A look at the 7000-series railcar before it debuted in 2015. (Photo by Sarah Anne Hughes)

The wiring on Metro’s new 7000-series trains needs to be inspected and parts may need to be re-done, according to a new report from the agency’s Department of Quality Assurance, Internal Compliance & Oversight.

Wires were improperly crimped or twisted together during the manufacturing process. All 548 cars currently in use will need to be taken out of service in phases over the next year. It will not affect daily service, Metro says.

The wiring problems is a long-term reliability issue, Metro spokeswoman Sherri Ly said. She couldn’t comment on which specific systems would be affected if the wiring failed.

Metro’s report said the wiring defects went “undetected” by the 7000-series railcar manufacturer, Kawasaki, and that Metro’s inspectors discovered the problems.

Metro is working with Kawasaki on the inspection and repairs and the work shouldn’t take away time from other maintenance, Ly said.

The report also found workmanship issues in welding and painting.

Kawasaki’s warranty will cover the cost of repairs.

Metro is not accepting new cars from Kawasaki’s Lincoln, Nebraska, plant until the issues are corrected. Nearly 750 cars are supposed to be delivered by summer 2019. Ly said Metro expects deliveries to resume later this month and go back to regular deliveries in September.

The railcars first went into service in 2015.

This story was first published on WAMU. It was updated with new information from Metro and to correct a statement about the maintenance load for the agency.