COLUMBIA, SC (WBTV) - A hidden danger could be lurking on thousands of school buses across North Carolina and South Carolina.
WBTV has been investigating problems with heater hoses on Thomas rear engine school buses bursting and spraying hot antifreeze into school buses for two years.
Our questions were triggered by an incident in Union County in May 2015 that left a Porter Ridge Middle School student with burns across much of her lower body.
In that case, a plastic heater hose fitting cracked and sprayed hot antifreeze into the bus.
Our investigation continued after a school bus from Lexington County, South Carolina sprung a leak in February, injuring six students.
The two incidents make up just two of at least nine such heater hose leaks identified by WBTV across the country since 2011.
Even as the incidents continue across the country, the buses' manufacturer, Thomas Built Buses, has failed to address the problem.
WBTV tracked nine incidents across the country
Searching publicly available media reports online, WBTV was able to find at least nine incidents across the country involving a heater hose leak on a Thomas rear engine school bus.
The incidents happened in North Carolina, South Carolina, California and Maryland.
In all but one incident confirmed by WBTV, the Thomas rear engine bus was made in the late 1990s.
The nine incidents all happened since 2011. Dozens of children have been injured by heater hose leaks every year.
In North Carolina, the problem got to be so bad the state Department of Public Instruction sent a memo to transportation directors across the state in 2013 recommending the plastic heater hose fitting be replaced on Thomas rear engine buses.
"The heater hose fittings and connectors that are plastic should be replaced with comparable metal fittings," the advisory memo read. "This action is recommended in an attempt to prevent any further injury to passengers in the event of an engine overheating condition that possibly can cause this issue."
But without a recall requiring the replacement to be made, there was no guarantee the replacement would ever be made.
That became obvious two years later, in May 2015, when another heater hose leaked in Union County.
Parents speak out after daughter burned in Union County incident
Marty and Lisa Shuler vividly remember the frantic moments after they learned their daughter had been injured in a school bus incident less than a mile from her house.
Lisa Shuler said she was called by one of her daughter's friends who said there had been an accident.
She said she hung up the phone and then called back because she thought it may have been a prank.
When she called the second time, she said, she could hear her daughter screaming in pain in the background.
Marty Shuler, who was at home when his wife called and told him about the incident, said he rushed to the scene and found chaos. A paramedic was working on his daughter, who he said was shaking with pain.
In the days following the incident, an On Your Side investigation learned that UCPS transportation officials did not replace the part as recommended.
"I just don't understand, I just kind of shake my head," Lisa Shuler said. "It's such a simple fix. And the fact that they knew about it ahead of time, I don't even know what to say."
State transportation officials at NCDPI issued a second memo regarding plastic heater hose fittings on Thomas rear engine buses in the wake of the 2015 heater hose leak.
This time, county transportation directors were directed to replace the plastic parts for metal parts. Each metal fitting cost about $2.00.
No warning from manufacturer
In South Carolina, state education leaders say they were unaware of the problem with heater hose leaks on Thomas rear engine school buses before a bus belonging to Lexington County 1 school district had a heater hose leak in February.
"When I heard it happen, they were all like 'get out, run, run' and all that," one student told WIS after the incident. "I was really scared. I didn't know what happened. The smoke was coming."
A total of six high school students were injured in that incident.
A spokeswoman for the school district said the plastic heater hose fittings had been replaced with metal fittings but that didn't stop the hose from bursting due to too much pressure.
The bus in Lexington County was locally owned by the school district. But most buses in South Carolina are owned and maintained by the state, which still operates more than 1,200 1995 and 1996 Thomas rear engine buses.
But State Superintendent of Public Instruction Molly Spearman said she was unaware of the potential for heater hose leaks on Thomas rear engine buses prior to the February incident.
"We sent information out to all of our bus inspectors, our mechanics around the state to notify them to be extra careful and take an extra step towards inspecting that part," Spearman said in the wake of February's heater hose leak.
Still, any maintenance to replace the plastic fittings or other work that could prevent another leak will have to be done at expense to taxpayers. Thomas Built Buses would only have to pay for the replacement if it issued a recall, which it hasn't done.
"You would think if there are multiple incidences happening that the company would notify you," Spearman said. "We have a good relationship with the company. We do a lot of business with them. But it is a high responsibility for them to take these kinds of things very seriously."
Other buses recalled
Thomas Built Buses has acknowledged a problem with plastic or rubber heater hose buildings in new model rear engine buses.
The company issued a recall for its 2014-2017 model year Saf-T-Liner HDX school buses in May 2016.
"A rubber elbow may have been used in place of a glass-filled nylon fitting," the recall report said. "The elbow may restrict coolant flow and increase stresses in the elbow. The increased stresses may lead to premature failure of the elbow."
But Thomas refused to answer questions from WBTV about why it didn't issue a similar recall for older buses, even after we sent them a list of heater hose incidents across the country.
A spokesman for the company declined to answer questions on camera or in writing but did issue the following statement: