The factory is replacing the push-pull cable aileron linkage with a new pushrod linkage. There are now bell cranks mounted on the landing gear bulkhead that connect directly to the control torque tube that passes through the keel tunnel. These bell cranks transfer motion to two long pushrods that pass through the MLG bulkhead and the firewall, connecting directly to the aileron control surface torque tubes in the engine compartment at the trailing edge of the wings.
The mating surface on the MLG bulkhead had to be filled and leveled to make a good mounting surface for the bell crank mounting bracket. Then holes were drilled through the bulkhead for the pushrods. I now have to figure out some way to determine the position of the corresponding hole in the firewall bulkhead….
In an effort to make a few things look spiffy, I sent a bunch of metal parts to a local shop to be powder-coated. Most of these parts were for the NLG actuating mechanism, the NLG fork, and the NLG shimmy dampener. I also got the aileron bell crank brackets and the MLG leg booties powder coated. My aircraft is going to have black legs – sexy.
I refuse to buy a bunch of the expensive metal flanges for the attachment of SCAT/SCEET hose for heating and cooling. So I bought one each of the two most probable sizes if hose I will be using, and used them as a template to make a mold so that I could replicate them in fiberglass. Mold release wax was used liberally on the metal, and then a liberal layer of cabo on the surface (poor mans gel-coat) followed by 4x bid was laid up on the outside of the metal template to make the mold. I added graphite to the epoxy to make the mold black. After smoothing and filling and waxing, I could punch out replicas of the SCAT hose flanges. I will use these on the various air boxes and ducts for the cabin heating and cooling system.
I think I have decided to use a Continental IO-550 engine. The engine mount bolts for the TCM engines come through the firewall in the lower corners, and the standard header tank interferes with that location. So I have to modify my beautiful header tank by cutting the corners off.
The cut line was marked, and the oscillating tool made short work of the cuts. Two thick lay ups (8x bid) were used to make the new corner walls. These were coated, sanded, and coated with EZ-poxy to form a fuel-tight inside wall, then were bonded to the header tank with a fillet of cabo and 2x bid around the perimeter. New mounting ears were also added.
Taking care of some miscellaneous items associated with the main landing gear. First things first, re-glue and clamp my favorite rocking chair using resorcinol-phenol glue – amazing stuff. Ripple the hangar cat approves. I plan to mount the MLG dump valve inside the keel, accessible by a fold-up door at the pilot’s right armrest, instead of in the inset cutout in the side of the keel. So I made some sheet metal bracketry to attach the dump valve to the inside of the keel wall. Also, the MLG retraction pulley mount was beefed up with a fillet of cabo+flox, followed by a layer of triax. I also ground off the shoulders of the MLG hydraulic cylinder mounting bracket because this was in the way of the hydraulic fittings. Now the hydraulic lines can be installed fore/aft without making sharp bends inside the keel.
I finally received the main landing gear hydraulic cylinder from the factory, over a year late. It was installed in the keel tunnel and the retraction cables were attached to the MLG over-center mechanism. Instead of hooking up the hydraulic pump, I decided to use nitrogen to test the retraction. There is a stored energy problem with using gas, so I was very careful to manually help the retraction through the portions that required the most pressure. I found that the over-center lock bar disengaged at about 380 psi, but it only required about 100 psi to hold the MLG in the retracted (up) position.
There are always things that slow you down, make you scratch your head, or make you shake your head in wonder.
As part of my kit, the factory included some parts that were not labeled, I could not find in the manual, and had no clue what they were. I sent some pictures to Scott S. and he identified them as aileron bell cranks for the V-Twin….. It turns out the V-Twin and the newer XL-RG kits are not using the push-pull cables from the whale tail to the ailerons. They are replaced with solid push rods and bell cranks, and these parts are part of that new system (completely undocumented). Scott quickly got the correct parts to me, as well as a new Atkinson-type aileron trim actuator/spring mechanism to replace the previous cheesy string-belt trim system.
I ordered several 6 foot lengths of 5052-O aluminum tubing from Aircraft Spruce to use for brake lines. The package got mistakenly routed to San Antonio instead of Austin, and it was a few days late arriving at the house. From previous experience, I know that Aircraft Spruce is pretty good about shipping long lengths of tubing taped or affixed to a piece of wood to keep them straight. Never mind that – when my package arrived, all of the tubing was folded in half and stuffed back into half the box, which was now only 3 feet long. The wood stiffener was missing. I can only guess that somehow the box was too long for the guys in San Antonio, so they just shortened it….. I sent the great folks at Aircraft Spruce a photo and they happily sent me another order of tubing.
The rudder cables travel to the rear of the aircraft in Nylaflow tubing that is attached to the top of the cable conduits in the floor of the fuselage. The Nylaflow is held in place with 1x bid, so I used this opportunity to use my new roll of 2″ wide bid tape, just wetting it with Velocipoxy as I worked down the length of the fuselage (both sides).
At the landing gear bulkhead, the Nylaflow tubing passes through a section of aluminum tubing that passes just outboard of the MLG leg and then through the firewall.
The manual calls for beefing up the area where the landing gear bulkhead is connected to the main spar, which is also the area where the MLG leg sockets are. I had already put the foam and 2x bid on the trapezoidal connection between the landing gear bulkhead and the spar, but it needed a layer of glass underneath (tricky clamping) and another strengthening layer on top.
Thick 3x triax layups were placed in the area where the engine mount bolts will pass through the firewall – on both sides of the firewall. I guess I have decided to use a TCM IO-550 engine. The upper triax straps will have to wait until the top is bonded on. Its tedious, but good technique requires removing ~1/4″ of foam from sandwich panels, and then filling it with micro and sanding it smooth after it cures. Some of these joints and tight areas have to be sanded by hand because there is not room for a sander…
Some stiffening layups need to be added to the landing gear bulkhead in the region of the MLG pivot bolts, and in the transition area between the main spar and the firewall. Did a nice fill with epoxy+cabo, plus some flox around the spar area, then some layers of triax around the MLG bolts and bid at the main spar. Added peel ply to keep it neat.