Boeing Co 747-438, VH-OJN

Shortly after take-off, the crew of the Boeing 747 aircraft
received a number-four engine fire warning advisory. The crew
actioned the non-normal checklist, secured the number-four engine,
and discharged two engine fire bottles before the fire indication
extinguished. The crew then jettisoned fuel and completed an
uneventful landing at the departure airport.

Initial inspection by operator maintenance personnel revealed
evidence of charring and discolouration around the engine
combustion area. Maintenance personnel removed the engine from the
aircraft and the engine was then test run on an engine test cell.
The test run revealed a fuel leak from the left and right fuel
manifold connectors. The connectors were confirmed as being secured
with safety lockwire, but subsequent torque checks revealed a lower
value of torque than that required by the engine manufacturer's
maintenance manual. The fuel manifold connectors were re-torqued
and another test run completed. The resulting test run at high
power settings revealed no discrepancy. A decision was made by the
operator to have the engine overhauled before being put back into
service.