On 21 September 2012 a fire occurred in the engine compartment of a Mercedes Benz bus, model 0405NH.

The bus was inspected by two independent fire investigation experts who found two possible causes: A pair of brackets designed to stabilise the exhaust manifold and turbocharger failed.

The resulting excessive movement of the brackets caused (abrasion and) perforation of the fuel return hose. Diesel was sprayed onto the exhaust manifold and turbocharger exhaust housing as a result. The electrical wiring loom routed over the top of the engine near the fuel pump made contact with an angled steel bracket. The protective insulation became worn causing a short circuit which ignited accumulated oily matter.

Operators of this model bus should consider inspecting their buses and updating their inspection checklist to include these two areas. The wiring loom discussed in point 2 above can be viewed by opening the internal rear floor cover to the engine compartment.

For further information about this matter and/or bus legislative requirements in Victoria, please contact Andrew Chlebica, Manager Compliance and Information on (03) 9655 6873. This advice is effective immediately.

Approved by Stephen Turner – Director, Bus Safety. 15 November 2012