Incident: Smoldering in belly pan of CAT Skid Steer.
06/15/25 1400-1600
Assistant Fire Engine Operator. (operator of the Skid Steer at time of incident)
I shut off the machine, grabbed the fire extinguisher and radio and proceeded to the engine compartment to inspect. I first turned the fuel shut off and main power supply key. With further inspection I could see at least three separate embers in the belly pan in the engine compartment. As they were only slightly smoldering, I decided to hold off on spraying with fire extinguisher and keep an eye on it while I called the engine crew to come assist with water and tools.
A few minutes later while waiting for the engine to arrive, I noticed a small spot on the rubber sheet that divides the engine compartment from the rest of the belly, had started to glow and increase smoke output. I sprayed 3-4 bursts on the areas of concern with the fire extinguisher to cool down the smoldering.
At approximately 1440, the engine crew with 4 personnel arrived on scene and we worked together to wet down the bottom of the engine compartment, take off rear belly pan accesses panel and lift cab for better access. We cleaned out any smoldering material and thoroughly extinguished with water. After observing for a few minutes to make sure there was no further heat or damage to machine (besides a small hole in the rubber sheet), I decided to bring Skid Steer back to the office for further inspection and cleaning.
Supplemental 06.17.2025
From: Heavy Equipment Operator / Huron Shores Ranger Station
On the above date I reviewed the operators statement on the incident that occurred on 06.15.2025. In the review it was noted that he did all necessary actions to be taken during an incident like this. He is a fully qualified skid steer/masticator operator and has been since 11.15.2022. He has operated the skid steer/masticator 43 times independently as a qualified operator all without incident. This incident was not due to negligence in operations or lack of experience and/or knowledge of the machine. This incident was due from a heat source that came in contact with normal buildup in the engine compartment belly pan during a time period where it has been hot and dry in the area where the equipment was being used.
We inspected the equipment together and went through step by step of his actions that day and the outcome of the incident. We also reviewed all pictures taken before and after. It was noted that there was some minor, but normal, buildup of material in the engine compartment belly pan that ignited and smoldered causing the chloroprene rubber firewall between the engine compartment and cab compartment belly pan to catch fire and smolder. The chloroprene rubber effectively did its job by not igniting fully and keeping material out of the cab belly pan in addition to the operators efforts of extinguishing the smoldering material with a fire extinguisher.
It is of my opinion that the only heat source available to ignite the material was caused by a regeneration process that occurred 1-2 hours before the smell of smoke and visible signs of smoke were noticed. The operator stated that the machine regenerated between 1200 and 1300 hours and that the smell of smoke was noticed at approximately 1410 hours. This would tell anyone that the heat source came from the regeneration process which generates an abundance of heat throughout the entire system and also discharges heat particles from the exhaust which can be sucked into the engine compartment through its fan cooling system.
Mitigation measures are as follows:
1. Fire extinguisher will be replaced with new fire extinguisher.
2. The chloroprene rubber firewall will be repaired before utilizing the machine.
3. A ratchet and socket with the appropriate size will be placed in the machine to remove belly pans on site at any location of a site.
4. Status quo rehab procedures will continue to take place to include blowing off of machine, engine compartment, cab, drum, and all filters along with proper grease intervals.
5. Once a week, during dry conditions, the belly pan access panels will be removed from both the engine compartment and cab belly pan along with a full detachment of the cab to gain full access for thorough cleaning utilizing one of the engines to clean the belly pans out.
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