DPI MESSAGE #879 - Bus Fire Prevention

There have been two recent fires on FS65 buses with CAT 3126 engines this school year. The source of those fires is still under investigation, but they appear to have started in the engine compartment. If we receive additional information from the fire investigator we will bring that to your attention.

Please review the information below regarding previous fires on these buses.

This event provides a good opportunity to remind our maintenance staff of several key inspection items that must be taken seriously to eliminate potential causes of fire for these types of buses.

1. In May 2011 - DPI Message # 539 - DPI informed all counties of the potential for fire in the engine compartment due to deteriorating wiring harness wire ties on Freightliner FS chassis. The high exhaust manifold temperatures allowed the alternator wire to fall on the manifold igniting the fire. DPI inspectors have still seen in some bus garages where they have not performed the repair to the valve cover wires as requested or needed additional repairs. Please ensure that these issues are addressed. (see picture below)

2. The expectation when performing a 30-Day Inspection is to inspect the wiring in the engine compartment for damage, chafing or exposed wires. (Page 46 of the NC BUS FLEET: North Carolina School.  Transportation Fleet Manual, North Carolina State Board of Education Policy TRAN-005).  When performing 30 day inspections technicians should also pay close attention to the battery wire showing signs of rubbing/chaffing from a bolt that goes through the fire wall on the FS65 chassis Freightliners. (see picture below, driver side wiring harness between engine and firewall.)

3.The NC Bus Fleet inspection manual stresses the importance of making repairs when oil or fluid leaks are discovered due to this being potential fuel to a fire in the event one occurs.

This message shall serve as a notice that every model year 1998-2003 bus with a Caterpillar engine must be inspected again, and if needed, repaired.

In addition, please ensure that the persons performing the 30-Day inspections are properly inspecting the bus wiring in this specific location and on all buses, in general.

Transportation Directors - Please send a reply email to me so I know that you received this message

Thank you.

Jeff Moore
Transportation Consultant
NCDPI
919-807-3571
jeff.moore@dpi.nc.gov

1999 FS Chassis Freightliner Wiring Harness Fire Hazard

The long red arrow identifies black plastic wire tie that has deteriorating over time due to head from the turbo manifold identified by the yellow arrow.  When the wire ties breaks from the heat it allows a single positive wire from this wire loom to fall on the manifold which shorts out and causes a fire in the engine compartment.  The immediate attention to this is requested to prevent further damage.

FS 65 Battery Wire Rubbing Bolt Through Fire Wall