Air Transportation: The Stress Of Substitution


October 23, 2020: Harbin, the Chinese firm that produces, under license, the French three-engine SA-321 helicopter, has introduced a new model based on the SA-321; the Z-8L. This version strives to overcome the shortcomings of earlier Z-8 models, including the Z-8A, which the Chinese Army abandoned after six years because of poor performance at high altitude. This was partly due to the inadequate Chinese WZ6 engines. The new Z8L claims better reliability and several new accessories and capabilities. This not include the ability to operate effectively at high altitudes. The army and navy are both evaluating the Z-8L. The navy will probably find the L model useful and purchase some. The army is more dubious.

While the army will continue to use the few Z-8s it has, it turned to the Z20, another Harbin product that is a copy of the American UH-60. This helicopter uses two of the more powerful WZ10 engines. Nicknamed the “Copyhawk” due to its similarity to the American Blackhawk, the performance of the Z20 has made a difference but the army wants to test it thoroughly to ensure that Harbin has not just created another Z8.

The various Z-8 models are based on the French SA-321, a three-engine 1960s design that ceased production in 1981 after selling about a hundred helicopters. China purchased a dozen naval versions of the SA-321s in the late 1970s, and by 1976 were working on reverse engineering them and producing their own, semi-legal, version. China did receive a license to produce the French Turmo III engine and introduced their version as the WZ6. The first flight of the SA-321 clone (called the Z-8) took place in 1985. Over the next two decades naval, civilian and army models were introduced, with mixed success. Only a few dozen of the original Z-8 were built before it was abandoned by 2018. There were too many technical problems, especially compared to the more reliable and attractively priced Russian helicopters.

Meanwhile another Chinese firm, AVIC Helicopter, produced a civilian version of the SA321, the AC313, which entered service in 2013 and so far about 40 have been ordered or delivered. Better designed and built than the Z8, the AC313 uses Canadian PT6B-67A engines. This makes a big difference in terms of performance and reliability. As a civilian aircraft the manufacturer can import Western engines. The AC313 can be exported and the manufacturer plans to build at least 300 to supply both domestic and export markets.

Military models are produced under different rules, and there are sanctions on China making it difficult to import military grade aircraft engines. China has had a difficult time producing their own engines and that is one reason the Z8 and several other military aircraft have not performed as well as expected, or required. Harbin persisted with their efforts and produced versions of the Z8 the navy was satisfied with. The only SA321 copy that performed to army specifications was the AC313. As a civilian aircraft, the army could not use it if China wants to export the AC313, and other civilian transports as well. AVIC had a solution for that and a military version of the AC313, the Z18, entered service in 2018. AVIC used the Chinese WZ6C engines. The Z18 used a lot of the design ideas that were so successful in the AC313. The army is evaluating the Z18 but has definitely ditched the Z-8 for the Z-20. If successful, the Z18, with a larger capacity than the Z20, would serve mainly as a cargo transport.

The navy was content with the original SA-321 and the Z-8 clones largely because they work fine at sea level. The navy has ordered Z-18s to replace their Z-8s. So far the army seems to like their new Z20. The Chinese army plans to order more Z-20s if CopyHawk succeeds where the Z-8 failed, and that has apparently come to pass.




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