Overview:
Pioneer Aero began working on the SBD's lower aft fuselage last spring, with Nigel and William Lowen building a jig to restore this significant subassembly, as reported in Update #76. They have made steady progress over the past eight months, stripping it down into component parts, bead-blasting everything, then inspecting for potential airworthiness. Happily, most of the fuselage frames and a fair number of ancillary items were repairable to flight-worthy condition. In our last report on this section of the airframe, Update #89, the Lowens had started placing the restored fuselage frames back in the jig for trial-fitting purposes. They have since begun working on the internal structure as well, which includes the battery tray and radio/radar equipment mounts. This report covers the work performed on these items, along with the lower half of Fuselage Frame #9 too, which required a new diaphragm.
Fuselage Frame #9:
The lower half of Fuselage Frame #9 forms the lead bulkhead in the SBD’s lower aft fuselage subassembly. The frame was disassembled for inspection and repair last spring, as reported in Update #77. After bead-blasting, the parts all proved to be repairable except for the diaphragm which forms the rearmost wall of the gunner’s cockpit. Pioneer repaired the frame's components, then riveted them together last fall. More recently, they refabricated the diaphragm and trial-fitted it to the frame. This diaphragm both added strength to the fuselage, but also prevented any spent shell casings or links from traveling further down the fuselage where they might accidentally snag control lines when the machine guns fired.
The lower half of Fuselage Frame #9 (forward face) soon after removal from the SBD's lower aft fuselage. The frame itself consists of two halves, connected via a plate riveted between them at the center of the bottom edge. While the frame itself proved restorable, the diaphragm needed refabricating. (image via Pioneer Aero)
Here we see the two sections which form the lower half of Fuselage Frame #9 sitting atop one another amongst other parts from the SBD's lower rear fuselage. This image was captured soon after bead-blasting last summer. Note how the damaged outer section of the flange has been removed. A replacement section was fabricated and about to be installed along the row of holes drilled into the outer edge the frame face. (image via Pioneer Aero)
A view from last fall showing the trial-fitting of the repaired lower fuselage frames mouted back on the jig, with Fuselage Frame #9 being closest to the camera. All of these frames are original to B-22. Note, however, that only the left half of Fuselage Frame #10 was in place, since the right half was still under restoration at the time this image was captured. It has been completed in the interim since, of course. (image via Pioneer Aero Ltd.)
Internal Structure:
Pioneer's William Lowen removed the internal structure from the SBD's lower rear fuselage as a single unit during the disassembly process in spring 2025, placing it in storage until quite recently. This structure supports the battery and various radar and radio components. It extends between Fuselage Frames #9 and #11, so once those frames were restored to flightworthy condition, it became practical to begin working on the internals as well.
The image below shows the internal structure from inside B-22’s lower aft fuselage soon after its retrieval from storage for rework. For reference, the edge closest to the righthand side of this image attaches to the rear face of Fuselage Frame #9, whilst the middle of the structure connects with Fuselage Frame #10. The edge seen at lefthand side of the image joins the forward face of Fuselage Frame #11.
As for the individual components seen here, the octagonally-shaped tray towards the lower left corner of the image serves as the battery mount. The radio receiver sits atop the two channels seen just above the tray, whilst the radio transmitter sits on the channels forward and to its right. Meanwhile, the antenna switch unit sits atop the shelf forward of the battery tray; this marked a change from earlier SBD variants, which did not feature such a shelf—the area beneath it serving as a tool compartment instead (repurposed in the SBD-5). Note, the black paint visible around the battery tray was specially designed to help protect the structure should any acid leak from the battery.
One of the radio rack support rails (forward face) which straddles Fuselage Frame #10 in the SBD’s lower rear fuselage. At the time this image was captured, it had been partially bead-blasted to allow an initial inspection, which showed that it was restorable. As a result, the part will be fully bead-blasted, with minor damage then being treated for a return to airworthy condition. (image via Pioneer Aero, Ltd.)
The opposite side of the radio rack support rail shown in the previous image. (image via Pioneer Aero, Ltd.)
Original parts from the internal structure in B-22's lower aft fuselage following paint stripping and minor damage repairs. The component from the repurposed tool compartment presented in the previous image is seen at the left, whilst the piece which comprises its aft face is seen at the lower right. At the top right we can see a diaphragm section for the righthand side of Fuselage Frame #11. These three parts were ready for primer-painting at the time this image was captured. (image via Pioneer Aero, Ltd.)
Another view of B-22's original, repurposed tool compartment following paint stripping and minor damage repairs. For reference, the inboard side is visible at image left, whilst the bottom face is to the right. (image via Pioneer Aero, Ltd.)
Update (February 3, 2026):
Nigel Lowen continued working on B-22's original radio/radar rack structure and the repurposed tool compartment in the aft lower fuselage during January. Most of the latter is now fully-riveted together, as are two of the radio rack rails. He has also worked on a range of smaller items from the structure like pulley brackets, doublers, and gussets which attach to the radio rack rails and main structure in this area.
