06/03/2008. Boeing designed the Model 40 mail plane to a specification issued by the Post Office Department, and powered by a 400 hp Liberty 12 twelve-cylinder water-cooled V-engine, the aircraft made its first flight on July 7, 1925. It was bought by the Post Office Department, although no production order was placed.
The Model 40-C was a transport version seating four passengers, powered by a 420 hp Pratt & Whitney R-1340 Wasp nine-cylinder air-cooled radial engine it was first flown on August 16, 1928. Sixteen months later 10 had been delivered:
Produced in 1928, the pictured aircraft is the oldest flying Boeing aircraft in the world and was initially delivered to Pacific Air Transport registered as NC5339. It was substantially damaged in a crash and was grounded for eighty years. It was registered to Addison J. Pemberton as N5339 on June 9, 2000, and after eight years of restoration the aircraft made a twenty minute second maiden flight at Spokane, Washington, on February 17, 2008. The planned re-registration of the aircraft to its original registration N5339 was authorized on April 30, but not actuated as of this day.