WASHINGTON, Oct 14 (Reuters) - Boeing Co (BA.N) and U.S. regulators said Thursday that some titanium 787 Dreamliner parts were improperly manufactured over the past three years, the latest in a series of problems to plague the wide-body aircraft.

The quality issue does not affect the immediate safety of flights, the company and the Federal Aviation Administration (FAA) said.

Boeing said the parts were provided Leonardo SpA (LDOF.MI), which bought the items from Italy-based Manufacturing Processes Specification (MPS). MPS is no longer a supplier to Leonardo, Boeing said. Shares in Italy's Leonardo extended losses and were recently down 5.5%. Boeing shares were down 1.3%.

Leonardo declined to comment. MPS did not immediately respond to a request for comment.

The parts include fittings that help secure the floor beam in one fuselage section, as well as other fittings, spacers, brackets, and clips within other assemblies.

Undelivered aircraft will be reworked as needed, Boeing said, adding that any fleet actions would be determined through its normal review process and confirmed with the FAA.

The defect was found as the planemaker grapples with other problems in its 787 that have caused it to cut production and halt deliveries since May.

Problems started in September 2020 when the FAA said it was investigating manufacturing flaws. Airlines using that model removed eight jets from service.

Boeing was able to resume deliveries of the 787s in March after a five-month hiatus - only to halt them again in May after the FAA raised concerns about its proposed inspection method.

In July, the FAA said some Dreamliners had a manufacturing quality issue near the nose of the plane that must be fixed before Boeing can deliver to customers.

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