E&MU: TMC Fleets Seek Sources of Truck Fires

By Frederick Kiel, Staff Reporter

This story appears in the July/August 2009 issue of Equipment & Maintenance Update, a supplement to the July 6 print edition of Transport Topics. Click here to subscribe today.

Fleet reports of highway tractors bursting into flames, on the road or while parked, raise questions of whether a trend is showing itself and leave only hints as to common causes.

“We have only anecdotal reports from members that the problem is increasing,” said Robert Braswell, technical director of American Trucking Associations’ Technology & Maintenance Council.

TMC sent a questionnaire about “thermal incidents” occurring during the 12 months ending October 2008 to approximately 1,100 fleet managers who were responsible for 64,000 sleeper cabs, 68,000 other types of tractors and 76,000 straight trucks.

The survey generated answers from “about one in 10” of the managers, Braswell said.

The respondents reported 135 fires struck while their trucks were in service and 87 while their trucks were parked.

Carl Tapp, vice president of maintenance at P.A.M. Transport, Tontitown, Ark., and a fleet member of a TMC task force organized to examine tractor fires, said, “We’re seeing more [thermal incidents] in all Class 8 heavy-duty applications.”

Tapp said causes cited in the survey included water intrusion, turbocharger- and idling-related failures and “some electrical fires due to wire routing and clipping issues.”

Clipping refers to how a wire is attached to the truck body or holder to keep it from vibrating.

Some fleets have had no burning incidents at all; for others, it’s a serious matter.

A large over-the-road freight operation that considers cab fires to be one of its “top priorities” is Schneider National, Green Bay, Wis., with 10,000 company tractors.

Schneider had “seven or eight fires last year, and maybe four or five so far this year,” said Steve Duley, vice president of purchasing for the $3.7 billion truckload and logistics company.

Schneider lost a tractor that had been sitting in a yard for as long as two weeks. In another incident, fire broke out as the truck was going down the road, Duley said, “and the driver had to stop it fast and jump out.” The driver was not injured.

Duley said the fires, once they start, spread rapidly. He spoke of trucks combusting in the shop, “and in just a minute or two, they’re completely engulfed in flames.”

No single source and no typical conflagration leaped out at those who are studying truck fires.

Richard Preston, director of maintenance at ABF Freight Systems, Fort Smith, Ark., said electrical factors are suspected, “but we haven’t proved anything.”

Preston also said that at first everyone thought the source might be the higher heat of newer engines, “but that doesn’t seem to be it.”

Starting with 2003 models, engineers have beefed up turbochargers, cooling and other under-the-hood systems to handle a greater rate of heat expulsion by exhaust gas recirculation. Today’s new trucks also come with a particulate filter that needs high temperatures to recharge itself. The filter is generally located outside the engine compartment.

ABF, a less-than-truckload operation, runs mostly day cab tractors and hasn’t had cab-fire problems, Preston said.

When fire seems to spontaneously occur, the extent of destruction hampers those who are searching for telltale signs.

“You’ve got all the plastics and resins with composites in modern trucks, which are good and strong but also somewhat flammable,” Preston said. “Once a fire starts, [the truck] usually burns to the ground, and then it’s difficult to find out what happened. It’s all gone.”

Bill Briscoe, owner of Briscoe Engineering, Roswell Ga., which is a company that attempts to determine the reasons for vehicular accidents, said his firm has been asked by clients to find the causes of trucks that are parked with the engine turned off suddenly bursting into flame. He declined to discuss specific cases.

“What we usually do in an investigation is to discover the circumstances of the event, study the maintenance and repair records, do an examination of the burnt vehicle,” Briscoe said in an interview, “as well as try to talk to the driver.”

Briscoe said this approach would not be effective if the truck were completely destroyed.

TMC’s task force is charged with working with truck manufacturers in collecting data on the extent of thermal incidents and sources of ignition. It is led by Charles Groeller, group manager of Mack Trucks Inc.

Task force members who are fleet managers and who spoke with Equipment & Maintenance Update did not say that specific Class 8 models or nameplates were more susceptible to fires than others.

All North American manufacturers were asked to comment for this article; none responded. Contacted were Freightliner and Western Star trucks, divisions of Daimler Trucks North America; Kenworth Truck Co. and its Paccar stablemate, Peterbilt Motors Co.; Volvo AG’s two companies, Volvo Trucks North America and Mack Trucks; and Navistar Inc. which builds International Trucks.

YRC Worldwide, the largest LTL company, with 26,000 tractors, works directly with the manufacturers on issues like this, said Daniel Miller, manager of equipment processes for YRC Enterprises Services.

A maintenance director for another major fleet, speaking on the condition that he not be identified, pointed to the range of apparent fire causes.

“We’ve have maybe three or four truck fires recently, when we didn’t have any for years, and it was alarming,” he said. “We had a couple that appeared to be started from the turbo, and a few from the power distribution center and at least one of the electrical ones when the engine was off.”

He said that the truck manufacturer offered a satisfactory settlement.

Bruce Purkey, owner of Purkey’s Electrical Consulting, Nashville, Tenn., is vice chairman of the TMC task force. He said, “Most fleets I’ve worked with have fires, and continue to have fires,” but he doubted that heat from the engine and exhaust systems would be a main cause of fires in later-model trucks.

“From the standpoint of design, the truck manufacturers do a wonderful job,” Purkey said. “They use the best possible products, so that when the temperature rises, the materials can support the increased heat. Higher heat has an impact, but due to the advanced materials and the care that the manufactures use, that would negate heat as a factor in most circumstances.”

Schneider’s Duley believes part of the general problem may be traced to the complex circuitry of modern engine systems and the placement of wiring where it is difficult to spot or fix potential problems.

He said fires that ignite when the engine is running could come from water seeping into electrical connections, causing short circuits. Also, more powerful turbochargers can ignite a fire “with any kind of fuel leak.”

The trucks of Air Products & Chemicals transport flammables made in the company’s plants. Managers of the private fleet put road equipment through an intense screening, and sometimes order changes, before placing it in service.

“When we take delivery of new vehicles now, we’re very astute with the wire routing, and the high voltage system of starting,” said Ron Szapacs, the Allentown, Pa., fleet’s maintenance specialist. “We inspect the system to reduce any possible shorts or spark because of what we haul: hydrogen and liquid oxygen. Hydrogen is very flammable and can cause a big fire.”

TMC’s survey responses suggested that a truck’s accumulated service miles are not an indicator of whether the vehicle might be prone to catching fire.

Braswell said the TMC survey attempted to explore fire causes — not the frequency of truck fires — with an eye to drawing up recommended practices to avoid them. 

The task force is drafting some ideas, based on suggestions from the Truck Manufacturers Association, among others.

One possibility is to call for designing starting motors so that if the switch were to stick in the on position, the starter would stop cranking before overheating.

Another example addresses battery inspection during preventive-maintenance, to make sure cables of the opposite polarity never come in contact with each other or rub on any surface that could abrade their protective coverings.

Purkey, a member of the task force, said fleets may unwittingly create their own fire risks when they replace the truck maker’s high-grade wiring and fuses with cheaper, lower-quality products in an effort to save money.

“There are so many possible reasons for these fires that it’s going to take us a long time” to understand them, Purkey said.