It said Boeing had not warned it of any delays to its delivery schedule. Related: China's 'Homegrown' Competitor to 737 Takes to the Skies American Airlines Group Inc., which has 100 737 MAX jets on order, declined to comment when contacted by Reuters. The discs in question are made by a supplier to CFM International, a joint venture of General Electric and France's Safran. GE spokeswoman Jamie Jewell declined to identify the supplier. She said GE and Safran will work with the supplier to find and correct any shortcomings in the manufacturing process while also turning to a backup supplier to keep production of engines on schedule. A Boeing logo on one of the firm's 737 Max 9 jets. Jason Redmond / AFP - Getty Images file In a written statement, Boeing said it will work with CFM "to understand the precise scope and root cause of the quality issue." New planes and parts go through extensive testing to turn up problems before passengers go on board.