One of the 19 KTX-Sancheon high-speed trains has been pulled off line as the system is now under examination by the manufacturer due to a serious structural fault, sources said Wednesday.

KTX-Sancheon, or KTX-II, is the first high-speed train produced with locally developed technology that went into service early last year.

The train has been in the spotlight in recent months due to frequent breakdowns and accidents including a derailing in February.

According to KORAIL, two of the structures holding motor decelerators in place were found to have developed visible cracks during a routine inspection on May 7.

Motor decelerators regulate the train’s motor block to control movement, and according to industry sources a motor decelerator becoming detached during high-speed movement could cause derail a train.

The vehicle with the fault went into service last March. KORAIL currently operates 19 KTX-Sancheon trains.

According to Hyundai Rotem that produces the trains, all 19 were checked but problems were detected in only one car. While the company confirmed that the faulty vehicle is now being examined, it denied any request for a recall.

“There was no official demand for a recall, but there was a request for a detailed examination and as that is not possible on site, No. 2 train was moved to out factory,” a Hyundai Rotem official said.

He added that each KTX-Sancheon train consists of 10 carriages including the driver’s car, and 19 KTX-Sancheons are in operation and that only the driver’s car of No. 2 KTX-Sancheon is being examined.

“We do not know the cause of the problem. As the train has been running for more than a year, determining the cause of the fault will need close examination.”

The Hyundai Rotem official also said that while each train undergoes a 5,000 kilometer test run before being delivered, not all faults are detected during the test phase and that the company is now working to fix any potential problems that may have been overlooked.

By Choi He-suk  (cheesuk@heraldcorp.com)