Cadet Air Corps Museum AT-10 Restoration Report – Winter 2024

Beech AT-10 Wichita restoration continues to make great progress at AirCorps Aviation!

This WWII-era image captured at Freeman Army Air Field in Indiana shows at least five maintenance crewmen working on an AT-10. The dismountable nose assembly is visible to the lower right. (image via AirCorps Aviation)
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Periodically, we have presented reports from Chuck Cravens detailing the restoration of an ultra-rare Beechcraft AT-10 Wichita WWII advanced, multi-engine trainer. As mentioned in previous articles, the project belongs to the Cadet Air Corps Museum and comprises the remains of several airframes, but is primarily focused upon Wichita 41-27322. The restoration is taking place at world-renowned AirCorps Aviation in Bemidji, Minnesota, and here is their latest update on progress with the Wichita as it stands presently:


Fuselage

As the cover photo reveals, the AT-10’s nose assembly is removable, helping facilitate maintenance operations. Aaron recently fabricated and installed this Nose Assembly, Demountable, as Beechcraft described it.

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The fuselage nose where the “demountable” assembly will be installed. (image via AirCorps Aviation)
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The horizontal stabilizer mounting area almost looks like a piece of furniture. (image via AirCorps Aviation)
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Wooden spacers hold the vertical stabilizer in position as the assemblies are checked for proper fit and clearance. (image via AirCorps Aviation)
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The rudder was found at a technical school and is in good condition – for an 80-year-old assembly – however, it will require restoration work to some of its ribs and the leading edge. (image via AirCorps Aviation)
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View from the rear fuselage. (image via AirCorps Aviation)
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The forward aluminum section is ready for the “demountable” nose assembly to be attached. (image via AirCorps Aviation)
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Aaron has begun assembling the “demountable” nose frame and skin sections. (image via AirCorps Aviation)
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Here we can see the upper left and lower center skin sections are clecoed in place. (image via AirCorps Aviation)
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All skin sections for the “demountable” nose assembly have been fitted and clecoed in place. (image via AirCorps Aviation)
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The lower skins are now riveted in place permanently. (image via AirCorps Aviation)
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Aaron often has to work in tight quarters, and the nose of the AT-10 is no exception. (image via AirCorps Aviation)
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The “demountable” nose assembly is nearly complete. (image via AirCorps Aviation)
 

Steam Forming a Spar for the Horizontal 

A mostly-wooden aircraft like the AT-10 presents a continuing challenge, with its requirements for forming and shaping wood to the required contours. These tasks can be tackled via several technicques, but the use of steam is key to most of them. The infusion of steam softens the lignins in the material, the polymers which hold its cellulose fibers together. When the wood cools, the lignins harden again, holding the material in its newly-bent condition. The horizontal stabilizer’s forward spar is one such component which requires steam-bending. 

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Superior quality aircraft spruce will be used to make the AT-10’s horizontal stabilizer spars. Clear and straight grain is necessary in this application. Wood like this is both rare and expensive! (image via AirCorps Aviation)
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Aaron had to make a steam apparatus to form a curve in the forward spar. This plastic pipe was the starting point. (image via AirCorps Aviation)
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The steam “box” setup is ready. (image via AirCorps Aviation)
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Steam is applied to the center of the spar, making the wood pliable. (image via AirCorps Aviation)
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Forming wood with steam requires two separate procedures, steaming to soften the lignins, followed by clamping the wood to a form. This process assures that the wood will hold its shape until it cools and hardens. (image via AirCorps Aviation)
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The spar has lightning holes. Aaron made a template for accurate drilling and cutting to form the holes
with precision. (image via AirCorps Aviation)
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Here we can see the spar following the addition of its lightening holes. (image via AirCorps Aviation)
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Both front and rear horizontal stabilizer spars are in place on the fuselage as their fit is checked. (image via AirCorps Aviation)
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Another method of creating a curved wooden part is by using a combination of lamination and ammonia. For this horizontal stabilizer leading edge tip, strips of wood were soaked in ammonia, which, much like steaming, breaks down hydrogen bonds within the wood and the lignin cell walls. The procedure allows molecular movement when subjected to tensile or compressive forces. Once the ammonia evaporates from the wood, new bonds are created, leaving a permanent set. (image via AirCorps Aviation)
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This closer view illustrates the different types of wood used in the horizontal stabilizer structure. (image via AirCorps Aviation)
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With the completion of the parts fabrication for the horizontal stabilizer, Aaron could begin the actual assembly of this component. (image via AirCorps Aviation)
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The process of building the stabilizer will remind some ( myself included) of their model-building days. (image via AirCorps Aviation)
 

Wings and Center Section

The outer wings and center section are the next major AT-10 assemblies to undergo restoration. The work began with parts inspection, to determine which of the surviving parts we have are potentially airworthy, and which will require refabricating. 

Aircraft-grade wooden materials are difficult to locate these days, with stock seemingly always on backorder. However, with their recent acquisition of Dusters and Sprayers Supply Inc. (the world’s largest inventory of Stearman parts) AirCorps Depot obtained an extensive selection of aircraft spar stock and plywood – with some 302 items now on inventory. This will be of great benefit to the AT-10’s progress, and especially its center section needs, in terms of cost, shipping, minimum order requirements, and management.

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This is an original wing center section attach plate. It is clearly not airworthy due to the intergranular corrosion. but it will serve as a useful pattern to fabricate a new part. (image via AirCorps Aviation)
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These are also original wing attachment plates. They are for the front spar, and would have formed the junction between the center section and outer wing panels. (image via AirCorps Aviation)
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A closer view of the original attachment plates. (image via AirCorps Aviation)

Want to get involved?

AirCorps Aviation is constantly looking for new technical material related to the AT-10. Due to the rarity of this aircraft, and the relatively low number produced, acquiring engineering drawings, parts catalogs, maintenance manuals, and other ddocumentation has been much more difficult than with our past restorations. If you have any AT-10 material or know someone who does, the team would love to hear from you!

Be a part of helping the AT-10 return to the skies! Contact Ester Aube, by email or phone [email protected] or 218-444-4478. Furthermore, should anyone wish to contribute to the Cadet Air Corps Museum’s efforts, please contact board members: Brooks Hurst: phone: +1-816-244-6927, e-mail: [email protected] Todd Graves: e-mail: [email protected]

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Richard Mallory Allnutt's aviation passion ignited at the 1974 Farnborough Airshow. Raised in 1970s Britain, he was immersed in WWII aviation lore. Moving to Washington DC, he frequented the Smithsonian’s National Air & Space Museum, meeting aviation legends.

After grad school, Richard worked for Lockheed-Martin but stayed devoted to aviation, volunteering at museums and honing his photography skills. In 2013, he became the founding editor of Warbirds News, now Vintage Aviation News. With around 800 articles written, he focuses on supporting grassroots aviation groups.

Richard values the connections made in the aviation community and is proud to help grow Vintage Aviation News.

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About Richard Mallory Allnutt (Chief Editor) 1060 Articles
Richard Mallory Allnutt's aviation passion ignited at the 1974 Farnborough Airshow. Raised in 1970s Britain, he was immersed in WWII aviation lore. Moving to Washington DC, he frequented the Smithsonian’s National Air & Space Museum, meeting aviation legends. After grad school, Richard worked for Lockheed-Martin but stayed devoted to aviation, volunteering at museums and honing his photography skills. In 2013, he became the founding editor of Warbirds News, now Vintage Aviation News. With around 800 articles written, he focuses on supporting grassroots aviation groups. Richard values the connections made in the aviation community and is proud to help grow Vintage Aviation News.

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