Boeing grounded its Max series aircraft last year after deadly crashes were linked to faulty software. The company, however, remains optimistic that its fleet will receive the green light to go wheels up by summer.
Aircraft manufacturer Boeing said Tuesday that it found debris contaminating the fuel tanks of "several" 737 Max passenger planes. The 737 Max series was grounded worldwide last year after two fatal crashes.
Boeing's general manager, Mark Jenks, called the debris "absolutely unacceptable" in a memo to employees who worked on the series. "One escape is too many," he added.
Boeing did not specify how many jets were affected and said it made corrections immediately to its system to prevent a repeat of the problem. It built about 400 undelivered Max aircraft before production was halted due to the worldwide grounding of its fleet; the planes with foreign objects found in the fuel tanks were in storage due to this.
Metal shavings, tools and other objects left in planes during assembly can raise the risk of electrical short-circuiting and fires.
Boeing remains optimistic
Boeing is hoping that the Federal Aviation Administration (FAA)will certify the plane to fly again this summer.
FAA spokesperson Lynn Lunsford said the agency has "increased its surveillance based on initial inspection reports and will take further action based on the findings."
Boeing's woes have been mounting since aviation authorities around the world grounded its Max 737 fleet after it was involved in two deadly passenger plane crashes that killed 346 people. The crashes were blamed on an automatic control system malfunction during takeoff.
In February, Fitch Ratings downgraded Boeing's debt rating due to uncertainty about the aircraft's future and reputation damage.