Boeing Co. has uncovered an additional manufacturing problem with its 787 Dreamliner, according to a person familiar with the matter, as it works with U.S. regulators to restart deliveries of the beleaguered jet.

The issue pertains to wrinkling in the forward pressure bulkhead in the jets’ noses, the person said, asking not to be identified because the details are private. The defect isn’t considered a threat to flight safety, the person said.

Boeing has halted deliveries of the advanced aircraft since early May while regulators review how it determines where to inspect for tiny imperfections that have cropped up on the interior lining of the jets’ carbon-fiber airframes. With about 100 Dreamliners sitting in storage, restarting deliveries is crucial to the company’s turnaround after it burned through about $20 billion last year.

The Federal Aviation Administration said in a statement that is aware of a manufacturing quality issue near the nose on certain 787 Dreamliners in the company’s inventory of undelivered airplanes.

“This issue was discovered as part of the ongoing system-wide inspection of Boeing’s 787 shimming processes required by the FAA,” according to the statement. “Although the issue poses no immediate threat to flight safety, Boeing has committed to fix these airplanes before resuming deliveries. Based on data, the FAA will determine whether similar modifications should be made on 787s already in commercial service.”

The Chicago-based planemaker will update the market on its June monthly sales totals Tuesday morning. Shares of Boeing were off 1% to $235.90 at 5:48 a.m. in New York, before the start of regular U.S. trading.