this entire event a FAA Safety Inspector occupied the cockpit jump seat. It may have been misidentified as an engine fire rather than a tailpipe torching.


Second narrative: The N2 gauge was MEL'd as well as the Engine Start switch. The Captain talked to Maintenance twice and the Contract Mechanic onsite regarding the fact that the engine wasn't motored after the previous start. They both said that on the next start motoring the engine for 60 seconds prior to start would be sufficient. We pushed back and complied with the MEL's and started the No.1 engine first then the No.2 engine. We motored the engine for 60 to 65 seconds prior to introducing fuel. The EGT was around 550 on the start. Then the Ground Control said our right engine was on fire.


Synopsis: A B737-400 N2 gauge failed during start which caused a starter disconnect; so the crew did not motor to clear fuel. After the MEL was completed; on start a tailpipe fire ignited which the ground crew reported as an engine fire so emergency equipment was dispatched.