The Boeing Model 40 was a mail plane. It was made in the 1920s. The Boeing Model 40 was a biplane with one engine. It was used a lot to deliver mail in the 1920s and 1930s. It was the first plane made by Boeing which carried passengers.

Development and design
In 1925, the US Post Office asked for a mail plane to replace the DH-4s that it was using then. The new plane would need to use the same engine as the DH-4. A lot of these could be bought. The Boeing Model 40 could carry up to  of mail. The mail was stored in two places at the front of the plane. The wings were made of wood. The Model 40 had landing gear that did not move.

The Model 40 flew for the first time on July 7, 1925. The US Post Office bought the prototype of the Model 40, but it decided to use the Douglas M-2 instead.

Later, Boeing made the Model 40A. The Model 40A had a new engine, which was  lighter than the old one. A cabin was also made, which could carry passengers. of mail. The US Post Office let Boeing carry mail from San Francisco to Chicago in January 1927. Boeing built 24 Model 40As to do this.

The next type of Model 40 was the Model 40C. It had a bigger cabin so that four passengers could be carried. Model 40As had their engines changed to even lighter ones. Model 40As with this new engine were called the Model 40B-2. The Model 40B-4 was another model which had the cabin of the Model 40C and the engine of the Model 40B-2. Boeing Model 40s were made until February 1932.

History
Boeing made its own airline, which was called Boeing Air Transport. It started flying from San Francisco to Chicago on July 1, 1927.

Types of Boeing Model 40

Model 40 Very first design.
Model 40A Another design made in 1927. It had new engines and a cabin which could carry two people. 25 of these were made.
Model 40B These were Model 40As with a new engine. Their name was changed to Model 40B-2.
Model 40B-4 Model 40-Bs with a bigger cabin which could carry four people.  It had windows which could be opened. 38 of these were made.
Model 40B-4A One Model 40B used by Pratt & Whitney for testing.
Model 40H-4 Four Model 40B-4s which were made by Boeing Canada. 
Model 40C Similar to the Model 40B-4, but it had the same engine as the Model 40A. 10 of these were made.

Users
 
 Honduran Air Force
 
 Boeing Air Transport

Survivors

As of February 17, 2008, a Model 40 called Boeing 40C S/N 1043 is the only Model 40 which can still fly. It is the oldest Boeing plane which can still fly. In 1928, the aircraft was damaged after a crash. It was rebuilt by Pemberton and Sons Aviation in Spokane, Washington. On May 8, 2010, this plane flew with Boeing's newest plane, the Boeing 787 Dreamliner.

Many museums have some Model 40s in them.

Details (Model 40A)

Accidents
 February 26, 1928: A Model 40A crashed near Marquette, Nebraska. The passenger died, but the pilot did not.
 November 18, 1930: A Model 40 crashed into a mountain in a storm. All three people on the plane died. 
 January 22, 1931: A Model 40 crashed into a mountain in fog. The pilot died.
 May 5, 1931: A Model 40, crashed into a canyon while trying to land. Both people on the plane died.
 September 16, 1931: A Model 40 crashed into San Francisco Bay after it took off. It is not known why this happened. Everyone on board died.
 November 23, 1931: A Model 40 crashed near Salt Lake Airport. The pilot died.
 November 26, 1931: A Model 40 crashed near Pasco, Washington. The pilot died.
 February 2, 1932: A Model 40 crashed after landing in California. One of the two people on board died.
 May 16, 1932: A Model 40 crashed in fog. All three people on the plane died.

References

More reading

Other websites 

Boeing History – Boeing Model 40A Commercial Transport Retrieved June 17, 2006.
Pemberton and Sons Aviation Website 

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