TRANS World Airlines (TWA) is to become the first United States airline to lease McDonnell Douglas commercial aircraft made in China. It has signed a tentative agreement to lease five new narrow-body MD-83 jetliners assembled by McDonnell Douglas' Shanghai Aviation Industrial Corp joint venture. The jets are assembled in Shanghai from kits supplied by the US manufacturer, under a 1985 agreement. It is understood planes are being produced 10 to 20 per cent cheaper in China than their US-built counterparts. The offshore production of US aerospace parts and jets has been hotly contested by US trade unions. However, the bulk of the planes being assembled in China are for the local market. Only five of the 35 jets included under the initial 1985 agreement with McDonnell Douglas are scheduled for export.