Why the DC-3 Wing Never Wore Out, Why Was The Douglas DC-3 Such An Important Aircraft?
Video from the channel Flight Origin about Douglas DC-3, linked on its Above Ten Thousand entry. Duration: 13:43. Language: English. Video type: Documentary.
What it's about
A piece explaining why an airframe designed in the 1930s, the Douglas DC-3, is still flying ninety years on. It rules out both the idea that the aircraft beat metal fatigue and that its longevity is down to luck.
Historical context
The project began in 1933, when C. R. Smith, president of American Airlines, asked Donald Douglas for an aircraft to replace his Curtiss Condor biplanes. Chief engineer Arthur Raymond led the Douglas Sleeper Transport, which flew on 17 December 1935 with Carl Cover at the controls; the 21-seat day version became the DC-3. Its multi-spar wing and stressed Alclad aluminium skin were calculated with the generous static margins of the era, when fatigue standards did not yet exist. The cabin was also unpressurised, so the aircraft never endured the load cycles that broke apart the Comets in 1954 and the Aloha Airlines Boeing 737 in 1988.
Key facts
More than 16,000 DC-3s and C-47s were built counting licensed production. The number still flying has fallen from around 2,000 in 2010 to roughly 150 today. Their survival rests on mandatory inspections such as those under FAA circular AC 91-60 (1983), which check spars, skin joints and control anchorages. Basler Turbo Conversions, in Oshkosh, Wisconsin, rebuilds the airframes in around six months and 50,000 work-hours, fitting Pratt & Whitney Canada turboprops. Only about 10% of the original material is retained, and the FAA certifies each BT-67 as a zero-time aircraft.