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.
I received a sheet of titanium that will become the firewall shield. I plan to put a couple of layers of fiberfrax between the titanium sheet and the fiberglass firewall bulkhead as an additional thermal barrier. This combination will buy valuable time if the worst-case engine fire should occur.
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.
The bags of parts I received from the factory are in no apparent order and are poorly marked, if marked at all. In addition, the part numbers in the manual frequently don’t match up with the part numbers on the part. This has led to a lot of time searching for a needed part and confusion over whether I am using the right one. So I decided to go through the manual, match up the parts by function and try, by process of elimination, to associate the hardware with the section of the build manual. What I found was that I was missing several parts, and that I also had several parts that I could not associate with passages in the manual.
After discussions with Chad at the factory, I learned that there have been a handful of engineering changes to the kit that have made it deviate from the build manual. For example, the side-stick option eliminates several parts from the kit, but adds many more. There is a small section of the manual for the side-stick option, but there are no photos or drawings to guide assembly or connection. In addition, the factory is trying to get away from using push-pull cables. I was given two push-pull cables in my kit, but it turns out that these are superseded by a new design that uses all solid tubes to connect the aileron torque tube bell crank from the aft keel to the aileron bell cranks on the wing. There are no drawings or documentation for these parts or their assembly…….
All parts were organized, bagged, and labelled, and then stored on a new shelf by the chapter of the build manual. Some rearrangement of the shop was required to fit the new shelf, and this gave me an opportunity to remove a bunch of wood and metal parts that have been accumulating over the years. A net win!
With the holidays approaching, and lots of work around the house required to get ready for visitors, I decided to tackle an easy task – the front seat hard points. First, the aluminum parts were sanded to remove sharp corners and edges. Surfaces were rough-sanded to promote bonding. A tap was run in the threads to clean out debris, and the parts were washed thoroughly with solvent and wiped dry. Inside layer of fuselage and inner foam was removed on the outside positions, and the inner positions were marked. All were set and leveled into structural epoxy + flox + cabosil and left to cure. The next day, a fillet of epoxy + cabosil was used to fill and fair around the aluminum, and covered with 2x bid.
Landing light opening was cut out using jigsaw and sanded to contour with a flange that will later hold the landing light lens. The landing light housing (pre-fab part) was cut to fit and sanded, and bonded into place with a mixture of structural epoxy, cabo, and flox.
The NLG access cover was sanded and duct tape was placed around the opening in the keel where the cover will go. The cover was then hot-glued into place, and layers of BID were applied to make a flange. After curing, the flange was timed and edges sanded smooth.
The circular access hole for the NLG hydraulic cylinder was cut in the keel. The center was displaced about 1.5″ forward and down from plans due to suggestion from Chad. The keel outer skin was then cut back and additional 1/2″ with a rabbet router bit. Foam was dug out in preparation for filling with micro and 2xBID around the edge of the hole.