Center Section Skin Panels:
Over the past several months, the team at Pioneer Aero has removed several skin panels from the SBD’s wing center section. They started at the trailing edge, detaching the flap bay, and have progressively moved forwards from the rear spar (Spar #5) through to Spar #3 on the underside of the airframe.Â
Towards the end of May, the team began working on the top side of the wing center section, with Craig Cunha organizing the effort to carefully drill off the upper skin panel from between Spars #3 and #5. Sadly, as the images reveal, the skin section showed signs of significant corrosion damage at numerous locations, rendering it beyond salvage. Despite this setback, the skin was sufficiently complete to serve as an accurate template for manufacturing its replacement.
Stringers:
The skin panel featured two stringers between Spars #3 and #4, but these were also too badly corroded for reuse; new parts were fabricated as a result. The replacement stringers were then drilled off against the skin so ensure their correct alignment.
Inter-Spar Ribs:
With the skin panels removed from both top and bottom, it was then time to detach the underlying inter-spar ribs spanning Spars #3 and #4. Rather frustratingly, these components were also too corroded for re-use, and had to be rebuilt from scratch. New pulley brackets and p-clip tabs for attaching plumbing and electrical conduits to the ribs were also refabricated. The ribs and their associated components were then prepared and painted with primer after which they were riveted together.
This is the outer face of the rib at Station 15 (left side) which sits between Spars #3 and #4. (For reference, the bottom edge of the component in this image mates with Spar #3.) Sadly this part has corrosion damage beyond airworthy limits, especially around the pulley mount. (Image via Pioneer Aero Ltd.)
This is the outer face of the rib at Station 15 between Spars #3 and #4 from the opposite side of the wing center section to the component in the previous image. The side mating to Spar #3 is also at the bottom of the image. Sadly, again, the corrosion damage is beyond airworthy limits - especially around the pulley mount on other side of rib and at a spot in the middle. (Image via Pioneer Aero Ltd.)
This is the inner face of the rib at Station 33 (Left side) which sits between Spars #3 and #4. (Spar #3 mates along the edge at the bottom of the image). Again, the corrosion damage is beyond airworthy limits, especially due to the galvanic action between the steel fasteners where they mated with the aluminum rib, and along the lower flange where moisture gathered. (Image via Pioneer Aero Ltd.)
This is the inner face of the rib at Station 33 (Right side) which sits between Spars #3 and #4. (Spar #3 mates along the edge at the bottom of the image). Again, the corrosion damage is beyond airworthy limits, especially due to the galvanic action between the steel fasteners where they mated with the aluminum rib, and along the lower flange where moisture gathered. (Image via Pioneer Aero Ltd.)
This is the outer face of the rib at Station 15 LH which sits between Spars #3 and #4. Spar #4 mated with the line of rivet holes at the right of the image. Corrosion damage around the pulley mount is beyond airworthy limits. Note also that the bolt head holding the pulleys in place is utterly been engulfed by a dome of rust, while the bolt head closest to the face of the rib looks untouched by rust and, indeed, is still covered in paint. (Image via Pioneer Aero Ltd.)
This is the outer face of the rib at Station 49 LH which sits between Spars #3 and #4. Spar #3 mounted along the top edge of the part as shown in this image. The corrosion damage is again beyond airworthy limits, especially where the steel fasteners have reacted with the rib’s aluminum structure and along the lower flange. (Image via Pioneer Aero Ltd.)
This is the outer half of the original rib at Station 15 RH after bead blasting. Its replacement is in the process of being fabricated at image right. Pioneer’s engineers fashioned the rib’s MDF forming block so that it fitted exactly into the original rib. New 2024-T3 material in the correct shape is placed between the forming blocks, the aluminum edges which extend beyond its edges are then beaten over to create flanges for the part. Following the forming process, all of the holes and cutouts were added to the new part. It was possible to use the same blocks for each of the replacement ribs between Spars #3 and #4 because the two spars run parallel to one another over the center section. (Image via Pioneer Aero Ltd.)
These components are all awaiting primer painting; the blue plastic will be removed before that happens. Almost everything you can see here - the two halves for the Station 15 (LH) rib which sits between Spars #3 and #4, the pulley brackets and p-clips tabs - is newly fabricated. The two original parts returning to service include the doubler ring and the extrusion. (Image via Pioneer Aero Ltd.)
This is the inner face of the replacement rib straddling Spars #3 and #4 at Station 15 RH. Spar #3 will mount along the left edge of the photo. The pulley bracket and p-clips tabs (other side) have also been newly-fabricated. The original doubler ring around the biggest hole and the extrusion along the edge for attaching to Spar #3 are serviceable. The latter still need to be match-drilled to the new rib. (Image via Pioneer Aero Ltd.)
This is the inner face of the replacement rib straddling Spars #3 and #4 at Station 33 RH. The extrusion spanning the large lightening hole is for attaching the p-clips which hold plumbing in its correct location. (Image via Pioneer Aero Ltd.)