Scott Swing let me know that the engine mount for a TCM IO-550 is 24″ wide at the bottom, and that the bolts penetrate the firewall just above the fuselage floor. I had previously cut down my header tank to make more room in this area, and I was relieved to find that there appears to be sufficient space to accommodate the bolts and the large washers. The 12″ mark is aligned with the fuselage centerline, and the tape measure shows the approximate location where the holes will be.
The landing gear hydraulic pump was mounted onto the MLG bulkhead with a thick aluminum backing plate. Bolts enter from the aft side, pass through the backing plate, and then screw into the hydraulic pump body. The pump reservoir is about 2 cm off the floor of the fuselage.
After making a couple of flexible hydraulic lines that run from the pump to the fittings on the MLG hydraulic cylinder, I started to worry about the hydraulic lines fouling the MLG retraction cables. One solution would’ve been to fabricate rigid hydraulic lines, but I decided to separate the keel space vertically into an upper deck and a lower deck. The brake lines, which are rigid tubing, and the MLG cables will occupy the lower deck, an the aileron torque tube, hydraulic lines, and wiring will be on the upper deck. A thin layup was made with 2x BID on aircraft plywood, and this was shaped to be the divider. An aluminum tunnel was made to cover the aft end of the gear cables, and to provide a transition for the hydraulic lines to enter the keel.
An aft battery tray was fabricated as a layup of 1x triax and 2x BID on divinylcell foam. The layup was done directly on a glass plate to get a smooth top finish. The tray and the legs were cut out with a jigsaw, and the legs were contoured until the tray sat level in the aft area between the whale tail and the MLG bulkhead. An aluminum battery bracket is being fabricated to retain the battery to the tray and to the MLG bulkhead.
The aileron torque tube sections, the universal joint, and the rear torque tube bell crank have to be drilled so that the sections and parts will mate together tightly and in proper alignment. I used the wing spar and firewall as a table and clamp plate, respectively, to hold the assembled torque tube in position for drilling the last hole through the torque tube bell crank. The torque tube bell crank and the forward side-stick bell crank have to both be aligned vertically when attached. Its a kluge, but it worked OK. The holes were drilled slightly undersized, and then reamed for an interference fit for the AN-3 bolt. Slop is unacceptable.