The controller and myself both at the same time advised on the tower frequency that the the engine maybe on fire,
This was to advise the pilot of a visual state of the engine, no doubt he had alarms and bells going off in the cockpit anyway,
pls just report what you see and not what you think might be happening.
no lights and bells for a surging engine. just shut it down. but if some one reports the engine on fire[it wasn't] the crew is pretty much forced to put a fire bottle in.
flames from the front or back is not the same as an engine fire.