United Airlines Holdings Inc. discovered dubious parts in two aircraft engines, adding to the list of carriers worldwide that have found bogus components from supplier AOG Technics Ltd.

The parts were discovered in a single engine on each of two aircraft, including one that was already undergoing routine maintenance, a spokesperson for United said Monday. The Chicago-based airline is replacing the engines before the planes are returned to service, he said.

United will continue to investigate the bogus parts as more information becomes available from its suppliers, the company said.

The company’s disclosure makes it the latest major carrier to confirm that suspect components from AOG were installed in their fleet, including Southwest Airlines Co. and Virgin Australia Airlines Pty. Aviation regulators have said AOG supplied an unknown number of jet engine spare parts backed by falsified airworthiness documentation, kicking off a worldwide effort by the industry to hunt down more components.

Airlines, Engine Makers Race to Track Down Bogus Spare Parts

CFM International Inc., the joint venture of General Electric Co. and Safran SA that makes the engines for many older-generation Airbus SE A320 and Boeing 737 aircraft, previously said parts with fraudulent documentation had been used in 68 of its power plants.

--With assistance from Ryan Beene.