Boeing Co, the world's second-largest commercial planemaker, will delay deliveries of 737 model aircraft because of faulty parts and repair existing jets, hampering a recovery from a two-month machinists strike.

"It's a big deal," said Michel Merluzeau, an aviation consultant at G2 Solution in Kirkland, Washington. "They're going to miss their production numbers by a huge margin this year."

A Boeing supplier has been using bad nutplates - inch-long fasteners that attach wiring and other components to the inside of the 737's body - since August 2007, said Vicki Ray, a spokeswoman in Seattle for Chicago-based Boeing. The parts may be installed on 394 of the planes that Boeing built between August 2007 and October 2008, according to its website.