Center Section Rebuild: Progress Summary

With few exceptions, an aircraft’s wing center section is the most complex structure in the entire airframe. This is certainly true for the Douglas SBD Dauntless; restoration of its center section has absorbed considerable energy from Martin Hedley's team at Pioneer Aero Ltd. in Ardmore, New Zealand. Since Pioneer mounted our SBD's center section in a massive, custom-built jig in October, 2023, they have carefully worked their way forwards from the trailing edges, removing, then restoring or remanufacturing each component as they progressed. As each part returned to airworthiness, Hedley's team trial-fitted it onto the jig to ensure that it nested properly against adjacent original parts before moving on to the next bulkhead or spar needing their attention. As of July 1, 2024, they had made it as far as Spar #3, which is roughly half way towards the leading edges (under concurrent restoration).

Remanufactured SBD Wing Center Section Stringers plus the originals
The top hat stringers (two originals and their replacements) which attach to the upper skin panel between Spars #4 and #5 in the wing center section. Each of the replacements has been drilled to match the skins they mount to. The freshly-remanufactured example in the foreground has also had its ends tapered, as per the original behind it. Another of the two replacement stringers is just visible running along the middle of the image. Note the diagonal line inked along the end marking where the taper cut will travel so it matches the original example to its rear. (Image via Pioneer Aero Ltd.)

Trial Fitting Spar #4, Ribs and Skin Sections:

During June, Hedley's team tapered each end of the 'top hat' section stringers which sit on the upper skin panel between Spars #3 and #4. They used a milling machine to grind away the excess metal until the stringer profiles matched the specifications outlined in the original manufacturer's drawings. The dimensions were also verified against the original surviving components before any machining took place.

With a good number of the components between Spars #3 and #5 restored or remanufactured, it was time to begin trial-fitting them into the center section jig. Spar#3 (and much of the structure forward of it) remains in its original position. It served as an ideal mounting point for precisely positioning the rebuilt structure aft of it.

The team clecoed the replacement upper skin to its attachment points along the tope side of Spar #3, and refitted the rebuilt Spar #4 as well. This allowed the inter-spar ribs lying between them to be fitted and drilled off against the spars and top skin.

Trial Fitting the SBD's newly refurbished wing center section parts aft of Spar #3
Trial fitting the refurbished structure aft of Spar #3. This image shows the underside of the center section with a view of the replacement inter-spar ribs (left side) linking Spar #3 and #4 together. The lower edge of the restored Spar #4 and its interconnecting structure is also visible near the top of the image. Note also that the remanufactured upper skin panel is in place, along with the replacement top hat section stringers described earlier. The tapered stringer ends are clearly visible, indicating that the structure depicted is close to where the center section mates up with the lefthand outer wing panel. (Image via Pioneer Aero Ltd.)

Small Parts Restoration:

In addition to trial-fitting and back-drilling Spar #4, the upper skin panel, and the inter-spar ribs, Martin Hedley’s team also worked on a number of small parts for the SBD’s wing center section. Some of these items included a pulley bracket for the bomb release cables,  a fuel tank selector mounting bracket, the aileron servo mounting bracket, and four rudder cable pulley brackets, along with a variety of other small brackets and supports. Most of these components required refabricating due to excessive corrosion, however some items remained sufficiently intact for restoration to airworthy standards. Each of the components listed above, after either remanufacture or refurbishing, received a coat of primer paint to prepare it for installation in the airframe.

The SBD's bomb release pulley and its remanufactured replacement
The original bomb release pulley (on the right) and its remanufactured replacement (on the left). Note the corrosion on the original beside the center mounting point. The upper spacer also has a long crack in it due to corrosion on the mounting bolt expanding into its interior body. This particular component sits on the upper skin between Spars #2 and #3. (Image via Pioneer Aero Ltd.)
Restored SBD supports for the rudder heel guides
The restored (original) front supports for the rear rudder pedal heel guides. These are mounted on the upper surface of the center section at Spar #3. (Image via Pioneer Aero Ltd.)
The replacement mounting bracket for the chemical tank valve during trial-fitting inside the center section between Spars #2 and #3. (Image via Pioneer Aero Ltd.)
The replacement mounting bracket for the chemical tank valve during trial-fitting inside the center section between Spars #2 and #3. (Image via Pioneer Aero Ltd.)