Boeing just can’t seem to catch a break with the beleaguered 737 MAX. The MAX has been grounded for almost a year after two of their newest airliners crashed, in part because of a faulty trim system known as the Maneuvering Characteristics Augmentation System, or MCAS. Now, Boeing has revealed that foreign object debris, or FOD, has been discovered in the fuel tanks of some 737 MAX airliners parked and awaiting delivery, though they won’t say exactly what sort of debris was found. This setback joins a list of problems for the troubled airliner including more software faults that were uncovered during the redesign of the MCAS system, as well as problems with the trim actuator. Despite the latest discovery, Boeing says that the company is still on track to return the MAX to the skies by the middle of the year.