The stoppage, which also disrupted 767 output including KC-46 tankers, has persisted after a settlement in late September, according to Boeing workers and court filings cited by Reuters.
Boeing's production problems have often been traced to big suppliers and complex parts. The latest one involves a small company in Florida.
A dispute between Boeing and supplier Vaero has halted production of the 777 freighter for nearly two months and disrupted output of the 767, including freighters and the KC-46 aerial refueling tanker, Reuters reported, citing three Boeing workers and court filings.
Boeing filed a complaint against Vaero in August. The two sides reached a settlement in late September, but production of the 777 freighter had yet to resume, the workers said, according to the report.
The report appeared after the market closed on Friday. Boeing shares had ended the regular session at $188.35, up 0.4%.
Why a small supplier can stop a big line
Aircraft are assembled from thousands of parts, and some components come from a single qualified source. When one of those suppliers stops delivering, there may be no quick substitute, because a replacement would need to be certified. A modest dispute can therefore halt a production line worth far more than the supplier's own business.
What is at stake
The 777 freighter and the 767 serve Boeing's cargo customers, and the KC-46 is a military tanker program. Boeing's August complaint said the disruption was costing it as much as $6.5 million a day, according to Reuters. A two-month interruption on two lines would also weigh on deliveries.
Contained or a sign of something wider
One reading is that this is a specific contractual dispute that has already been settled, and that production will resume once supply is restored, with lost output made up over time.
The other is that a settled dispute that still has not restored production points to deeper difficulties at the supplier or in requalifying parts, and highlights how fragile parts of Boeing's supply chain remain.
What to watch
Any Boeing statement on the 777 freighter and 767 lines, delivery figures for October, and management's commentary when the company reports third-quarter results on Oct. 27.