Boeing Co. has found that titanium components used by one of its largest 787 Dreamliner suppliers, Italy’s Leonardo SpA, didn’t meet specifications and will need to be replaced on some aircraft made in the last three years, according to a person briefed on the matter.

The flawed parts include titanium spacers, brackets and clips that are used in sections of the carbon-composite airframe that are assembled by Leonardo, according to the person, who asked not to be identified as the matter is confidential. Boeing has asked another key supplier, Spirit AeroSystems Holdings Inc., to do an audit of parts it uses from the same subcontractor: MPS, the person said.

The latest 787 problem clipped shares of Boeing and the suppliers Thursday. But it doesn’t present “an immediate safety of flight concern for the active, in-service fleet,” Boeing said by email Thursday. The company is inspecting jetliners that haven’t been delivered for the defective parts and is repairing two Dreamliners that were sent to customers but haven’t begun commercial flights, the person said.

The defective fasteners add another complication to Boeing’s effort to resolve quality concerns surrounding its marquee wide-body aircraft. The Chicago-based company has more than 100 Dreamliners parked around its factories and in desert storage lots as it works to gain approval from U.S. regulators for a plan to inspect the aircraft for a separate structural defect.

Leonardo said it has dropped MPS, which is also known as Manufacturing Processes Specification Srl, adding that the subcontractor “is under scrutiny by prosecutors.” The Rome-based manufacturer called itself “an injured party,” and said it won’t bear costs associated with the titanium-fastener issue. Leonardo makes the Dreamliner’s horizontal stabilizer and two sections of its fuselage barrel. 

MPS is also a supplier to other aerospace manufacturers, including European planemaker Airbus SE. The Brindisi, Italy-based company appears on an October list of Airbus suppliers.

The U.S. Federal Aviation Administration said it is in touch with Boeing over the flawed titanium parts issue and said it doesn’t affect immediate flight safety.

The planemaker has been conducting a deep dive into production and quality issues with the Dreamliner and other aircraft in the wake of two fatal crashes of its 737 Max. The company halted Dreamliner deliveries earlier this year after finding tiny gaps the width of a hair where the fuselage sections of the plane are joined together.

Boeing fell 2 per cent to US$217.44 at the close in New York, while shares of Spirit fell 5.1 per cent to US$44.17. Leonardo closed 7.1 per cent lower at 6.67 euros in Milan, logging its sharpest decline since November.

The Wall Street Journal reported earlier that Boeing had discovered defective titanium parts on the Dreamliner.