From The Dragon's Wings
"CNAC went to great lengths and displayed incredible ingenuity to keep its dwindling supply of aircraft in service. For example, in May 1941 Japanese fighters intercepted Hugh Woods in one of CNAC's new DC-3s while en route from Chungking to Chengtu. He made a forced landing at Suifu as the Japanese dived to attack. Although crew and passengers escaped without injury, Japanese bombs blew the right wing off Wood's DC-3. The 24,000-pound airplane had to be moved from the airfield as soon as possible in order to escape damage from a second strike. CNAC did not have a spare wing section in stock for a DC-3; however, a slightly smaller DC-2 wing was available in Hong Kong. No one really knew if a DC-3 would fly with a DC-2 wing, but it seemed worth a try."
And so, the story of the DC-2 1/2 was born.