Delta Air Lines flight DL55 returned to land at Lagos-Murtala Muhammed International Airport in Nigeria after an engine fire indication on takeoff. The aircraft, an Airbus A330-223, took off from runway 18R at 22:52 hours. When the aircraft was climbing out of 1700ft AMSL, the no. 1 engine fire warning came ON. A few seconds later, the crew declared an emergency and requested an immediate return which was approved by ATC. The aircraft landed at about 22:59 and stopped on runway 18R. The Airport Rescue and Fire Fighting Services (ARFFS) reported observing fire on engine no.1 and extinguished it. Passengers were evacuated using the emergency slides on the right side of the aircraft. One passenger sustained serious injuries while 11 suffered minor injuries. Causal Factor An overtemperature condition and localized fire within the No. 1 engine cowling triggered a fire warning. The overtemperature and fire were caused by the ignition of fuel from a hairline crack on the fuel manifold supplying fuel nozzle 1. Contributory factor The fuel manifold cracking can be attributed to high vibratory stresses due to coupling of an acoustic combustor mode and a fuel manifold structural mode. Note: AIB Nigeria rated the occurence a ‘Serious Incident’. However, as per ICAO Annex 13, this event was an Accident as one occupant had suffered serious injuries.