China Southern Airlines Complains About C919 Delivery Quality: Multiple Faults Recurring, Demands COMAC "Must Not Conceal"Recently, a document purportedly an internal complaint letter from China Southern Airlines has been circulating online.The document shows that after two newly received domestically produced C919 passenger aircraft entered service, multiple faults emerged one after another, including oil leaks in wing dry bays, fractures in fire alarm detection loop brackets, ablation of power panels, detachment of flap panels, and jamming of anti-icing air doors, among other issues.The complaint letter states that some faults had already been identified during the delivery test flight phase, but after the aircraft were delivered and put into operation, the issues continued to recur. China Southern Airlines demands that COMAC fully disclose problems exposed during the aircraft's production and test flight phases, "must not conceal" them, and submit targeted rectification plans to restore customer trust.The document is dated May 27, 2026, and bears the official seal of China Southern Airlines Engineering and Technology Branch.