Overview:

Subsequent to our last report detailing the ongoing effort to restore B-22's lower rear fuselage, Pioneer Aero's William and Nigel Lowen have made significant additional progress. All of the stringers are now airworthy, with a majority of these being repaired originals from B-22. Trial-fitting continued with the external cladding; several original skins from B-22 being retained after repair. In a major milestone, the Lowens also began permanently riveting on internal fittings and newly-made skins to the underlying structure!

Skins:

While the illustration below has appeared in several previous articles on this site, the author chose to repost it here as a quick reference guide for the reader to easily identify which components are being discussed in any particular image caption or text descriptor. That being said, Skins #102 and #103 (mentioned in this article) are not called out in the drawing. This likely resulted from a Dauntless design update occurring after the illustration's wartime publication. Even so, it should be pretty easy for the reader to place these skins in context with their surroundings. Additionally, while Skin #112 is not officially labeled on the drawing either, that seems to have resulted from an accidental omission, given that the panel is visibly depicted between keel Skins #40 and $42.

A drawing from the A-24B Illustrated Parts manual detailing some of the fuselage skins. While this drawing depicts a slightly different layout to the Museum's SBD, most of the Skin numbers mentioned in this article are mentioned here (with the exception of Skins #102 and #103). Note also that while Skin #112 is not directly labeled in this drawing, it is on view lying along the aircraft's keel between Skins #40 and #42.
A drawing from the A-24B Illustrated Parts manual detailing some of the fuselage skins. While this drawing depicts a slightly different layout to the Museum's SBD, most of the Skin numbers mentioned in this article are mentioned here (with the exception of Skins #102 and #103). Note also that while Skin #112 is not directly labeled in this drawing, it is on view lying along the aircraft's keel between Skins #40 and #42.

Trial Fitting Progress:

Pioneer Aero's engineers continued trial-fitting cladding to the SBD's lower rear fuselage in preparation for final assembly, working their way forwards from aft-most bulkhead (Fuselage Frame #17). The two images below show several replacement skins after they had been drilled-off against the relevant fuselage frames and stringers, trimmed-to-size, primer-painted then clecoed back on to the airframe. Final riveting for some of the skins began soon afterwards.

A view of the SBD’s lower rear fuselage in the process of having replacement skins fabricated. Skins #42 and #112 (running along the airframe’s keel) and Skins #37 and #39 on the righthand side had been completed, painted with primer and re-fitted at time this image was captured. This allowed work to continue inside the fuselage and on skins further forward. Note that one of the original, non-airworthy skins (Skin #44) has been fitted temporally to keep the fuselage structure in alignment. (image via Pioneer Aero Ltd.)
A view of the SBD’s lower rear fuselage in the process of having replacement skins fabricated. Skins #42 and #112 (running along the airframe’s keel) and Skins #37 and #39 on the righthand side had been completed, painted with primer and re-fitted at time this image was captured. This allowed work to continue inside the fuselage and on skins further forward. Note that one of the original, non-airworthy skins (Skin #44) has been fitted temporally to keep the fuselage structure in alignment. (image via Pioneer Aero Ltd.)
Another view of the SBD’s lower rear fuselage during the process of fabricating replacement skins. At the time this image was captured, replacement skins #42 and #112 (running along the keel) and #36 and #38 (on the lefthand side) were undergoing trial-fitting. Note the SBD's horizontal stabilizers are on the bench in the background. (image via Pioneer Aero Ltd.)
Another view of the SBD’s lower rear fuselage during the process of fabricating replacement skins. At the time this image was captured, replacement skins #42 and #112 (running along the keel) and #36 and #38 (on the lefthand side) were undergoing trial-fitting. Note the SBD's horizontal stabilizers are on the bench in the background. (image via Pioneer Aero Ltd.)

Tail Gear Support Components:

As already intimated, Nigel Lowen has worked on some of the structure underlying the rearmost skins, especially the tail gear support components between Fuselage Frames #13 and #17. This included the tapered plates, brackets, and gussets (between frames #15 and #17) which transmit loading from the tailwheel truss fittings through the rear fuselage. These plates and gussets are refurbished B-22 originals. While they exhibited some light surface corrosion upon inspection, it was possible to blend that out well within airworthy limits. The brackets, however, were too badly damaged to reuse. Accordingly, the Lowens made replacements, with refabrication data coming from the original examples and Douglas Aircraft manufacturing drawings. The new brackets have been drilled, counterbored and riveted together as per the original design.

A view inside the SBD’s lower rear fuselage showing the replacement skins undergoing trial-fitting. We can also see the taper plates and associated gussets which lie between Fuselage Frames #15 (at image center) and #17 (beyond the top of the image). Restored original components from B-22, these parts transfer the loads between the tail leg truss fittings and the fuselage structure. (image via Pioneer Aero Ltd.)

Another view inside the SBD’s lower rear fuselage, but this time further aft. The original (restored) taper plates and associated gussets which lie between Fuselage Frames #15 (image bottom) and #17 (image top) were also undergoing trial-fitting at this time. The two original B-22 truss fittings (attached to the jig at the top of the image) are corroded beyond airworthy repair, unfortunately, and will need replacing. (image via Pioneer Aero Ltd.)

A closeup inside the SBD’s lower rear fuselage looking aft with the replacement skins fitted. B-22’s original, fully-restored lefthand taper plates (and associated gusset) are attached to Fuselage Frame #16, while the bolted-on bracket at image center is a replacement undergoing trial-fitting. (image via Pioneer Aero Ltd.)

A closeup view of the reverse side of Fuselage Frame #16 shown in the previous image. The replacement bracket at image center holds the same bolt protruding through the bracket opposite it in the earlier shot. (image via Pioneer Aero Ltd.)

Another view inside the SBD’s lower rear fuselage, but this time looking directly aft with the replacement skins fitted. Fuselage Frame #14 is closest to the camera. Fuselage Frame #17 sits on the far side of the tail leg truss fittings (in the opening). Forward of that are B-22’s original taper plates and gussets (fully restored) which lie between Fuselage Frames #17 and #15. These transfer the loads between the tail leg truss fittings and the fuselage structure. Note the lift point fitting just forward of Fuselage Frame #14 at image left. (image via Pioneer Aero Ltd.)

Nigel Lowen’s hand holds an original channel section from B-22 which rivets against the tailwheel truss fittings (upper surface) and both fuselage sides. Unfortunately, areas of deep corrosion prevented its return to airworthy condition, so Lowen refabricated its replacement, which is pictured nearby in the vise. (image via Pioneer Aero Ltd.)
Nigel Lowen’s hand holds an original channel section from B-22 which rivets against the tailwheel truss fittings (upper surface) and both fuselage sides. Unfortunately, areas of deep corrosion prevented its return to airworthy condition, so Lowen refabricated its replacement, which is pictured nearby in the vise. (image via Pioneer Aero Ltd.)

Fuselage Frame #10 Repairs:

For those readers who haven't followed this project from the beginning, Restoration Update No.82 described a lot of the work needed to repair/replace the fuselage frames in the SBD's lower rear fuselage. Pioneer's engineers concluded most of that effort last year, except for the repairs to the righthand half of Fuselage Frame #10, which had a small, crash-related crack in its flange. William and Nigel Lowen recently finished the necessary repairs to this component, riveting a doubler over the affected area and splicing the frame's left and righthand halves together.

A view of the doubler repair riveted onto the righthand side of Fuselage Frame #10. This frame’s lower two sections and their associated splice plate have also been riveted together. (image via Pioneer Aero Ltd.)
A view of the doubler repair riveted onto the righthand side of Fuselage Frame #10. This frame’s lower two sections and their associated splice plate have also been riveted together. (image via Pioneer Aero Ltd.)

Skin Riveting begins!

The Lowens achieved a restoration milestone with the project recently when they started riveting on the first skins to the SBD's lower rear fuselage. They began with the aft-most skins (#36, #37, #38 & #39), riveting them to the structure between Fuselage Frames #13 and #16. Trial-fitting also continued with additional, newly-made skins further forward on the fuselage (#28, #29, #30, #31, #102 and #103). The following images describe the initial progress with this effort.

This image marks a significant moment, having been captured soon after the first external rivets were installed into the righthand side of the SBD’s lower rear fuselage. The two rows of rivets run along Skins #37 and #39, linking them to Fuselage Frames #14 and #15 and associated stringers. Note that the lifting point fitting, identified by its circular hole and square rivet pattern, has also been attached. (image via Pioneer Aero Ltd.)

He we see the SBD’s lower rear fuselage after the first external rivets have been installed into its lefthand side. While still clecoed in places, Skins #36 and #38 show fully-formed rivets linking them to Fuselage Frames #14 and #15, several stringers and the lifting point fittings. (image via Pioneer Aero Ltd.)

This image shows keel Skins #42 and #112 (closest to the camera) during trial-fitting against the SBD’s lower rear fuselage structure. They were later riveted in place after each of the stringers had been final-fitted. (image via Pioneer Aero Ltd.)

Here we see newly-manufactured, bare aluminum Skins #28 (bottom) and #30 (top) during trial-fitting. Replacement Skin #102 is resting atop the jig in the foreground, and about to be clecoed in place. (image via Pioneer Aero Ltd.)

Here we see newly-manufactured, bare aluminum Skins #29 (bottom) and #31 (top) during trial-fitting. Replacement Skin #103 is leaning against the fuselage further back and about to be clecoed in place. (image via Pioneer Aero Ltd.)

William Lowen (standing) and Nigel Lowen (crouching inside the fuselage) are seen here driving the last few rivets needed to attach Skin #36 to the SBD’s lower rear fuselage structure. (image via Pioneer Aero Ltd.)

Another image showing William Lowen (on the outside) and Nigel Lowen (on the inside) installing the last of Skin #36’s rivets. (image via Pioneer Aero Ltd.)

A replacement for the SBD’s Skin #46 is seen here during its fabrication. At the time this image was captured, the Lowens were trimming the skin’s fore and aft edges using the guillotine (which the part is resting upon) to ensure those edges were perfectly straight. (image via Pioneer Aero Ltd.)
A replacement for the SBD’s Skin #46 is seen here during its fabrication. At the time this image was captured, the Lowens were trimming the skin’s fore and aft edges using the guillotine (which the part is resting upon) to ensure those edges were perfectly straight. (image via Pioneer Aero Ltd.)

Repairing Skins #32 & #33:

Most of B-22's original cladding has proven to be beyond airworthy repair, sadly. Each skin panel either suffered too much impact damage during the aircraft's wartime crash, or corrosion sapped its strength during the airframe's subsequent half-century submerged in Lake Michigan - plus another three decades untouched while stored in Pensacola's salt-laden air. So it is always exciting when Pioneer Aero's engineers are able to restore original skins to flying condition. Such was the case with Skins #32 and #33 which sit either side of the SBD's fuselage near the wing root's trailing edge. These skins have a significant compound curve in their makeup, so the restoration team was relieved to avoid having to refabricate them.

While Skin #33 from the righthand side of the airframe had some minor dents and surface corrosion issues, their resolution proved relatively straightforward. Skin #32 had similar problems to contend with, plus another which required more substantive remediation. At some point after the SBD's recovery from lake Michigan, this skin received some abrasion damage. Thankfully, the deeper gouges were confined to a relatively small area which could be cut away, with new material spliced in to replace it. The Lowens were able to blend out the additional, minor scuffs and smooth over the affected area with bonding compound. The following images reveal the process involved with repairing these skins.

The unpainted section here is Skin #32, an original component from B-22, undergoing trial-fitting. The part exhibited minor corrosion (since removed) upon closer inspection along with some small dents (highlighted in black marker) and some post-crash scuffing. After a little panel beating, the dents became a thing of the past, but the scuffing required more substantial repairs, as subsequent images will reveal. (image via Pioneer Aero Ltd.)

Another image of B-22's original Skin #32 during trial-fitting. Note the two areas of post-crash scuffing. Repairing the deeper gouges towards the top of the image required the Lowen’s to cut out the affected area and graft in a section of new skin (with a doubler underneath to hold the splice plate in place). The other visible friction damage on the part was much shallower, so the Lowens were able to blend it out and use body filler to smooth over the surface. (image via Pioneer Aero Ltd.)

A closeup showing the scuff-damaged area of Skin #32 in the process of being repaired; the section to be replaced is outlined red ink (note the deep gouges in the affected area). A doubler was later fabricated to lie beneath the skin, extending from its edge to just beyond the outer-most row of rivet holes. The damaged area was then cut away, with a splice made to perfectly fit where it had once been. The outer two rows of holes visible are for riveting the doubler to Skin #32, whilst the inner-most row are for attaching the splice. (image via Pioneer Aero Ltd.)

Another shot of B-22's original Skin #32 undergoing repair during trial-fitting. Minor dents in the part required a little gentle panel beating, some of them being visible in this image outlined in black ink. Note that the skin splice mentioned earlier is also visible, clecoed to the component near the top of the image. (image via Pioneer Aero Ltd.)

Another view of B-22's original Skin #32 undergoing repair. Note that the damaged area mentioned earlier has been cut away, with a replacement splice clecoed in place against a newly-made doubler out of sight beneath it. (image via Pioneer Aero Ltd.)

After removing some minor surface corrosion and small dents from Skin #33, an original component from B-22, the part was found to be in airworthy condition. It is seen here (without paint) undergoing trial-fitting on the lower rear fuselage. (image via Pioneer Aero Ltd.)

Stringer Repairs:

Many of B-22's stringers from the lower rear fuselage were repairable for airworthy reuse, albeit sometimes with sections of new material spliced in following procedures outlined in the SBD's Structural Repair Manual. Similarly, stringers with sections of minor damage could have a doubler riveted over the affected area to bring it up to the necessary strength. Images in this section of the article illustrate some of the restoration work involved, while also revealing elements of the trial-fitting process too. Note that several more skins are seen in the process of being riveted into place as well.

All of the SBD's lower rear fuselage stringers have now either been repaired or refabricated.

The is the splice repair on B-22's original Stringer #8R (which runs between Fuselage Frames #7 and #13). The forward half of this stringer exhibited significant crash and corrosion damage. Rather than refabricating the entire component, however, Pioneer opted to replace just the forward section, thus preserving as much original material as possible. The repair splice lies between Fuselage Frames #10 and #11. While the rear section of this stringer featured localized corrosion just aft of Fuselage Frame #12, Pioneer was able to effect a repair by blending out the minor pitting then boosting strength by riveting on a section of doubler angle which straddled the affected area. Both of these repairs complied with the standards outlined in the SBD’s Structural Repair Manual. (image via Pioneer Aero Ltd.)

This image shows the reverse side of the splice repair to the original stringer depicted in the previous image. A closer look will reveal the join half way along the attached doubler angle. (image via Pioneer Aero Ltd.)

Here we see the doubler angle riveted to B-22's original Stringer #8R as part of the repair regimen for the small area of corrosion damage on the component just aft of Fuselage Frame #12. As already noted, this repair conformed to the SBD’s Structural Repair Manual requirements. (image via Pioneer Aero Ltd.)

Here is the splice repair on B-22's original Stringer #7L (which runs between Fuselage Frames #7 and #13). While the forward foot or so of this stringer exhibited crash damage, the rest remained in excellent condition. Therefore, in accordance with the SBD’s Structural Repair Manual, Pioneer Aero decided to repair the part by splicing in new material forward of Fuselage Frame #9 rather than replacing the entire component. (image via Pioneer Aero Ltd.)

Here we see the reverse side of the splice repair to B-22's original Stringer #7L depicted in the previous image. A closer look reveals the join half way along the attached doubler. (image via Pioneer Aero Ltd.)

This is an original stringer from B-22’s lower rear fuselage. After bead-blasting, the only remaining damage requiring attention involved the minor twist shown in this image. Thankfully, Pioneer’s engineers were able to remove this kink and return the part to airworthy condition. (image via Pioneer Aero Ltd.)

After trial fitting, the last of the SBD’s lower rear fuselage stringers to receive attention were ready for the paint booth, as seen here. Some of these parts are repaired originals whilst others are replacements. (image via Pioneer Aero Ltd.)

The last repaired stringers for the SBD’s lower rear fuselage’s are seen here (unpainted) during trial-fitting. To keep the parts in position during this process, the Lowens clamped them flat against an extrusion extending temporarily across the bottom of Fuselage Frame #9. They are all parallel from that point forwards to where they meet Fuselage Frame #8 at the wing’s trailing edge. Note, the painted stringers on view had undergone restoration earlier. (image via Pioneer Aero Ltd.)

Another view of the final batch of repaired stringers (unpainted) during trial-fitting. Skin #32 (unpainted), with its repairs underway, is also on view here. (image via Pioneer Aero Ltd.)

A broader view of the repaired stringers (unpainted) during trial-fitting. Also visible are B-22's original Skins #34 and #44. The latter are beyond airworthy repair, but remain in good enough condition to be used to confirm Fuselage Frame and Stringer positions. (image via Pioneer Aero Ltd.)

A view of the lefthand side of the SBD’s lower aft fuselage. At the time this image was captured, several skins were in the process of being riveted to the underlying structure. Skin #28 is the thin, primer-painted panel with its lower edge forming the fuselage seam (just above the jig). Skins #102 and #30 lie above it, with the latter being the short section just below the unpainted panel (Skin #32). (image via Pioneer Aero Ltd.)

This is the righthand side of the SBD’s lower aft fuselage. At the time this image was captured, several skins were in the process of being riveted to the underlying structure. Skin #29 is the thin, primer-painted panel with its lower edge forming the fuselage seam (just above the jig). Skins #103 and #31 lie above it, with the latter being the short section with the perforated blister bulging from it, an original restored component from B-22. (image via Pioneer Aero Ltd.)
This is the righthand side of the SBD’s lower aft fuselage. At the time this image was captured, several skins were in the process of being riveted to the underlying structure. Skin #29 is the thin, primer-painted panel with its lower edge forming the fuselage seam (just above the jig). Skins #103 and #31 lie above it, with the latter being the short section with the perforated blister bulging from it, an original restored component from B-22. (image via Pioneer Aero Ltd.)

Skin Riveting Continues:

With all of the stringers for the SBD's lower rear fuselage repaired/replicated, primer-painted and positioned on the airframe, it was time to attach more of the internal structure and rivet on some of the recently-refabricated, trial-fitted, trimmed and primer-painted skins. This effort began with Skins #36 and #37 and continued with replacement Skins #28, #29, #30, #31, #102 and #103 as the following images reveal.

A view of the arrestor hook shock strut mounting brackets which sit between stingers #15L and #15R on the aft side of Fuselage Frame #12. These stringers and their associated brackets are all original, fully-refurbished B-22 components. Interestingly, the outer faces of these stringers and the fuselage frame’s exterior flange were not flush with one another when B-22 left the factory; creases in the original skin confirm this. Pioneer corrected this error by replacing the joiners holding the stringers in place against the frame with new examples that allowed the latter to lie flush with the frame’s exterior flange. (image via Pioneer Aero Ltd.)

This image shows fairing Skins #32 and #33 (original B-22 components) clecoed to the airframe after their restoration to airworthy condition, trial-fitting and primer painting. Sitting between these two fairings is Skin #46. Newly-fabricated, it is also ready for riveting to the structure. Similarly, and just forward of Skin #46, we can see Skin #92 clecoed to the airframe. Refurbished original B-22 fairing skins (#72 and #73) sit either side of Skin #92. These skins will match up against the Wing Center Section’s trailing edge. (image via Pioneer Aero Ltd.)

Another view of both the restored and replacement skins between Fuselage Frames #10 and #8 (furthest from the camera). The forward edge of Skin #92 (image top) is where the lower rear fuselage subassembly will meet the Wing Center Section trailing edge. (image via Pioneer Aero Ltd.)
Another view of both the restored and replacement skins between Fuselage Frames #10 and #8 (furthest from the camera). The forward edge of Skin #92 (image top) is where the lower rear fuselage subassembly will meet the Wing Center Section trailing edge. (image via Pioneer Aero Ltd.)
A view inside the SBD’s lower rear fuselage looking aft, with Skin #92 in the immediate foreground at the top of the image and Skin #46 just to its aft. Both newly-made skins are ready to be riveted to the underlying stringers and fuselage frames. (image via Pioneer Aero Ltd.)
A view inside the SBD’s lower rear fuselage looking aft, with Skin #92 in the immediate foreground at the top of the image and Skin #46 just to its aft. Both newly-made skins are ready to be riveted to the underlying stringers and fuselage frames. (image via Pioneer Aero Ltd.)

The two brackets (dark green paint) on the lefthand side of this image have been riveted to Stringer #7L between Fuselage Frames #9 and #11. The radio racks will be mounted against these brackets. (image via Pioneer Aero Ltd.)

A view of the opposite side of the fuselage to that shown in the previous image revealing that the two righthand brackets for the radio rack have been riveted to Stringer #7R between Fuselage Frames #9 and #11. (image via Pioneer Aero Ltd.)

The two large, bare-aluminum forgings seen here are the replacement mounting brackets for the SBD’s tail gear. They have been drilled to match B-22’s original lower mounting stiffeners seen at the top of this image. (image via Pioneer Aero Ltd.)

The SBD’s replacement tail gear mounting brackets are seen here just inside the aft end of the airframe. They are bolted to a positioning guide on the assembly jig. Note the small curved strip of rough-looking sheet metal clecoed to the fuselage exterior; this is the original doubler which supports the hard rubber arrestor hook bump stop. It will be replaced in due course. (image via Pioneer Aero Ltd.)

Arresting hook Bumper Refabricated:

Much like many US-designed WWII-era naval aircraft with deployable arrestor hooks, the SBD features a rubber bumper on the fuselage exterior to prevent the tail hook from marring the skin where it rests against the fuselage when stowed. While B-22's original bumper survived intact, the material had perished considerably, so the part had to be refabricated. Pioneer Aero executed this task by first making a mold in the correct shape, and then pouring in a two-component resin mixture which solidified to form the new part. Happily, the Lowens were able to return some of the bumper's original fuselage attachment strips to airworthy condition.

Towards the top of this image we can see B-22's original rubber arresting hook bumper. Sadly the rubber was perished beyond airworthy reuse, so Pioneer fabricated a replacement (seen immediately below it) using a two-part urethane compound poured into the mold at the bottom of the image. At image right are the three fully-restored, original aluminum strips which clasp the bumper’s sides and leading edge. (image via Pioneer Aero Ltd.)
Towards the top of this image we can see B-22's original rubber arresting hook bumper. Sadly the rubber was perished beyond airworthy reuse, so Pioneer fabricated a replacement (seen immediately below it) using a two-part urethane compound poured into the mold at the bottom of the image. At image right are the three fully-restored, original aluminum strips which clasp the bumper’s sides and leading edge. (image via Pioneer Aero Ltd.)