Boeing Model E75N1, c/n 75-5392, U.S. Army PT-13D, s/n 42-17229, on the initial test acceptance flight over Wichita, Kansas. Photo from the collection of the EVV Aviation Archives, Evansville, Indiana.

Boeing Model E75N1, c/n 75-5392, U.S. Army PT-13D, s/n 42-17229, on the initial test acceptance flight over Wichita, Kansas. Photo from the collection of the EVV Aviation Archives, Evansville, Indiana.

Several years ago at a mid-western air show, a Boeing E75N1, (often listed as a E75), arrived, all decked out in military colors.The E-75N 1’s Data Block containing the s/n (serial number), which was portrayed under the left cabane strut, stated that this was an U.S. Army PT-13D, s/n 42- 17229. The owner / pilot of this craft was asked what year this airplane was manufactured by an airshow attendee. “1942” was the reply. Another enthusiast asked the pilot “where did you get this information, please”. The pilot’s reply was “the first two numbers in the serial number, is the year of the DOM (date of manufacture”). In the case of this airplane these two numbers were “42”.

When the pilot was further asked if he knew about the FY, (Fiscal Year) he walked away, apparently disgusted or dumbfounded, or maybe both!!! This is often the situation when the DOM comes into discussion, for it is indeed a somewhat mysterious matter.

One usually finds on the CAA, now FAA, records, the date of the U.S. Army’s / U.S. Navy’s acceptance of the Boeing Model 75 listed as the DOM, and almost 99.999% of the time this is not the actual date the Boeing Model 75 rolled off of the Boeing assembly line ready for the Boeing and Military pilot’s initial acceptance flight test.

The first two nos. listed on U.S. Army’s Boeing 75s , (PTs), is the FY, (Fiscal Year) in which the airplane was contracted for. In the case of s/n 42-17229, this was the fiscal year of 1942, which was Tuesday, 01 July 1941 thru Tuesday, 30 June 1942.

In the case of this particular Boeing Model 75, PT-13D, USAAF, (U.S. Army Air Force) s/n 42- 17229, Boeing c/n, (constructors serial number), 75-5392, the initial Wichita Division of the Boeing Airplane Company, Wichita, Kansas’ history of the airplane is; Wednesday, 01 March 1944 – Airplane is accepted by an U.S. Army test pilot at the Wichita Division of the Boeing Airplane Company, Wichita, Kansas.

Monday, 06 March 1944 – The U.S. Army takes delivery of the airplane at the Wichita Division of the Boeing Airplane Company, Wichita, Kansas, and assigns the airplane to a CPS, (Contract Pilot School), the Coast Aviation Corporation, Eagle Field, Dos Palos, California. Boeing c/n 75-5392 is no longer carried on the FAA records.While the U.S. Navy had the U.S. Navy’s BuAerNo (Navy’s s/n), on their N2S Model 75s on the fin of the airplane, there was no reference to the FS marked on the U.S. Navy’s N2S airplanes.

Ken Wilson “Largely a Little Known Aviation Historian”

EDITOR’S NOTE: Ken Wilson is probably one of the best and most knowledgeable Stearman Aviation authorities in this country. – Ken McCullough