Boeing Type 40B-4 Mailplane
United States — Single-engine mail and passenger-carrying biplane

Archive Photos 1

1927 Boeing 40B-4 (NC285) at the Henry Ford Museum, Dearborn, MI

Overview 2

The Boeing Model 40 was a United States mail plane that became the first aircraft built by the Boeing company to carry passengers. It was of conventional biplane configuration with a combination of standard and warren-truss style interplane struts. Originally designed to compete for a US Mail contract in 1925, it was rejected in favor of the Douglas M-2.

The design was revived in 1927 as part of Boeing’s tender for newly privatized airmail routes. Designated the Model 40A, this variant was powered by an air-cooled Pratt & Whitney Wasp radial engine, which offered a 200 lb weight saving over the water-cooled Liberty specified by the postal service in 1925. Although the primary purpose of the aircraft was to carry mail, two passengers could be accommodated in the small cabin, allowing Boeing to operate it on any of the routes that the firm might bid for. The original fuselage design was changed to one using welded steel tubing. Boeing successfully bid on the San Francisco-Chicago route, and Boeing Air Transport commenced operations on 1 July 1927 with 24 Model 40As.

Survivors 2

Variants 2

Operators 2

Boeing Model 40B-4 Specifications 2




Tail Unit


Power Plant



Weights and Loadings



  1. Shupek, John. Photos via The Skytamer Archive, copyright © 2009 Skytamer Images. All Rights Reserved
  2. Wikipedia, the free encyclopedia. Boeing Model 40, 4 December 2009
  3. Grey, C. G. and Leonard Bridgman. The Boeing Type 40-B-4 Mailplane. Jane’s all the World’s Aircraft 1931. London: Sampson Low, Marston & company, Ltd., 1931, p. 253c-254c. Print.


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