Which statement is true?

• A. In 1884, William Dunn and Alfred Bowers stamped the first metal airplane wing.
• B. World War I decreased the need for skilled workers in the sheet-metal trade.
• C. In colonial America, a master was required to provide food, lodging, clothing, and wages to the apprentice.
• D. In 1940, the Lockformer Company developed the Pittsburgh machine.

Answer: (D)

The true statement reflects a historical milestone in sheet metal fabrication: the Lockformer Company developing the Pittsburgh machine around 1940. This machine was designed to form and join Pittsburgh seams in ductwork efficiently, which meant faster production, more consistent joints, and reduced manual labor. It marks a notable shift toward mechanization in duct fabrication, aligning with the broader trend of improving productivity in manufacturing during that era.

For context, the other claims don’t fit historical facts. The first metal airplane wing wasn’t stamped by William Dunn and Alfred Bowers in 1884; metal aircraft structures were developed later, with early all-metal designs appearing in the early 20th century. World War I did not reduce the need for skilled sheet-metal workers; wartime production typically increased demand for skilled labor. In colonial America, apprentices were generally bound to receive instruction and board (food, lodging, clothing) rather than wages as part of their training.