Narrative:

While taxiing into position on [the] runway; another aircraft reported flames coming out of our number 1 engine. We taxied clear; shut down the engine; informed the flight attendants; and returned to the gate.

Google
 

Original NASA ASRS Text

Title: B737-700 Captain reported returning to the gate after another aircraft reported flames coming from the Number 1 engine during taxi.

Narrative: While taxiing into position on [the] runway; another aircraft reported flames coming out of our Number 1 engine. We taxied clear; shut down the engine; informed the Flight Attendants; and returned to the gate.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.