China Tests Local Alternatives for C919 Aircraft

At an aviation forum in Guangzhou, Zhang Xiaoyan named five unglamorous parts of the C919 that China wants to make at home: sealants, rubber, paints, bolts and cleaning agents. Some domestic products are already being tested on the aircraft, while others are being assessed by its state-owned manufacturer, Comac.

The C919 entered commercial service in May 2023, and Comac had delivered 42 C919s to Chinese customers by July. One local product has gone further than testing: HM1176, a polythioether sealant, has been used on the C919 and China's CJ-1000 engine series since 2025. It provides structural sealing and protection against corrosion.

The goal is not to remove every Western supplier overnight. Zhang said US and European companies still make many of the advanced functional and composite materials used throughout the aircraft, and described their products as reliable. Specialized cleaning agents imported from Western suppliers are also reportedly required for some engine-maintenance operations. The localization campaign is meant first to create backup sources against supply disruptions and geopolitical tensions.

The engine remains the hardest gap. The Leap-1C, produced by CFM International, a joint venture between GE Aerospace and France's Safran, is currently the only engine available for the C919. China's CJ-1000 is still under development and is intended to become a domestic alternative. Military-aviation coatings, adhesives and chemical buffering agents could also be adapted for civilian aircraft, including the C919 and the C929 widebody under development.

So what changes in practice? Comac and Chinese maintenance teams could eventually have more than one source for materials that keep an aircraft sealed, protected and serviceable. That could make production and upkeep less exposed to a foreign supplier interruption, but it does not yet mean a fully localized jet: Western components remain embedded throughout the C919, and replacing established products is expected to take years. European Union Aviation Safety Agency certification is still pending; test pilots completed in-flight assessments in Shanghai in July, but regulators must analyse flight data and carry out further technical work.