Spar Removal:
Recently, Pioneer Aero’s engineers successfully trial-fitted the newly-manufactured wing center section skins which mate up with the rear spar (Spar No.5) on its upper and lower surfaces. With these skins now aligned properly with the rivet holes on Spar No.5, the team was free to remove this structural member and commence its restoration. Drilling off the remaining rivets attaching the spar to the center section, Craig Cunha and Stephen Fox were able to lift it from the airframe, being careful not to snag this 11’ wide component on any intersecting structure.
Restoring Spar No.5:
Cunha and Fox completely disassembled Spar No.5 into its component parts, bead-blasting then inspecting each item regarding its potential future serviceability. Readers may recall that the lower half of the SBD’s fuselage is built integrally with the wing center section. It just so happens that the lower halves of Frame #7 are riveted to Spar No.5, so these parts were amongst those receiving treatment.
While the spar web, end channels and lower spar cap were too corroded for reuse, Cunha soon got to work fabricating their replacements. Thankfully, the other parts, including the lower halves of fuselage Frame #7, were all reusable and each of these has since undergone restoration to airworthy condition.
The forward face for Spar No.5’s lefthand side revealing two areas of significant corrosion: note the pitting in the web towards the left and right sides of the image. (image via Pioneer Aero Ltd.)
More corrosion pitting (note the white-hued areas) on forward face of Spar No.5’s web. The lower spar cap is at the top of the image. (image via Pioneer Aero Ltd.)
Significant corrosion issues are also visible here in the web material for the righthand aft face of Spar No.5. This, and the other corrosion issues depicted in previous images all combined to render the spar web un-restorable. (image via Pioneer Aero Ltd.)
The original web for Spar No.5 (aft face visible at the top of the image) and the lower spar cap below it suffered insurmountable corrosion damage, some of which can be seen at the left end of the spar web. The replacement spar web (note shiny metal), lower cap and the original upper cap are clecoed together at the bottom of the image. (image via Pioneer Aero Ltd.)
The original end channels for Spar No.5 were too corroded to reuse. They are pictured here sitting below their remanufactured replacements. (image via Pioneer Aero Ltd.)
The lower halves of fuselage Frame #7 following media-blasting and inspection. While these components did reveal some corrosion issues, it was of negligible depth and within the damage limits permitted by the SBD’s wartime Structural Repair Manual. This means these frames are of sufficient quality to permit their restoration to airworthy condition. (image via Pioneer Aero Ltd.)
A close up image showing the minor corrosion issues for Frame #7 components. (image via Pioneer Aero Ltd.)
The lower halves for fuselage Frame #7 after the minor corrosion damage was blended smooth, as permitted by the SBD’s Structural Repair Manual. These areas were bead blasted again to confirm that all of the corrosion had been removed properly, rendering the frames airworthy. (image via Pioneer Aero Ltd.)
