Some Boeing 787 turbine blades can crack within 1,000 flights: Chinese study

Some turbine blades in GE Aerospace engines on Boeing 787s can develop cracks within about 1,000 flights, leaving airlines to choose between pulling engines early and flying on under strict inspections, according to a paper published in China. The paper, by Xia Xiaofeng of Xiamen Airlines, ran in the September issue of the Chinese aviation industry journal Aviation Maintenance & Engineering, the South China Morning Post reported this month.It examined first-stage high-pressure turbine blades in the Phase 2 and Phase 2+ configurations of GE's GEnx-1B, one of the 787's two engine options alongside Rolls-Royce's Trent 1000, drawing on global fleet data and the maintenance experience of an unnamed Chinese airline.High-pressure turbine blades work under extreme heat and mechanical stress and rely on heat-resistant coatings and internal cooling passages to cope. Although the blades studied carry cooling improvements over earlier designs, their reliability in service has fallen short of expectations, with some deteriorating prematurely, the paper says."Within about 1,000 cycles of installation, the blades often develop radial cracks," Xia wrote. "These cracks typically appear between the first and second, or second and third, rows of cooling holes on their convex surfaces."A flight cycle is one takeoff and landing. The cracks can spread and link up, eventually causing pieces of metal to break away."The airline's Boeing 787 fleet recorded five engine removals caused by defects in Phase 2/2+ HPT blades," Xia wrote. "All involved material loss between cooling holes on the blades' convex surfaces.""According to GE's analysis, the cause of the defect is thermal fatigue," Xia added, describing it as a form of low-cycle fatigue closely linked to stress concentrations created by the shape of the affected area.The paper also documents deteriorating thermal barrier coatings along the blades' trailing edges, which can expose the metal underneath to oxidation and further damage. In high-thrust GEnx variants, cracking and lifting of the blade-root platform have caused three engine removals across the global fleet.Early blade damage does not necessarily make an engine unsafe to fly, the newspaper noted, but airlines must track how it develops and arrange replacements before defects pass permitted limits. Replacing an engine early can bring substantial maintenance costs, require spare equipment and disrupt flight schedules.In the case the paper details, a borescope inspection found material missing between two sets of cooling holes on one Chinese airline's engine, identified only as 956XXX, after its turbine blades had completed 1,818 cycles. A borescope is a tool for inspecting hard-to-reach parts.Under the aircraft maintenance manual, the engine would normally have had to be removed for repair within 10 more cycles. The airline instead ran an engineering assessment and sought GE's approval to keep it flying, and GE initially recommended another borescope inspection within 10 cycles."A follow-up borescope inspection after eight cycles confirmed no significant progression of the defects," Xia wrote. "After the findings were reported to GE, the manufacturer approved another 30 cycles of operation."The airline flew the engine only four more cycles, 12 in all since the defect was found, and removed it for maintenance once it had secured a spare engine and arranged the swap. A Japan Airlines Boeing 787 Dreamliner rolls along a runway. Illustration photo by Unsplash/Ryuta As of August 2025, about 417 GEnx engines worldwide, 15% of the global fleet, were still running with Phase 2 or Phase 2+ turbine blades, according to GE data cited in the paper. The longest recorded time on wing for the configuration was 4,729 cycles, compared with 3,683 cycles for engines operating in severe environmental conditions, though the paper did not set a fixed replacement life for the blades.GE has repeatedly revised its maintenance criteria as more operational data came in, the paper says. Some small areas of material loss that might once have prompted an engine removal can now be monitored through repeat inspections every 100 or 250 cycles, depending on the type and severity of the damage, which has helped raise the average number of cycles affected engines log before removal.Some engines have since received newer blade configurations, though the paper recommends continued monitoring of their long-term reliability. Xia also recommended more frequent inspections where appropriate for blades past 2,000 cycles, along with closer tracking of engine vibration, exhaust gas temperature and other operating parameters.In 2018, GE began delivering a GEnx-1B durability package that modified the first-stage turbine nozzles and blades, aimed at 787s flying in harsh environments such as the Middle East, Aviation International News reported at the time.On July 19, GE Aerospace said upgrades to the engine's high-pressure turbine blades and combustor coatings over the past decade had more than doubled its time on wing in harsh environments.