Forming blocks for the remanufacture of some of the ribs which lie between Spars #1 and #2. The outer dimensions of these blocks were determined by using a combination of 3D-scanning the original, non-airworthy ribs and the ordinates provided via the original factory drawings. (image via Pioneer Aero Ltd.)
Forming blocks for the remanufacture of some of the ribs which lie between Spars #1 and #2. The outer dimensions of these blocks were determined by using a combination of 3D-scanning the original, non-airworthy ribs and the ordinates provided via the original factory drawings. (image via Pioneer Aero Ltd.)

Overview:

Impact and/or corrosion damage rendered most of the inter-spar ribs between Spars #1 and #2 beyond airworthy repair. Pioneer Aero’s Hadon Smith has therefore had to remanufacture them. Using a 3D scan of original ribs in combination with the wing ordinate figures outlined in the original manufacturing drawings, he was able to create the necessary forming blocks to accomplish this task. Most of these blocks were relatively straightforward to create, since the circular lightening holes in the completed rib could be formed afterwards with a common flanging tool. However, the rib at Station 10L (i.e. 10” left of the aircraft’s centerline) required extra work, since its lightening hole is triangular in nature. Smith therefore incorporated an appropriately-shaped pressing element into its forming block to achieve the desired result. Thankfully its mirror image at 10R was in restorable condition, so it will be reused. Once each rib had received its basic shape, Hadon then set about positioning and match-drilling any of the assembly’s reusable attaching clips against it. He fabricated replacement clips for any which proved unserviceable. With these tasks completed, Smith then set about cutting through-holes into the ribs, where necessary, for the passage of stringers, pipework, cables and/or wiring. These ribs and their accompanying brackets are now ready for primer painting.

The basic shape for the rib at Station 10L after fabrication. Note the triangularly shaped interior lightening hole which has been pressed into the aluminum using a custom-made forming tool. (image via Pioneer Aero Ltd.)
The basic shape for the rib at Station 10L after fabrication. Note the triangularly shaped interior lightening hole which has been pressed into the aluminum using a custom-made forming tool. (image via Pioneer Aero Ltd.)

At top, we can see three original SBD interspar ribs which lie between Spars #1 and #2 at (from l to r) Station's 10L, 0 and 10R. Their newly fabricated replacements lie immediately beneath them. The original ribs at 10L and 0 clearly have impact damage, whilst the other initially appeared viable. However, following bead-blasting, it became evident that corrosion had taken too great a toll, rendering it beyond airworthy repair. (image via Pioneer Aero Ltd.)

The original ribs (top) which sit between Spars #1 and #2 at Stations 19L and 19R, and their newly-fabricated replacements (bottom). The original righthand rib (top right) clearly received significant structural damage during the SBD's wartime crash, whilst the other possessed too much corrosion to be reused. This image shows the new ribs after their basic outer profile has been shaped in the forming blocks, and the circular lightening hole pressed in using flanging tool. (image via Pioneer Aero Ltd.).

At top we see the original interspar ribs which sit between Spars #1 and #2 at Stations 32L and 32R, with a newly-fabricated replacement for the rib at 32L sitting immediately below it. The original rib for 32L (left) had substantial corrosion damage, whilst its opposite number from the right side of the Wing Center Section had only minor, repairable corrosion issues. The latter original rib is now airworthy. (image via Pioneer Aero Ltd.)

The replacement interspar ribs for (l to r) Stations 10L, 0 and 10R following heat treatment and trimming. The ribs have also been refitted with their attaching clips, most of which are original to B-22. Note that the ribs have also had portals cut into them for the passage of stringers, cables and/or pipework. (image via Pioneer Aero Ltd.)

The replacement interspar ribs for Stations 19L and R following heat treatment and trimming. The ribs have also been refitted with their attaching clips, most of which are original to B-22. Note that the ribs have also had portals cut into them for the passage of stringers, cables and/or pipework. (image via Pioneer Aero Ltd.)

The nearly completed interspar ribs for (l to r) Stations 32L and 32R, with the latter being of original manufacture. Rib 32L has now been heat treated and trimmed, with portals cut into it for the passage of stringers, pipes and cabling where necessary. At the time this image was captured, both ribs were in the process of having their attaching clips riveted in, most of these being original to B-22. (image via Pioneer Aero Ltd.)
The nearly completed interspar ribs for (l to r) Stations 32L and 32R, with the latter being of original manufacture. Rib 32L has now been heat treated and trimmed, with portals cut into it for the passage of stringers, pipes and cabling where necessary. At the time this image was captured, both ribs were in the process of having their attaching clips riveted in, most of these being original to B-22. (image via Pioneer Aero Ltd.)