C-GOEZ : Paint, Final Assembly and Rigging

FINAL ASSEMBLY

Even with all the previous talk about preparation and painting, it still leaves a question about how much painting to do before assembling the cabin onto the main frame vs. painting after the panels and pieces have been screwed and riveted in place. In general, I'm choosing to do as much painting as practical before the parts are installed as this allows me to easily check the coverage / quality and to get paint on the various faying edges. More importantly, all the aluminum preparation (i.e. alodine and primer) is done while the panels are easily handled as individual pieces. My general idea is to topcoat wherever possible and to leave the exterior of the cabin sheeting in primer till after all riveting has been done. Hopefully, once the entire cabin has been riveted together then I can apply a bit of primer over the rivets and the outside will then require a sanding of all the primer and just the final topcoat(s).

There are a lot of smaller pieces, such as interior panels and the shroud components, whose painting sequence is not really important other than to get all the pieces done before final bolt-on assembly. Where appropriate, I wet-riveted these pieces with primer into larger sub-assemblies before actually painting them. One exception was the side panels that go between the seats and the door sills; these parts were painted before riveting due to potential difficulties getting into the deep recesses with the spray gun.

What happens when I have too much time waiting for other painted parts to dry/cure

Wherever possible, smaller assemblies were pre-riveted together and various holes have already been drilled/cut and verified. I've chosen to paint the inside of the panels in the cabin area with a single coat of white so as to improve the visibility in the area under/behind the seats when performing maintenance. Because this area is "hidden", it allowed me to practice my painting technique. I'm not sure how others have done their assembly sequence, but I thought I'd share my sequence and reasoning.

I chose to try do as much work on the cabin area as possible without the bubble or boom attached. Leaving the bubble off made for very easy access to various areas when doing things such as the wiring. Once the boom is installed it makes it much more difficult to move the craft around and it also makes for a lot of extra walking around or sliding underneath it. There really is no need to attach the boom until work begins on the tail rotor driveshaft. I also kept the ship on the casters as long as possible ... this made it harder to do some of the engine stuff as it was closer to the ground but it also made it much easier to move the ship around and the lower height was very convenient when working on the transmission and fuel tanks.

Main Frame - The main frame was prepped and then painted. The rotating joints on the pedal assembly and cyclic pivot were first sealed by wrapping a single layer of .020" safety wire around them and I had some plastic plugs inserted into the various tapped holes. Since I had the frame lightly sand blasted, the nutplates were not installed before paint and they were subsequently primed & riveted in place. Tubeseal was introduced into the frame and then it was rotated several times. Considering the complexity of the structure, I'm not sure that all areas received a coating, but hopefully most of them did.
Controls - Before installing any sheeting on the frame, the throttle rod and cyclic / collective system should be prepped, painted and installed. In addition to the exterior surfaces, I also chose to coat the interior surfaces of all open tubes. On the various areas where there is sliding or rotating surfaces, I chose to coat these areas with Perma-Slik G. Final preparation and installation of the cyclic sticks has been deferred until after the seat cushions have been installed so that the required height based on my seat cushions and cyclic grips can be determined. Note that once the rear side sheeting is in place, it becomes much more difficult to install the control system through the firewall area and virtually impossible to do so once the engine is installed.

Note: Once the controls and collective trim spring have been installed, there will be considerable downwards force on the forward end of the collectives / throttles. Any rotation of the throttles while the collectives are down can quickly wear the paint off the contact point on the throttles. Perhaps UHMW tape on the contacting surfaces will delay the wearing off of the paint.
Bottom Sheet - It looked kind of weird, but the bottom panel was primed and the area behind the middle rib was given a white topcoat and the area ahead of the front rib was given a grey interior colour topcoat. Note that both sides of the "lips" also require the colour coat.
Bottom Ribs (Front, Center and Sides) - The center rib was left with just a full primer coat on the front side and a light topcoat of white on the backside. Likewise for the two small side ribs. Because of my heat ducting, there are some difficult to reach rivets on the bottom of the front rib and bottom edge of the heat duct. The front rib was initially only done in primer so the sequence became: rivet front rib to belly pan (the important joint), rivet heat duct to rib and then topcoat the front of the rib. Note that there is just a bit of the area inside of the front rib at the outside edges that may be visible after final assembly; I painted this area with my interior grey colour. The three bottom ribs were riveted to the bottom sheet before any of these were re-attached to the main frame which made for easier access without having to contort around frame members.

Firewall Ribs (4) - The top and bottom ribs were fully topcoated before assembly in order to reduce the masking and difficulty in painting them after assembly. Since there are several rivets in the side ribs that are installed after initial assembly but are visible, I was planning to initially only basecoat the outside of the side ribs. Once the cabin is ready for final topcoat, the side ribs would be exposed in the mask and receive their topcoat which would be relatively easy as there is a natural separation line. Like a lot of plans, this one managaed to change. I was going to pre-paint just the flanges, but by the time I did this there was enough overspray and weird looking effect that I finally just put on a full topcoat. After some experimentation, it looks like I can put a topcoat on just the flush rivets without it looking too obvious since there is a natural line around the rivets. I was very careful when installing rivets on these topcoated parts to use riveting tape on them to avoid marring the surface and any need to repaint the whole part. The safer alternative (from a paint perspective) would have been to use pulled rivets but they aren't as strong.

Note that the throttle torque tube should be installed before the bottom firewall rib is installed. Although it could be installed or removed / installed at a later time, this would require the slot in the firewall rib to be enlarged.
Door Sills - I chose to pre-paint these with my interior grey colour as I figured this would save a lot of masking that would be required if they were painted after riveting. The only large masking job that will be required after the main assembly will be for painting the exterior of the main hull and the entire interior should already be completely painted by then.
Side Sheeting - The large rear side panels received an interior coat of white and the exterior was left in primer. The front chin panels got an interior coat of grey since a bit of the front of them is visible after assembly. The rear door sill was riveted to the sides, but the front door sill was deferred until after the floorboard was installed.

After riveting these pieces and before installing the floorboard, I chose to finalize the locations and drill the holes for my pitot tube and belly COM antenna. Although I have some access to this area after the floorboard is mounted (i.e. enough to tighten the nuts & connections), it's a lot easier to drill and deburr the holes when one has total access to both sides. Although I do have a heated pitot tube available, it will require a special mount to be fabricated so I chose to go with the CHR-supplied one initially just to keep the project rolling along. My final location was about 2-1/2" behind the vertical part of the front rib and I added an inside doubler plate that spans most of this.

The antenna location is a compromise since there is not enough length in the belly pan to provide the ideal clearances for a bent-whip COM antenna and the tranponder antenna. I chose to mount the COM antenna about 22" behind the front lip of the belly pan which is about ideal for forward and sideways radiation. It is slightly off center so that the coax will clear the heater SCEET tube on the inside. The transponder antenna is mounted very far back on the belly pan (just under 3" forward of the trailing edge) and slightly offset to the opposite side from the COM antenna. Both antennas have a doubler plate but I still have a bit of concern about whether there is enough rigidity in the belly pan for the COM antenna ... I may have to eventually add a piece of side-to-side angle to spread the load.
Floorboard, Floor Bins and Switch Console - All riveting was done on these sub-assemblies before installation as was all the painting. Before installing the floorboard, I first installed the SCEET tubing for the cabin heat duct and also drilled the floorboard for the pitot tube and the belly mount antenna pass throughs which will be installed later on. Although parts of the switch console are riveted to the floorboard, the actual switch panel was not installed at this time since it will be pre-wired as much as possible and installed once all painting is complete. Due to maximizing the size of my floor bins, these bins had to be placed in position before the floorboard and then fastened to it during assembly since they cannot be slid in (or removed) at a later time. Note that due to my wider than normal floorboard, the front door sills were not riveted to the side sheeting until after the floorboard was installed.

Once the switch panel and wiring have been installed, it's impossible to remove the floorboard without a major effort. It is possible to put a small bead of RTV sealant or rubber tape between the frame tubes and the floorboard such that any "drumming" would be prevented and/or absorbed by the RTV. Of course, I figured this out and discussed this with another builder after my floorboard became non-removeable (at least without a lot of work). One should also be careful of any of the centerline screws that may be covered by wires later on. In addition to making sure there are no burrs that could cut into the wires, one might want to add some blue thread locker to these bolts so they won't loosen under vibration.
Door Frames(P-channel), corner pieces, eyebrow panels and bubble capstrip - These pieces were all worked on together so that I could do a final tweak on the eyebrow panels before riveting all these pieces in place. The bubble had to be installed then removed but I believe it was the right way to do it since there was some definitely some final changes to the eyebrow panels that I felt could only be done once the side panels had been riveted and locked in place. Once again I learned to curse the eyebrow panels and the difficulty in getting a perfect fit. The door frames and corner pieces were pre-painted so as to get coverage on the ends and to avoid the need to mask for overspray while the eyebrow panels and bubble capstrip were topcoated on the inside and left in primer on the outside. The fact that several of the CHR drilled rivet holes in the P-channel were right against the center of the angle made the riveting much more difficult and hopefully these will not cause future problems.

One issue that I ran into is that the forward-most rivet hole in the eyebrow / P-channel joint is such that the tail of the rivet will actually contact the bubble and I had a concern that in addition to forcing the joint away from the bubble, it would also dig into it and create a stress riser. Before removing the bubble for riveting, I used a sharpie through the rivet hole to mark the bubble where this contact would be. Since this is on the white doubler material on the bubble, I chose to carefully grind a relief in the doubler. When riveting this hole, I chose to use a minimal length rivet and to purposely slightly over buck it to lower the profile. During bubble installation, I will also add a dot of RTV in this relief to spread out the load and dampen any vibrations. Time will tell whether this is still a sound joint.

The door frame corner pieces are extremely soft and their holes were no longer in good shape after the various use of clecos during fabrication. Because I'd dimpled these for flush rivets, this helped somewhat but I also chose to back up all rivets with rivet washers to get a clamping action and hopefully prevent future working of these rivets. There are a couple of difficult to buck rivets on the lower doorsill but I eventually got them all bucked with solid rivets by using a variety of different bucking bars. I cheated on the corner trim pieces and just used pulled rivets.
Exterior Cabin Painting - In preparation for painting the exterior of the cabin, I first used a small brush to put a bit of primer on each of the rivet heads. Because I'm using flush rivets, I've found that this extra primer seems to allow for a better topcoat as it smooths out a bit of the very sharp edge on the rivet head. The pre-primed exterior panels were then sanded with maroon Scotch-Brite after two riveting oopsies were first filled. Note that there is one last chance before exterior paint to do a little "massaging" of some of the panel edges. I found that in a few areas around the door sills the sheeting edges had slightly lifted due to the riveting process. These were easily coerced back into place with careful use of a hammer.

In order to try keep the bubble cap strip in it's final position, I used black clecos (5/32") installed from the inside in the screw holes; the outside two screw holes had cap bolts installed to keep the edges of the eyebrow panels flush during painting. Although the exterior masking requirements are obvious, I chose to also mask the interior side of all the seams since spray paint seems to find the minutest hole to seep through.
After the paint on the cabin had fully cured (about a week), I took a close look at the firewall area and looked at the various openings around the tubes and the deeper flutes in the corners. I decided that there were significant gaps that I wanted to seal and I used Fire Barrier 1000 silicone sealant since I'd managed to find a tube of it locally. I think that a good RTV (possibly high temperature) would do an equally effective job.

At this point, I had to make a decision whether to proceed with the engine installation or the cabin components. Although some of the work is being done in parallel, my emphasis is on the cabin. The reason for this is that the hangar I'm working in is quite dusty due to composites work and I want to get the bubble mounted before doing any of the wiring. I had planned to defer the bubble mounting till very late in the process, but the only thing that becomes really awkward with it installed is mounting the instrument pod. Thus my next priority is to mount the instrument pod and then the bubble. Even before the doors are finalized and hung, I can install the firewall and hang sheets of polyethylene over the door openings to try minimize dust entry.

Before the engine and bubble are installed, it's easy to tip the cabin back to work on the bottom of it. I made sure that I'd done everything I wanted to do before proceeding. Due to clearance issues, the pitot tube and belly antenna mounting are deferred until after the ship is on it's skids, but the short transponder antenna was mounted at this time.
At this point, I also added the "rubber" molding around the front and back of the cabin where it contacts the bubble. This was glued in place using 3M 8011 (black) weatherstrip adhesive which worked quite well for me. I first put the molding in place dry and placed some 1/4" painter's masking tape layed flush alongside it. This allowed me to brush on the adhesive without worrying about getting it where it wasn't wanted. By waiting to remove the tape until after the molding was installed, I was also able to remove with ease any excess adhesive that squished out.

While I was working with the weatherstrip adhesive I also glued the 1/16" rubber pads onto the top of the fuel tank saddles. I found it easiest to first cut the supplied sheet to the required width but leave each piece longer than required by about 1/2" or so. After the rubber strips had been glued in place and the adhesive had cured overnight, it was then a simple mattter to trim them to length using an X-Acto knife.
I was originally planning on painting my instrument pod with Stone Creations (Black Granite) which would give it a dark rough texture. This requires a clear topcoat to protect it and after finding a satin clear that was compatible, I made up several test strips. I wasn't happy with the durability of the result so it was time to switch to epoxy urethane. I wanted a darker colour to try stop some reflection and I already had too much gray in the cabin ... black was okay but boring. So out with another colour plus a low-gloss clear coat.

Definitely a perspective error ... this pod is significantly smaller than than the CHR version
Like many things releated to this project, the priority has slightly shifted. Since I now have access to a relatively clean hangar, I've decided to continue installing various interior items, hang the engine and then perform most of the wiring. The bubble will be installed once the majority of the wiring in the console pod and switch panel is complete. Although the bubble could be installed at this time, it will make it slightly more convenient to access various things when wiring the instrument pod to have unobstructed access.

In preparation for hanging the engine, the firewall must be installed first which will eliminate access from the rear to the controls and other areas. I first finished as much of the controls adjustment as I could and also installed the cargo hook plug and LASAR® wiring harness. Although it would have been easier to install some of the other firewall penetrations at this time, I've deferred these until the engine is in place so as to optimize their location. However, I did add a strip of 1/4" painter's masking tape to indicate where the bottom of the frame tube is and thus avoid drilling penetrations in areas that wouldn't work.

Firewall installed and ready for engine mounting

Hindsight: It actually would have been easier to have routed the wires for the engine sensors at this time just before installing the firewall. To access the firewall penetrations from the front (i.e. firewall in place) requires a long awkward reach while it would be easier to do this from the rear. Either way will work, it's just that one is much easier on the back. As far as location goes, I chose to have these wires exit the cabin in the lower firewall rib just to the right of the hook bracket.
With the firewall in place, the next task was to install the engine. This was pretty straight forward and the only glitch is that my caster system is quite low and wasn't designed for the legs on an auto hoist which I had to use. I had to temporarily remove the oil filter and one mag cap to make the installation around the frame members much easier. New conical bushings are also a bit of a pain as they tend to try grab the bolt as it is being installed and torqued.

At this point, my engine was basically bare. The conversion for dry sump operation had already been performed and all shroud building / fitting had been done. However, the only shroud pieces attached were the bottom two pieces (due to conical bushings), the #3 baffle and the small part of #1 baffle ( I lifted the engine in from the right or opposite side). Pretty well any more of the shroud will interfere with the lifting / installing operation and/or would have just gotten in the way. The alternator, carb and exhaust system had also remained off the engine since they really are not needed before this and it was easier to keep the engine sealed without them. I've also deferred sensor installation till after everything has been aligned since these are just more things that can get snagged or interfere with other tasks.

Note that if one is using anything other than an AN816-4[D] straight fitting (which works fine) for the oil pressure transducer, you should check the clearance to the engine mount before installing the engine. In the case of angled fittings, they must be installed before engine installation unless the builder wants to get some practice in removing and re-installing the bolts and lifting the engine.
With the engine in place, the next task was to try install the transmission and drill / bolt the four pylon struts. I'd tried this twice before and it caused me a lot of grief ... this time was no different. The transmission did not line up perfectly with the mounting holes and I used a couple of old bolts ground to points to act as drift pins. Eventually I still had to slightly open up a couple of the holes. Since this is a bit of an iterative process, I also used temporary bolts as they need to be installed and removed quite a few times. The next issue was with the pylon struts and it appears the major source of problem is that one of the aft struts is 5/16" longer than the other one. In reality, it would have been a lot simpler if it had been 1/4" shorter.

Part of the transmission installation process is to determine if the engine needs any kind of shimming. I chose to do this initial alignment with the fan/clutch drum and the clutch shoes removed. This makes it very obvious whether there is a mis-alignment since the lower nut on the transmission input actually fits just into the snout of the engine's crankshaft and is fully visible. While I was doing this, I also took my clutch drum / fan to the local propellor shop to have a static balance performed on it ... I know it is out of round and assumed that it would have significant balance issues. Hopefully the static balance will be a good starting point until I can perform a dynamic balance. Interestingly, it only required one AN960-10L washer to achieve static balance.

Rear and side view ... the yellow lines are graphically inserted to help show the forward tilt to the engine at this point

I believe there are two main ways that have been used to get the engine and transmission aligned:
1) Just install everything and torque it down till it seems to fit.
2) Align the transmission to the frame using the pylon rods and possibly some shims, then align the engine to the transmission with shims and/or conical bushing compression.
I'm choosing the second alternative since I believe it is the proper way to do things. Although I've been told by CHR that shims are not required and to just torque everything down and adjust the conical bushing bolts, I have a tough time doing this and knowing that there will be a significant pre-load stress on various frame members. I required .125" shims under the transmission right side mounts and .063"-.080" under the rear mount. The engine also required some shimming ... AN970-8 washers (0.109") under two of the mounts were too much and I ended up using .063" shims.

This is one area that I may want to re-vist after the ship is operational. Without the shim under the right mount, the mast would be tilted in that direction which should help to offset any translating tendency (tail rotor drift). It will also interact with the resulting rolling tendency.
Note: The plug in the snout of the engine's crankshaft that is used for a fixed pitch engine is prone to rusting and not sealed from the atmosphere in the Safari installation. In fact, water could actually collect here if the craft is exposed to rain and it would be impossible to spot this without pulling the transmission. I put a heavy coat of Corrosion-X on this area to try ward off any rusting.
I sent an email to CHR about the pylon rod that was too long and inquired whether they might have a different rod that would meet the shorter length that I required. The next morning I got a phone call indicating they had already fabricated a new one for me and were just double checking whether to finish it with the measurements I'd sent or to leave off the ears on the upper end and allow me to custom fit and weld it. Since I have a good TIG welder on the field, I chose the latter and CHR managed to get the parts to the courier by 11:00 AM that day for express delivery. I sincerely appreciate their extremely quick response to this matter and they should be commended for it.
Since I consider this one of the most important steps in the whole build process, I spent a lot of time trying to get the engine, transmission and pylon support rods into perfect alignment before drilling the top holes in the pylon rods and the spider on the mast ... more in the Controls section. In fact, this step drove me crazy and I finally realized that I couldn't get perfection but just the best compromise. After temporarily installing and marking the rods to verify they'd fit and how deeply, I took them off and drilled the holes in the upper rod ends to 3/16" while trying to make sure the holes were square to the tabs. The rods were then re-installed, firmly clamped in place and then each hole was through drilled into the pylon. An AN3 bolt could also be installed at this point to preserve alignment. The holes were then opened up with a 7/32" drill followed by a D drill while coming in halfway from each side for the various drilling operations. The holes were then reamed to 1/4" for their AN4 bolts (I'm actually using AN174 close tolerance bolts ... they're a couple of thousandths larger and a gentle tap in versus slide in). Also note that the lower front bolts on the rods have nil clearance to the firewall ... I can just get a castle nut and a thin washer in there with two regular washers on the head side.

Clamped and ready for drilling ... also note the sheet to collect drill chips and keep them out of the clutch / engine
With the main shaft locked into position, I could finally determine the actual length and finish fabrication of the straight control rods that go from the cyclic bellcranks to the swashplate. Although this is slightly jumping ahead, it was done so the control rods and pylon rods could be painted at the same time. The pitch rod could also be installed and the slot in the top firewall rib opened up to it's final size. The updated rigging instructions call for having the swashplate level laterally and 2-1/2" or more from the pylon to the bottom of the swashplate spider. It also calls for the swashplate to be level in the fore-aft plane, the lower knuckle to be level or slightly angled up and the upper knuckles to be at 18 degrees. This can be a pain to try set the control rod lengths while everything is flopping around so I came up with a simple plan. I used four short equal length posts between the swashplate and spider to hold everything in it's final position while I finished fabricating the rods and adjusted everything. A bit of trial and error produced posts that were 2.76" long. I have a lathe to make these kinds of posts but alternatively, four AN4-25 bolts would have been relatively close and a reasonable starting point.

Rear and side view of spacer posts (yes, there's no safety wire or nuts on pylon bolts ... this is pre-paint)

Update: I've received information from another builder who tried this technique. He initially tried posts that were 2.82" long but could not get the full range of control motion that was required. He then switched to 2.69" posts and obtained the required amount of movement.
With the pylon rods drilled and painted, the transmission could be final bolted into place. The first step was to bolt and safety wire the ring gear support and clutch drum to the crankshaft (N.B. don't forget to install the alternator belt). With the transmission suspended for installation and all tape residue removed from the clutch shoes, the shoes were re-installed and held in place with band clamps (the ones to be used for SCEET tubing). The transmission and the pylon rods were then installed followed by the clutch shields . Everything was double checked and then the various cotter pins were installed (remember to include the engine mount bolts). Finally ... a permanent install of the drivetrain.

Left: Safety wire installed; Right: Clutch shoes installed and band clamps holding them in position

Note that in the Rigging Manual it talks about aligning the individual fan blades so they track at the same height. I'm deferring this until I'm ready to run my engine as this step requires one to rotate their engine and I don't want to do that to a pickled engine.
I'd left my alternator off the engine during construction, except to check the belt clearance on the shroud. The alternator was final installed at this point and I found that it was easier to first install the shroud's baffling above the #1 cylinder as the screws holding the two parts together are difficult to access with the alternator in place.
Note that I've provided the Lycoming torque specifications in the Shop section. These are the torques on the alternator pulley nut where the belt just starts to slip and are a much more reliable way of setting the tension than the classic belt deflection method. Although I thought I had my belt quite tight, I was surprised to find that it was only about 3/4 as tight as the Lycoming method when I double checked it. Since it's awkward to adjust once the shroud and oil cooler are in place, it's best to just get it right the first time.

The baffle above #2 cylinder was also installed and then it was time to install the carb and various engine sensors. The first step was to mount the carb temperature sensor since it is on the back side and it is impossible to remove the plug after the carb is mounted. Upon opening the bag with the CHR-supplied carburetor mounting bolts, I was surprised to find two AN5-11 and two AN5H-10A bolts versus the packing list of four AN5-11 bolts ... obviously as a builder neophyte I hadn't spotted this when I inventoried my kit. The -11 bolts will probably just work with my MA4-5 carb if I use thin washers (not supplied with the kit) but first I have to place yet another order for bolts and washers.

While I was looking at the carb, I decided to trial fit the mixture plate that was included in the kit. Even though my kit was clearly ordered as being for an O-360, the mixture plate (and construction prints) are for a MA4 carb as found on an O-320 ... one more item to be designed / fabricated / tested. I'm not sure how this relates to the required moment arm, especially since the mixture arm on the MA4-5 carb actually rotates downwards as it moves. There is also a difference in the throttle arms on the two carbs and the Safari instructions regarding which hole to use are meaningless. Needless to say, this was a very frustrating build session when all I wanted to do was simply bolt the carb into place ... what a waste of time and effort to try identify and correct more factory oversights.

Note the mixture arm at front of the MA4-5 carburetor
I temporarily remounted my oil cooler so I could get the actual lengths for the hoses. I chose to use braided lines on these and needed to get the correct length and obtain supplies. After measuring for them, the oil cooler was removed and I went on to finish some interior and control items. I chose to run the oil cooler lines between the cylinders and the intake runners as this affords them the most protection and the cleanest install. However, I think one needs to be somewhat conscious of the heat from the cylinders and to also think ahead about where the starter, alternator and MP lines / wires will be routed. They can all fit inside the runners, but it does get fairly crowded, especially if one is also running a ground strap through here.
The cyclic control lock was finished at this point. By making sure that the stick was exactly parallel to the mast, it makes the final adjustment of the control rods much easier. I also had to considerably enlarge the slot in the top firewall rib to allow for the full range of motion for the pitch rod.
The various engine and transmission sensors were installed at this time in preparation for wiring the craft. It might have been a bit easier to first check and plan for these while the engine was still horizontal in the crate but the only one that might be required before installing the engine would be an angled oil pressure fitting.

Note safety wire hole drilled in transmission temperature sensor
I wasted a lot of time trying to get the stock CHR exhaust system to fit. Although it is not required at this point, I was planning on having it ceramic coated and needed to verify that it fit properly before sending it away. Instead of just a fit and verify process, this has turned into a cut, splice, bend, reinforce and weld process that wasted a lot of time and effort due to very poor quality and an unuseable fit of the factory parts. Certainly not the bolt-on fit that I was expecting when I ordered this very expensive item.
With the exhaust "can" in it's final position, I re-assembled the shroud and installed the oil cooler and heat collector duct. That allowed me to see how well (not very) that the SCEET tube connecting the two of them would fit. I also decided to modify the oil cooler duct and #2 baffle to try improve the airflow to #2 and #4 cylinders. Lower retension straps for the heat collector were also fabricated.
I'm sort of jumping around at this point and finishing off a lot of odds and ends. The primary focus is in getting the wiring completed but there are plenty of other small tasks to distract me. One of them is to fabricate some "boots" for where the three control rods exit the firewall ... it's been bothering me to have these three large holes just being left wide open. Until the boots are completed and installed, I can't do the final installation / adjusting of the control rods nor can I do the final install of the shroud front since I need access to the firewall.
The switch panel and solenoid board are now installed and wired together. Because the mixture & cabin heat controls are in the panel and I used adel clamps under the solenoid board, they've also been installed but the back end won't be terminated for a bit. Having the control cables under the floor board makes for a clean installation and this went relatively quickly since it had been pre-planned and the bracket already fabricated. Having the bubble off does tend to help in the process since one can sometimes get a different access to things near the front. Also note that the interior side panels have not been installed at this point and this allows extra access to wiring runs along the side areas such as for the navigation lights.
Basically just continuing along the wiring path but I've been a bit delayed by personal events. With the switch panel and solenoid board installed, I found that it was easiest to first work with their interconects (basically power distribution). Next up was to run ground wires to the various areas under the seats and rearwards, followed by power lines and interconnects. I've deferred mounting the actual instrument panel and most of it's wiring consists of pre-strung power / ground wires, sensor inputs and antenna coax.
I've also added the various firewall penetrations. Rather than the single large grommet supplied in the kit, I've used special pass throughs at each of the four corners and also roughly the center bottom. This allowed me to make the vertical wiring runs within the enclosed cabin and makes for very neat weather resistant penetrations. I've also added the starter and alternator cables ... these are a bit of a pain to work with and worth the time to figure out how to make them as short and straight a run as possible. For now, I've run a ground cable from the frame tab to the alternate case pad for mounting an alternator ... this isn't the cleanest / shortest way but there was no real convenient point on the case. It does make it somewhat crowded with the oil lines and starter / alternator / ground wires, but it can be done if everything is well supported.
I continued doing some wiring cleanup and finalized the routing for all the wires inside the cab. I've been delaying the marriage between the instrument panel and the craft ... it's much easier to work on the panel while it's still on the bench. However, I also realized that I'm putzing over this and not moving ahead very fast. I finally took the panel out to the hangar as I knew I had one potential interference and it's much easier to have the panel beside the pod in order to check measurements. That was resolved by moving one wire bundle ... what a pain and just proves it's best to double check things first. I cut a couple of pieces of foam with a U-shaped slot in them so the panel could first be roughly positioned as I threaded the wires through the conduit I fabricated for the bottom of the pod. Once this was completed, the panel was rotated to ~45° which still allows access but shortens the wire requirements and prevents the service loop from becoming too awkward. Now it's time to terminate all the interconnects.

The wire looks like a bunch of spaghetti, but they're all marked so it's just a matter of connecting one wire at a time.
I chose to pre-wire most of the instrument panel which left the other end of the wires to be terminated at various locations around the craft. However, there were a few wires that I'd pre-wired to the switch panel which then needed to be routed and connected to the instrument panel. Due to space constraints, these wires were extremely time consuming and difficult to route / terminate, but at least that step has now been completed. The lesson learned for this type of radio stack and pod installation was that it would be much easier to have fully pre-wired the instrument panel before installing it. Of course, these wires would have been much easier to route if I'd used a round radio / transponder or had left more room under the radio stack.
Most of the non-sensor wires (i.e. power, ground and control) have been routed through the switch panel area to their final destinations and a lot of them are now terminated. This was time consuming to try do a neat job of keeping the wires parallel but it does reduce the bundle size considerably. The sensor wires should be relatively quick to route as the runs have been established and the firewall pass-throughs are in place. I made a mistake of straining my back muscles while working in the awkward pod area and then aggrevating it as I continued doing more wiring ... this has really slowed things down for me and it's time to take a bit of a break from wiring while I let the muscles recover.
Most of the sensor wires have now been run through the switch console area. That leaves the coax and pitot / static / MP lines to be finalized and then this area can be buttoned up. The real time consuming part of the wiring is just about complete.
All of the wiring has been run to it's various locations (excluding coax and boom) and I continued to clean up some of the wire routing and terminating some of the sensor wires ... will the wiring ever end? One of the things I noted when wiring the rotor tach generator is that it would have been more direct to run the wires to it from below, but this would likely have caused the wires to rub on the upper transmission casting. I actually looped the wire up to a pylon support rod and then back down.

The loop at the top is a bit bigger than required since I also have a different sender (with different connectors) that I want to test. Also note the sheet over the fan opening ... works great to catch small dropped pieces and to keep "junk" out of the shroud.

I also realized that it would have been a shorter and more direct run if I'd put my bulkhead pass through for the oil pressure transducer in the firewall side rib instead of the bottom one. Oh well, it's now wired and no big deal.

I also detected a potential wiring problem with my LASAR® system as I have the version with a CHT probe in the hottest cylinder which becomes another factor in determining the advance. To accomodate this plus the CHT gauge, I have a dual CHT probe i.e. one physical probe but with two sets of wires. The problem is that the Westach probes supplied with the CHR kit are 4' in length while the Unison M5340-03 probe is only 3'. No big problem *unless* the cylinder I pre-selected as hottest (#4) turns out not to really be the hottest and I have to switch the probes around. To accomodate this, I've left extra length on all the CHT extension wires so that hopefully they can reach the Unison probe regardless of which cylinder it is installed in.
I kept the non-electric instruments out of the panel while I was doing all the wiring in order to avoid bumping them and to create better access to the wiring. These instruments have now been installed and the pitot, static, and manifold lines have all been run from the instruments to their respective terminations. There is a choice of using either Tygon tube with push on barbed fittings or Nyla-flow/seal tube and fittings. I chose to do all my panel routing with Tygon tubing as it made it much easier to route the tubing out of the pod and down to the switch panel area. The panel is now ready for electrical checks. For now, I've installed my modified analog tach (similar to the CHR digital tach) but I've since recalibrated an R22 tach that I'll be testing at some time in the future ... it's a simple swapout due to the use of electrical connectors and pre-wiring.

In preparation for installing the bubble, I've also been doing a few of the miscellaneous details that I'd deferred, such as the control cables exits from the cabin area. Besides some of the console electrical testing, I want to get my control rod boots installed before installing the bubble. Although it's relatively easy to do this afterwards, it will be much easier to install the top one without obstacles.
I've been a little side-tracked of late as I got involved with a TSB investigation into a fixed-wing fatality. Certainly this is a sobering experience and makes one rethink every aspect of what they are doing. More importantly, it reinforces that every nut, bolt, joint and wire is important ... any shortcuts are just inviting major problems. Although a particular item may not be critical by itself, it may cause the first event in a sequence that leads up to a much larger problem.

As far as actual work on my craft goes, I've been finishing up various minor things that need to be done at some point along the way. Seems I forgot to run the wires for my map light (dumb!) and this took a lot of extra time to do it properly after the basic wire bundle had been routed, laced and was already in place. Other tasks included things like the headset jacks, the ANR power supply, the primer line routing and making sure that all the wiring is well protected against abrasion.

One of the things I'd been waffling on was how to secure the spark plug leads on the boom side of the engine. I've seen pictures of several ships that used the typical fixed-wing technique of attaching the leads to the shroud but I really don't like the look of that and it makes one more thing to disassemble if you're taking the shroud sides off. I finally decided to go with clamps on the intake runners the same way as is used on the O360-J2A in an R22. I ordered LW18959-175-25 clamps from Progressive Air ... interesting that a Canadian distributor was cheaper than the US online outlets. As an alternative, ECI part # AEL71910 is a cross-reference to these.
The bubble has now been mounted and is in it's final position. Removing a bit of the protective covering where it contacts the various parts was not a problem but it was certainly a lot more difficult to remove the covering along the narrow edge. With the "rubber" molding in place it was more difficult to accurately position the bubble, but eventually it was moved into the proper position.
N.B. Installing the bubble clips was quite simple for me but part of that can be attributed to my use of non-standard kick panels as described in the Cabin section. Because of that change, my kick panels were installed after the bubble was mounted which allowed for easy access to all of the front bubble clips. Without this change, access would be very difficult and other builders might want to consider a different assembly order than I used.

The engine shroud has now had it's final tightening of all the various screws that hold it together. This was also the perfect time to double check that various wires and lines had been tightened and properly clamped in place.

In parallel with the other finishing tasks, I had already done the final paint and cleanup on the tail boom. Once the painting was complete I added tubeseal to it using a funnel and a short piece of tubing. The fact that it would only run slowly into the boom and then an air bubble had to escape through the oil in the funnel was a good indicator that the boom is already sealed.

The boom has been installed in order to do the initial setting of the pillow block shims and to trim the tail rotor driveshaft to length. The shaft will then need to be welded shut and painted. I'm not sure if I'll permanently attach the boom or remove it again ... I need to talk to my hangar mates about space requirements.
Wouldn't you know it ... just as everything is rapidly coming together, mother nature strikes. I'm still trying to isolate the cause, but I'm pretty sure that when I installed the bubble and did some general cleanup that some of the accumulated dust contained fiberglass particles. As I was doing this work without gloves, my hands have developed a severe itchy rash that looks like a whole lot of mosquito bites. Normally I'm extremely tolerant of fiberglass shards and have no known allergies, but the result is that all work has slowed to a snail's pace again as it is very painful to grip anything, apply pressure or even close my fingers for that matter ... hopefully this will cure up in a reasonable time frame and the long term result will only be a valuable lesson.
Update: Lesson learned the hard way to be very careful around fiberglass sanding residue ... two weeks and my hands are useable again but there are still some scabs that are healing.
The tail rotor driveshaft has been cut to length, welded and drilled. It's now awaiting better weather so I can apply a thin coat of paint to it.

I've been fighting with the carburetor installation. This was one of those things that I'd assumed was a simple bolt-on and had delayed it's installation so as to avoid getting dust on/in it. After resolving several mounting issues as described in the Engine section, I'm still wrestling with the SCEET tube routing.

Bad flash shadow on the oil pickup fitting but one can just see the edge of the blue fitting. The tape is holding a piece of plastic in place to temporarily seal the intake.
A new offset flange has been built for the carb air. I've also solved some miscellaneous issues such as how to mount a rear hanger for the exhaust. Construction on the doors has also been started. While there is no rush for these during the summer, the jig is now available and I can work on them whenever I have a free hour or two. Since there will be room in the hangar for quite some time, I did the final bolting of the boom to the main frame.
Besides some painting, I've been doing various small tasks such as mounting the carburetor (for the final time I hope), routing wires on the tail boom and running some of the oil lines. I have the original style oil tank and one of the things I found was that the crankcase vent hose was resting on the frame just above the tank. Since this is the type of thing that I'm trying to resolve before it leads to later problems, a couple of adel clamps solved the issue.
The tail rotor driveshaft has been painted and installed along with the pillow blocks and couplers ... more details in the Controls section. This was a more time consuming process than I'd thought but mostly due to the delays with painting and the finnicky nature of trying to get parts to just fit followed by their precise alignment. The tail rotor was found to have a very stiff pitch control and I spent the time to remove the rod ends and loosen them ... the factory had chosen to just install them as-is even though they couldn't be moved by finger pressure alone.
The exhaust system has had gussets added to the tailpipe and I think I'm finally content that it's ready for final installation. The only question is whether I send it out for ceramic coating. The seats are now with the upholsterer and hopefully they'll be finished in the near future.
The routing of the oil lines has been finalized and the hoses installed. I ended up changing the oil tank fitting for the right valve cover drains (i.e. cylinder #4) to a 45° fitting as this allowed the line to run more horizontal rather than have a dip in it that would trap returned oil. The routing of the oil lines, fuel line, starter cable and SCEET tubing is a bit of a Catch-22 ... it seems that the best routing for one of these tends to make it a bit more difficult for the next item. I'm not sure what the best sequence would be but I did mine in the order of: electrical, oil cooler, oil tank, fuel then SCEET. As each line is being run one has to try envision whether it will interfere with items that still haven't been installed. Since the SCEET tubing is by far the bulkiest, one has to be very consious at all times of where it will go.
I finished off a few miscellaneous things like wiring the tail light and the chip detector (disconnected for break-in). One of the concerns I had was making sure that the tail boom was properly grounded to the main frame since the boom supplies the ground circuit for the tail lamp and chip detector plus acts as a ground plane for the antenna. While the boom attachment bolts might supply a suitable electrical connection, I chose to add a separate bonding wire to guarantee continuity. The tail rotor gearbox did not have a good ground path through the paint and required either a bonding strap or paint removal and a star washer which I chose to do. The main rotor gearbox's chip detector appears okay since there are a lot more attach points ... seven mounting bolts plus four pylon bolts.
I did the initial fitting of the tail rotor push/pull cable and then changed the location of the firewall penetration to get a bit more slack in the cable to allow it to better follow the boom contour. Both the front and rear frame tabs that hold the cable ends needed to be bent to allow for cable alignment. The Rigging Manual instructions did not work for my setup as the tail rotor control arm moves considerably more than the cable (2-5/8" versus 2-1/8") ... I'm still working with the factory to identify a solution but so far they haven't provided a consistent and reliable way to rig these blades. The front end of the cable required a cable extension as I could not get the rod end to reach the pedals based on the location where the factory welded on the attach bracket.
The slot for the pitch rod (center control rod to the swashplate) has been considerably enlarged and an extra bubble clip fabricated. I can now get the full range of movement required without any binding. However, the seal that I fabricated will no longer work and I need to fabricate a new one.
The seats have been received back from the upholsterer. I was waiting to cut the slots in the seat support sheeting for the seat belt passage until the final seats were received ... I can now go ahead with that. I'd also delayed trimming the cyclics and fitting the grips until the seats were available ... another task that I can now tackle. Since the upholstery shop is on the field, they will also be making up the various cyclic and collective boots plus some floor carpeting. I've left this with them as very low priority items when they need a small task to fill in some time.
Although my hangar mates have a lot of adel clamps, the one size they were missing was WDG5 which I needed for the tail rotor push/pull cable. These were ordered and finally arrived ... the push/pull cable is now clamped in place. Since I was working on the boom, I decided to install the strobe wiring and head ... with that done, the boom is now complete with the exception of the final tail rotor blade rigging and bolting the horizontal stabilizer in place. The stabilizer is being left off for now to avoid hangar rash. The other thing I need to do is find a clear adhesive similar to RTV to add some extra support to the vertical stablilizer.
I've attempted to re-rig the main controls again but I'm still not happy with the result and haven't locked the various adjustments in place. Although this sounds easy in the manuals, it's much more difficult when you can't achieve the results that are quoted. I've also started to prepare my main blades ... this is also a bit annoying and taking extra time as my older style swept tip blades are unequal lengths.
I decided it was time to finally cut the slots in the seat support sheeting that allow the seat belts to come through. In hindsight, it's a bit of a Catch-22 ... it would have been easier to cut these slots during initial fabrication and before paint, but until the actual seats are available the exact position isn't known. Regardless, it's now done and the seat support sheeting has been installed for the final time (hopefully).
The holes for the blade tip weight modification have been made ... hopefully I'll be able to install the epoxy/shot and finish this modification in the next few days.
The blade tip weights have been added and a stripe painted on the blades. Although I'm not ready to mount the blades immediately, the painting of the stripe was the reason behind doing this slightly out of order. Since I'm using an epoxy urethane paint (i.e. a noxious hazmat) that I didn't want to spray inside the hangar. There was a nice weather break (unseasonably warm ... actually a record high for that day) and I wanted to get this done outdoors before the snow starts to fly ... mission accomplished.
With the seat support sheeting in place, all the seat belts have now been installed. The carb heat control and primer pump with internal lines have also been installed.
I'd been delaying the final adjustment of the control rods and a bit of the interior work until I had a suitable exit boot for the pitch control rod. With this boot in place, the headboard has now been installed and final rigging of the control rods has been done as they should not need to be removed again.
The fuel tank installation had been delayed until after the control rods had been rigged as it's MUCH easier to access the swashplate without having to reach up and over the tanks. With the control rods set, I then installed the tanks ... it sure makes it look different. As noted in the Engine section, I first had to TRY get as much of the chips and swarf out of the tanks as possible. Once the tanks were mounted using T-bolt straps, I then fabricated the inter-tank bracing. I'm well aware of the controversy of rigid versus semi-rigid mounting and I chose to make it as rigid as possible using an X brace. I must be getting sick of painting (plus the cold weather) as I decided to make the braces out of 1/2" stainless tube.
The exhaust system has now been installed. There are a lot of small items such as the mixture control cable that I was delaying in order to make sure there was no interference with the exhaust or even too close a proximity. These can now go ahead. In hindsight, I wish I'd just built a custom tuned exhaust right from the beginning. I wasted a LOT of time, money and frustration correcting the alignment of the CHR exhaust and preparing it for installation. I now believe this effort would have been much better served by just making a performance enhancing system right from the start.
With the exhaust in place, I finalized the control cable runs, oil tank vent line, cabin heat duct, carb fuel line and plug wire routing. It seems like there is no perfect routing for all these items and each placement interacts with the others. I also used a fair number of adel clamps to hold everything in place and prevent movement and possible chafing due to vibration. I tried to keep the fuel line from gascolator to carb as clear as possible ... although this worked out fine, I ended up adding one adel clamp in the center due to it's length. One thing I would recommend is to not do the final cut and installation of the control cable ends until all routing of these items is finalized. I know that I moved one cable in this iterative process and it resulted in a slightly longer (perhaps 2") run but negated an interference issue that I had.

SCEET tube for cabin heat not installed these pictures

A bit of electrical termination still required i.e. landing light
With all the various lines on the left lower side having been routed, I added the cabin heat selector valve and it's SCEET tubing. The valve basically hangs from the exhaust (about 3/16" below) using a short piece of SCEET tube but I did add a couple of stainless tangs at the top of the selector which go inside the exhaust can. Between the tangs and the SCEET tube, there is very little movement of the selector valve.
I'd been delaying the installation of the cyclic sticks and grips until after the seats were installed as these needed to be adjusted for height and rotation using the final configuration. The sticks were trimmed and tested then painted. After that, the grips and associated wiring were installed ... I've terminated the wiring in plugs so I can easily remove the sticks.
I needed to finish a bit of engine wiring that was much easier to do from underneath the craft plus I also needed to take some pictures of the craft for the CofR application. Soooo ... I finally took it off the casters and put it up on it's skids. I even got to try out the ground handling wheels (not impressed with the tires) as I had to move the craft around for the pictures. What a world of difference when working on it now. Although it's now possible to work underneath the craft and it's much easier to work on certain interior areas, it's also much harder to work on the boom and mast areas due to their increased height. If a builder decides to use the low casters like I did, then my recommendation would be to leave them on for as long as possible.
With the extra room under the craft, I could now add the pitot tube and the belly mounted VHF antenna. Now that all of the sensors are finally connected, it's time to perforn final checks on all the electrical wiring. This is done by closing the breakers one at a time and then testing the attached devices. The only one that really can't be tested until engine startup is the alternator charging. Due to it's potential of affecting a lot of other devices, it will be tested at a later time with as many breakers pulled as possible. First round of snags indicated a questionable oil pressure gauge (or sensor), a questionable CHT probe and a partial fault in my tach backup power monitor.
The tach backup power monitor simply required another diode but it was a real bear to install due to it's location. The avionics (transponder, radio and GPS/COM) have been installed and had initial testing. Without a tester, the transponder can't really be tested in the hangar but it does show the correct pressure altitude indicating that the encoder is also working. The intercom and radios are much easier to test, especially since I also have a handheld radio. The GPS function won't be able to be tested until the craft is outside the hangar ... hard to see satellites through a metal roof. The one thing this testing did identify is that the microphone on my passenger headset has an issue that will require servicing ... it only shows up with another headset plugged into an intercom system. I guess that's what I get for buying it as reconditioned. In hindsight I realize that I'd hooked it into my handheld radio to verify it's operation but only checked the headphone part without thoroughly testing the mic ... lesson learned. It looks like I either did a major wiring error on the Westach quad gauge with oil pressure or the gauge is faulty ... with only shunt power (amp meter) and the breaker pulled there is still power to the rest of the meter and the sensor. Next step is to pull the panel and investigate the wiring and possibly remove the gauge for servicing.
The dust boots have been installed on the cyclics and collectives and this meant that the bolts in the cyclic could have their final tightening. I'm really not impressed with the design of the cyclic fore-aft pivot ... this hole was drilled oversize at the factory which introduces slop into the stick. If one tries to tighten the pivot bolt to reduce this effect then it introduces friction into the stick. Not a good design and one of the long-term modifications will be to change this pivot to some kind of bearings. The dust boot on the pilot's collective presented a problem in that I'd welded a tab in place for the collective friction and hadn't left a lot of room for a dust boot. This meant that the boot had to be extremely short (less than 3"). While it works (barely), I'm thinking that I'm also going to have to move the collective friction attach point forward to gain more clearance.
The headset and gauge have been sent to their respective manufacturers for servicing ... hopefully there will be reasonable turnaround on them. The carpets have been completed and installed along with a few other small details like mounting the fire extinguisher. A few other items like the custom light dimmer box have been fabricated.
An awful lot of small details have been completed. The gauge has been received back from Westach (repaired as warranty even though long since expired) and the panel was re-assembled. The throttle grips have been assembled as has the control box on the pilot's side. The ELT antenna was mounted as was the transmission filler / vent. The main blades have had their initial mounting but will be pulled in order to complete some work on them. The fuel level senders were calibrated as was the oil tank which was filled and calibrated. The empty CofG was located and the craft weighed. Other small things were attended to in order to get the final inspection performed.
The final inspection was performed (snag fee) and I received a Flight Authority. The main blades were trimmed to similar shapes, had trim tabs added, were statically balanced and were finally mounted. The tail rotor had it's throw increased to the maximum that we could get and was then dynamically balanced, followed by a dynamic balance of the main blades. Finally it was time for first hover! It's alive!!! At this time I guess it's no longer final assembly (other than doors) but has moved into the arena of maintenance.
The doors have been fabricated and installed but the vents have not been installed in this picture. Basically that's it for major fabrication. I still need to paint my seat bins and I'm going to add an exhaust deflector but those are minor items that fall more into the maintenance arena.
The craft has now been both trailered and flown with the doors on. I need to do some more work on cooling and also the track & balance but those are rigging and maintenance issues.

MISCELLANEOUS

During construction I had been very careful that all the various holes were drilled to exactly the right size; 8-32 screws were a #19 drill, AN3 bolts were 3/16", AN4 bolts were 1/4" drill, etc. For large pieces that are installed with floating nutplates, I made sure that at least one of the nutplates had a precise screw hole such that it would preserve the alignment while the other floating nutplate holes were of the larger variety that allow for some movement of the parts. This philosophy worked well on all the various aluminum panels but it does cause a potential problem on some of the thicker steel parts ... if anything more than the thinnest coat of primer enters the hole, then it needs to be re-drilled after painting for proper screw/bolt clearance. This drilling process can then remove the protective primer and paint and create a place for corrosion to start. While this close tolerance is acceptable for critical holes that align the running gear (especially if Corrosion-X or something similar is used), it can easily be prevented in non-critical areas by just using a slightly large drill before painting. Also note that the more pieces I assemble, the more I feel that critical holes should be under-drilled and then reamed to size.

I worked with an AME (Canadian A&P) who always dipped all bolts and nuts in Corrosion-X before installation. His reasoning was that any slight scraping of the cadmium coating is a potential point of corrosion and this would help prevent it. I'm also putting a bit of Corrosion-X on each of the floating nutplates and also into any of the holes that had to be re-drilled after painting.

I have found one aspect of standard AN bolts that I really don't like; it would appear that their length specifications are designed for a tension installation of thicker material and not a shear application. Specifically, there are many places where I feel that a bolt one size shorter could be used which can be done with two thin washers or one regular (thick) washer, rather than three thick washers, and still provide the proper threads for a cotter-pinned castle nut. However, if one carefully looks at this they can see that the threaded side of the bolt actually has the taper and/or threads within the material's hole and this allows some extra play, even on 1/8" material. Several dozen bolts that are 1/8" longer than required and each having two extra washers does add up in weight and extra parts. However, with the compromised fit one has to go with the longer bolt.

The AN960 washers we use are actually stamped from a piece of sheet metal and have one side with rounded edges and one with square edges and a rougher surface. I'd always thought that if I put the rounded side towards the work piece then I'd prevent scoring the surface or cutting through any coating. I recently read an article that made me realize that while the above may be true, that orientation is backwards of what it really should be. If the squared edge is towards the work piece then the rounded edge is towards the nut and it will allow the nut to rotate smoothly and result in a more consistent and reliable torque setting.

The primary fastener nuts supplied in the Safari kit are AN310 castle nuts and AN365 elastic stop nuts. Most locations should be able to use the slightly lighter AN320 shear nuts instead of AN310's if the builder so desired. I've used MS21042 all metal stop nuts in many places ... they're very light and convenient for places like adel clamps. These nuts are extremely effective and it should be noted that they are the predominant nuts used by Robinson. Also, these nuts can be used in higher temperature areas around the engine whereas it is accepted aircraft practice to not use elastic stop nuts forward of the firewall or in any area subjected to heat.

After going through all the trouble of trying to get a good paint job, I find it ironic that many people then just tighten screws against the new paint thus gouging the paint and going down to bare metal. The simple solution is to use a thin nylon or fiber washer under the screw head. These are available quite cheaply at most of the large electronics distributors and I've noticed that Aircraft Spruce also carries them as part # 04-00217. I've also found that the nylon washers seem to add a bit to the gripping power of the screw ... I assume this is due to compression of the nylon.

One builder was having trouble getting the protective coating off the bubble. Although part of it came off quite cleanly, there was a large amount that only seemed to come off when using his finger nail and wouldn't "peel". After deferring this, the next time he tried removing it, it peeled quite easily. The difference was ambient temperature ... in the 90's for the first try and in the 70's during the second try. I had no problems removing it in mid 70's temperature even though it had been in place for many years.

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Last updated: September 18, 2009