What happened
On March 12, 2001, a Boeing 747-400, registered as ZS-SAZ, was operating an international scheduled flight from Johannesburg International Airport to Heathrow International Airport. During the flight, the cockpit crew received an Engine Indication and Crew Alerting System (EICAS) status message indicating a fuel imbalance involving the number 4 engine. In response to the alert, the crew shut down the affected engine. The aircraft subsequently diverted to Barcelona Airport, where it landed safely. There were no fatalities and no injuries reported among the passengers or crew.
The investigation
Following the diversion, a ground engineer from Heathrow arrived at Barcelona to perform a detailed inspection of the number 4 engine. The physical examination identified that the fuel line, positioned between the fuel filter and the engine-driven fuel pump, had been chafed through. This degradation resulted in an excessive leakage of fuel. Once the damaged fuel line was replaced, subsequent checks confirmed that the leak had been resolved.
Findings
- The primary cause of the fuel imbalance was a chafed fuel line located between the engine-driven fuel pump and the fuel filter.
- The investigation noted that this specific issue had been reported by other operators, with instances of chafing severe enough to cause significant damage.
Safety action
In response to the incident, a one-time inspection of the relevant fuel lines was conducted across the South African Airways fleet, and securing clips were replaced where necessary. Furthermore, Service Bulletin No 73-9841 was issued to replace the existing securing clips with a more robust design. South African Airways has since retrofitted all applicable fuel lines on their Rolls Royce engines with these improved clips.