Investing.com -- Shares in Boeing (NYSE:BA) slumped on Friday after the planemaker said that it and supplier Spirit Aerosystems (NYSE:SPR) had expanded the scope of their inspections into a production defect on its 737 Max 8 jet.
Boeing first said in August that it had found a new quality issue with the 737 Max aircraft that involved Spirit, adding that the problem was related to improperly drilled holes on the aft pressure bulkhead made by an automated drill.
The expanded inspections are now looking into hand-drilled holes, trade publication The Air Current has reported.
Boeing said in a statement that it is taking the "time necessary to ensure each airplane meets our standards and regulatory requirement prior to ticketing and delivery."
Spirit, meanwhile, told Reuters that is continuing to work closely with Boeing on the matter. Shares in the firm also slipped on Friday.
Earlier this week, Boeing said deliveries of its 737 Max planes had fallen in September to the lowest level in over two years, reflecting disruptions to the output of one of the world's biggest jetmakers caused by the fuselage snafu with Spirit. Boeing's production is now running at around half of its target.