SA Airlink RJ85 near Johannesburg on Jun 25th 2013, engine fire warning

A SA Airlink Avro RJ-85 on behalf of South African Airways, registration ZS-ASW performing flight 4Z-8739/SA-8739 from Johannesburg to Pietermaritzburg (South Africa) with 44 passengers and 4 crew, was enroute about half way into the journey when the crew received a fire warning for engine #4 (LF507, outboard right hand), actioned the relevant checklists shutting the engine down and discharging the fire suppression system. The crew turned the aircraft around and returned to Johannesburg for a safe landing.

The incident aircraft resumed service on Jun 27th.

South Africa's CAA reported the aircraft experienced a #4 engine warning +/- 80nm from Pietermaritzburg, the crew actioned the relevant QRH and returned to Johannesburg declaring a phase 1 emergency (lowest level of three).

In 2014 South Africa's CAA (SACAA) released their final report concluding the probable cause of the incident was:

The fire warning was most probably activated by the passing of high-pressure fuel, as the fuel nozzle and associated gasket were found to be loose after the aircraft landed.

The SACAA reported that following the flight maintenance found minor scorch marks on engine #4. Further examination identified a loose fuel nozzle, the gasket of which had been damaged by fuel passing at high pressure.

The scorched fuel nozzle (Photo: SACAA):