CHICAGO (CBS) — New CTA ‘L’ cars that have been shelved since December will not be back on-line until June, as important repairs must be made first.

As WBBM Newsradio’s Bernie Tafoya reports, the Chicago Tribune says the reason the Chicago Transit Authority pulled the new ‘L’ cars off the tracks in December was because of potential safety problems caused by defective steel parts made at the Sifang foundry in Qingdao, China.

LISTEN: WBBM Newsradio’s Bernie Tafoya reports

The CTA had pressed 40 new 5000-series cars into service on the Pink Line, and 52 more had been delivered, when they were all suddenly withdrawn because of multiple flaws in the wheel assemblies.

The CTA has a $1 billion contract for 706 new rail cars with Bombardier Transportation of Canada. The agency is the first to order the new 5000 Series train cars from the company, and the Tribune says the poor craftsmanship on the train car parts is raising major questions about the quality control process at Bombardier.

Still, asked in January if he feared that the new ‘L’ cars could be lemons, CTA President Forrest Claypool said he did not.

Bombardier has had recent quality issues with rail cars being delivered to the Swedish, French and German state railroads. Those deliveries have resumed.

Until enough of the new cars are in service, the 43-year-old 2200-series cars will continue in operation.

Ironically, the 2200s also had a problem as deliveries were made in 1969 and 1970, with the third rail shoe used to collect power. That problem was resolved quickly and replacements were made. The cars have remained in continuous service since then.

The Tribune reports Bombardier is replacing the substandard parts with new ones made in other factories in China and Germany, and that the company will assume any costs the CTA has racked up in dealing with the problem.