Overview:
Pioneer Aero has continued working on the upper fuselage over the past couple of months, moving steadily forwards from the rear. With restoration of the aft structure already well advanced, it was time to begin the same effort for the forward area between Frames #1 and #7.
Moving Forwards:
Pioneer’s William Lowen began this endeavor by first removing the upper sections of Frame #7. Sadly each of these two parts was corroded beyond reuse, so Lowen had to remanufacture them. Due to their complex curvature, he opted to make the forming block for these parts out of steel. He then pressed new parts out of blanks made from appropriately gauged 2024 T-0 aluminum sheet. These components are now heading out for heat treating to bring them up to the necessary T-3 tensile strength.
The forward face of the fuselage Frame #7 component shown in the previous image. Corrosion is clearly evident at the top of the frame, but Pioneer decided to bead blast this face to determine the severity of this damage. (image via Pioneer Aero Ltd.)
A view of the Frame #7 component shown in the previous image following bead-blasting. Unfortunately the corrosion was too deep to render airworthy repairs. (image via Pioneer Aero Ltd.)
Both upper halves of fuselage Frame #7 required replacement due to excessive corrosion. This image shows the steel forming block (left) and its backing block (2nd from left) alongside the newly-formed left and right upper halves for Frame #7 (right). Pioneer chose to make the forming block from steel due to the complex nature of Frame #7’s shape. The newly-formed components are now ready for heat treating. (image via Pioneer Aero Ltd.)
Direction Finder Deck
Early model SBDs came equipped with a Bendix DU-1 Radio Compass navigation device, often referred to as a Direction Finder. This equipment was mounted in the rear cockpit on a shelf (aptly named the Direction Finder Deck) immediately behind the rollover structure. Later Dauntless variants, from the SBD-4 onwards, deleted the DU-1, but retained Direction Finder Deck pretty much as designed, using it to accommodate other equipment instead. This component was amongst the items which William Lowen recently removed from the Museum’s SBD and began restoring. The Deck has a small tray at its center. Lowen was able to save the majority of its base, although he did have to cut out and patch a section where corrosion had set in around the instrument light mounting holes. He refabricated the side ribs as well.
B-22's Direction Finder mounting tray during its restoration. While the side rails for the tray needed replacing (see the new metal), the tray itself was in good condition except for one small area of corrosion. The corroded section was cut out and repaired with a doubler and insert patch. This image shows the assembly following repairs while it awaits final riveting and primer-painting. For reference, the front of the aircraft would lie at the top of this photograph. (image via Pioneer Aero Ltd.)
The underside of B-22's Direction Finder mounting tray following its restoration. Note the newly-fabricated doubler (with insert patch beneath) towards the bottom of the part. These repairs replaced corroded metal cut from the tray. (image via Pioneer Aero Ltd.)
An example of a Bendix DU-1 Radio Compass along with its rotateable, loop antenna. Early model SBDs featured this kind of device in their rear cockpit. This particular example belongs to the Smithsonian's National Air & Space Museum. (image via National Air & Space Museum)
Upper Longerons
After working on the Direction Finder Deck, Lowen then began the process of removing the remaining upper longeron sections from the fuselage. These longerons comprise a major part of the fuselage’s rigidity, which means that many ancillary components attach directly to them. To release the longerons, therefore, Lowen essentially had to disassemble much of the remaining original forward fuselage. This included removing the remaining skins and the rollover structure - as the following images will reveal.
A view of the upper fuselage following the removal of the remaining righthand skin panel, seen here sitting on the hangar floor. The process of exposing the longerons was well under way at the time this image was captured. (image via Pioneer Aero Ltd.)
This image shows the upper longerons running along the top side of the fuselage frame. They are still held in place by the rollover structure. (image via Pioneer Aero Ltd.)
A close up showing the righthand upper half of fuselage Frame #6 and the associated longeron (running horizontally at the top of the image). Note the corrosion exposed during the skin’s removal. (image via Pioneer Aero Ltd.)
A view of the upper fuselage looking from the front lefthand side. All of the remaining skin panels have been removed, along with fuselage Frames #1,2 and 3. However, at the time this image was captured, the upper longerons were still held in place by some of the rollover structure. (image via Pioneer Aero Ltd.)
The lefthand side of the rollover structure is seen here during the process of drilling off rivets from the side plate. The side plate’s lower edge straddles the upper longeron, trapping it in place, hence the need for its removal prior to freeing the longeron. (image via Pioneer Aero Ltd.)
With the removal of the rollover structure’s lefthand side plate, only the cover plate between the four uprights is holding the upper longeron in place. However, the rear two uprights (towards the right of the image) must be drilled out before that too can be removed. (image via Pioneer Aero Ltd.)
Rollover Structure
After removing the rear uprights from the rollover structure, Lowen then set about detaching the rest of it. While some of this structure was beyond repair, he was able to salvage a good deal of it, including major fittings and the aft uprights. The following images show some of the results of this effort.
The front half of the rollover structure following its removal from the fuselage. The fittings which join the two sections together at the top will be unbolted from each other and then drilled off their respective extrusion sections. This allowed the complete inspection and appraisal of each part regarding its future airworthiness potential. (image via Pioneer Aero Ltd.)
A closeup showing the rollover structure fittings described in the previous image. The image was captured during the process of removing the attaching bolts. Note the two cut-off bolts just below the fittings; these once held the upper edge of the armor plate which sits behind the pilots seat. (image via Pioneer Aero Ltd.)
The four fittings described in the previous image following their removal from the rollover structure and subsequent bead blasting. The pair to the left lie on the forward face. These components are all in excellent, airworthy condition and merely await a fresh coat of primer before they are ready for reinstallation on the airframe. (image via Pioneer Aero Ltd.)
A reverse side view of the four rollover structure fittings from the previous image reveals their near-perfect state of preservation. (image via Pioneer Aero Ltd.)
Inspection of the aft rollover frames following their removal from the airframe and bead blasting revealed that, other than some minor corrosion where the side cover triangles rivet, they were in excellent overall condition. The approved repair scheme for the damage involved milling away the corroded area to a constant depth and then fitting a flush insert. Here we see one of the parts during the milling process. (image via Pioneer Aero Ltd.)
A close up of of the righthand aft rollover frame following the milling process to remove corrosion. The thin aluminum strip lying atop it is the newly-manufactured flush-fitting insert which will build up the component’s thickness to the correct dimension. (image via Pioneer Aero Ltd.)
A view of the two aft rollover frames following repairs. With the minor corrosion milled away to a constant depth, flush-fitting inserts have been manufactured to build the parts back up to the correct thickness. This close up shows the lower ends of the inserts where the side cover triangles rivet on. (image via Pioneer Aero Ltd.)
A complete view of the aft rollover frames following repairs for minor corrosion. The parts are now ready for primer-painting. (image via Pioneer Aero Ltd.)
The Remaining Fuselage Frames
After detaching the rollover structure, William Lowen then removed the remaining parts from the forward upper fuselage. This included several fittings, along with Fuselage Frames #2, #4, #5 and #6. While Fuselage Frame #2 was too corroded to reuse, Lowen was able to refurbish the others, as the following images will reveal.
The the major fittings from the split line for Frame #5 following their removal from the upper rear fuselage. Note that the fittings are still attached to the ribs, which sit horizontally on the airframe and run forwards to the aft face of Frame #4 and the forward rollover frames. (image via Pioneer Aero Ltd.)
The major fittings described in the previous image following their removal from the adjoining rib structure. They have already undergone bead blasting to remove dirt, old paint and minor corrosion. Inspection revealed that these parts are in excellent, airworthy condition. They merely await a fresh coat of primer paint before they can be reinstalled in the airframe when it goes back together. (image via Pioneer Aero Ltd.)
The aft face of Frame #4 soon after its removal from the rollover frames. While several corrosion spots were evident, further inspection was required before making any decisions regarding its future airworthiness potential. Note, the lighter colored strips reveal where the roll over extrusion attaches. (image via Pioneer Aero Ltd.)
The aft face of Frame #5 soon after its removal from the upper rear fuselage jig. While several corrosion spots were evident, further inspection was required before making any decisions regarding its future airworthiness potential. (image via Pioneer Aero Ltd.)
These two frames have been bead blasted and inspected. The aft face of Frame #5 (bottom) and forward face of Frame #4 (top) following media blasting. While these components do exhibit areas of minor corrosion, they can both be repaired. (image via Pioneer Aero Ltd.)
This close up reveals some of the corrosion to the forward face of Frame #4. Following assessment, the part was deemed salvageable according to structural repair manual protocols. Once all of the corrosion is removed, a sufficiently sized doubler will be riveted over the damaged area to rebuild its strength to the appropriate level. (image via Pioneer Aero Ltd.)
The forward face of Frame #6 following its removal from the upper rear fuselage jig. While several corrosion spots were evident, further inspection was required before making any decisions regarding its future airworthiness potential. The short section of corroded steel tubing protruding from the frame on the right side of the image is all that remains of the lower mount for the rear cockpit flight instrument panel. The two square pieces on the top side of the frame are handholds which the rear gunner could use to pull themselves out of their seat. (image via Pioneer Aero Ltd.)
The aft face of Frame #6 following the component's removal from the fuselage jig. Inspection revealed areas of corrosion which could be mitigated via approved techniques. (image via Pioneer Aero Ltd.)
The aft face of Frame #6 after bead blasting and inspection. There are some minor areas of corrosion but they can be repaired. While they are a little difficult to discern, the brass studs which one can see evenly spaced around the frame were used to secure the gunner’s cockpit bag. This bag lined the cockpit to prevent spent machine gun cartridges and links falling into areas where they might cause problems, such as jamming the flight controls. The studs allowed the gunner to open the bag for access to other equipment they used when not manning the guns. (image via Pioneer Aero Ltd.)
The forward face of Frame #2 following its removal from the upper rear fuselage jig. While several corrosion spots were evident, further inspection was required before making any decisions regarding its future airworthiness potential. The long slot at the center of this component is where the pilot's chart board can slide in and out. (image via Pioneer Aero Ltd.)
The forward face of Frame #2 after bead blasting and inspection. Sadly, the areas of corrosion were too extensive to permit airworthy repairs so the restoration team had to fabricate a replacement part. (image via Pioneer Aero Ltd.)
