Finally finished up SB #0014 which was to replace a number of rivets in the main spar with stainless steel rivets. Since I have the wings on I decided that it would be a good time to do the rivets along the bottom of the fuselage. Having the wings on will keep the space that needed for teh wing spar to fit into the fuselage spar. I was kind of dreading this, but it turned out to go very well. My only casualty at this point is I can’t locate 2 of the rivet tails from the rivets that were removed. I’ll keep looking and maybe when the wings come off I’ll find them in the spar channel.
First step was to drill out the 62 4mm rivets that run on the bottom of the fuselage.
All the rivets removed along the spar. My technique for removing the rivets is to drill the head using the same size bit as the rivet, in this case 5/32″ (4mm), I use the slow speed on the drill and stop as soon as the head spins off. Then I use an auto punch to punch out the rest of the rivet. Occasionally you’ll get a rivet that doesn’t want to come out or the mandrel punches out and you’re stuck with the shaft of the rivet still in there. Usually you can get those out by using the auto punch at an angle to press against the remaining part of the rivet. If that doesn’t work you can very carefully drill it out using the same size drill as the rivet.
All the rivets replaced with stainless steel ones and put some filler in them as well. Will have to sand them later. I used some recently expired tank sealant on the rivets to serve as an anticorrosion barrier between them and the aluminum skin.
I already did the rivets on the wing spar when I was building the wings so that should be everything needed for the SB.
Today I got the wings on with the help of a good friend. I wanted to do a test fit of the wings prior to getting them painted and it was good that I did. Even though I checked the cut out for the landing gear it did prove to not be cut back far enough so that needed to be done. I also learned a few things that I’ll need to be aware of when I mount the wings for good so that I don’t damage the paint.
My wings fit pretty tight into the fuselage. I had to rock the wing up and down and push in at the same time to get them in. Also it was a bit of a pain to line up mount holes in the spar. I think next time I’ll remember to use the large awl I have so that I have something that can go in the hole and can be tapped in to line things up a bit quicker. For this go around I just used some A7 bolts I had from the wing jigs. I didn’t want to use the actual bolts since I didn’t want to damage them in any way. I only put in 2 bolts per wing and the bolts did fit pretty tight even though I tested their fit in the fuselage spar and the wing spar prior to fitting the wings.
I think one thing that would have helped is to have something supporting the wing at the root. I did put a saw horse under the wing about mid way to allow us to rest the wing while we messed with other things, but the wing kept wanting to slip downward and the large flange at the bottom of the wing spar bent the bottom skin a little. Not too bad and it gets covered by the wing skin overhang and fairing so not a big deal. But I think for next time I’ll cut down a saw horse to fit right at the wing root to keep that at a good height while pushing and wiggling the wing into slot in the fuselage.
Had to cut this back about 1/4″, just about right the the rib flange. I had measured before and compared mine to another builders measurement and it seemed like my wing skin had already been cut to the correct size, but it definitely interfered with the gear.Fortunately it didn’t cause any damage to the gear itself.
Sorry bad photo, but trying to show that the cut goes almost back to the rib flange.
After much work the wings are on.
Happy that the wings are on so another photo.
So with this done. I’ll now prep the top of the wings for paint. I can also finish up the wiring of the wing connectors, pitot/AOA lines and the fuel lines as well and can also finish the service bulletin work. I’ve been contemplating if I should do an engine start. I’d need to put on the prop and a few other wings, but it would be nice to get that out of the way and not have to put the wings on again prior to moving to the test airport. I just don’t know if by putting on the prop I’m open myself up for possible damage while it gets painted. Hmmm will have to think about this.
The tension tool I purchased from Amazon arrived so I set the tension on the alternator and safety wired the 3 bolts that hold the alternator in place. The tool I purchased for around $30 has 2 gauges on it. One that reads the distance of travel (belt deflection) and another that reads the force applied to reach that distance. It’s kind of a cheap tool and I couldn’t find any better quality one on Amazon or anywhere else. There is one that costs $60, but after reading the reviews it didn’t;t seem like it was worth twice the amount money as the one I purcahsed.
The idea of the tool is pretty cool and it seems to be fairly accurate, but the scales on it are only stickers so over time they will probably scratch or fall off. I was hoping that the more expensive one would have the numbers engraved, but that didn’t seem to be the case. Also I did a quick accuracy test to check the tool in the range I needed to read (between 9-12 pounds). For my test I just used a bathroom scale and push the tool down on it. Then I checked if the reading on the tool was the same as on the scale. It seems pretty accurate so decide it was good enough to set the tension on the belt.
The Rotax maintenance manual (as well as SI-PAC-001) has a diagram that notes the torque values for the 3 bolts that attach and hold the alternator in place as well as specs on checking the correct tension of the belt. The manual shows a deflection distance of 6mm (about 1/4″) with a force of 50 newtons which all makes sense. Where the manual doesn’t make sense is next to the 50N value it shows 37ft lb which seems to imply a torque value, but it’s newtons not newton meters and I would think you would measure the tension based on the force of pushing down or pulling up on the belt to the distance specified. With that thinking I converted the newtons value to 11.24 pounds so that’s what I used as my target value to get on the tensioning tool.
Here’s the tension tool I used. On the left is the distance guage, you use the rubber O ring to mark the distance you want to use as the belt deflection. The small tube on the right moves inside the larger tube and that has the force gauge on it. There’s a rubber stopper on the end you push on (right side). Before you use the tool you zero out the O ring on the force scale to zero which is all the way to the left (as shown in the photo). The photo shows the tool ready to be used. The right O ring (deflection) is set to about 1/4″ (6mm) and the left side O ring (force) is set to zero.
Next you place a straight edge along the top of the belt. This will serve as the reference point that the distance gauge will match up to when you push down on the belt.
Position the tool mid way between the pulleys.
Then you just push down on the rubber stopper until the deflection is where you want it. Then you just ready the value where the O ring is on the small tube and that’s the amount of force it took to deflect the belt. I set the tension to between 10 and 11 pounds. I figured a little under tension is better than over which could cause the bearings in the alternator to wear more quickly. I also checked the tension with the twist method which is when you twist the belt it should twist a bit less than 90 degrees.
Once the tension was set I torqued the 3 bolts (2 on the front, one on the back) to the values specified in the maintenance manual and then safety wired to bolts, though I’m feeling like I may be redoing these once I see how it’s done on the TAF planes. I think how I have it should work fine, but maybe there’s a better (cleaner) way to do it). Anyways more safety wiring practice I guess.
Today I started to wiring up the 4 annunciator lights (TCU Caution, TCU Boost, External Alternator Charge, and Internal Alternator Charge) and the 2 switches for PFD reversionary and turbo servo isolation. There’s actually quite a few wires and I want to make it easy to remove the panel so I ended up putting in 2 10 pin connectors so that they can be unplugged easily because they’re not so easy to remove from the panel itself.
In looking at where to put the connectors I decided to create a bracket that the connectors could mount into. The connectors that I had already purchased which are TE mini Mate-N-Lok connectors are panel mount so that was good. I’ve used the circular water resistant mini Mate-N-Lok connectors of the wing and tail so I wanted to keep with the same so I don’t have to buy yet another crimper. The TE crimp die is around $200 so it’s not cheap and it only crimps 20-16awg wires (or 2 20awg into one connector). There is another die that crimps 22-18, and also can do 2 22awg wires into one connector and yet another die that does 22-26. Each of course costs $200. So am trying to stay with using only 20 or 18awg wire anywhere these connectors are needed.
Here’s the bracket I made with the connectors installed. The connectors don’t fit super tight into the bracket so I may try to put some heat shrink over the tabs that come through that hold the connector in the bracket to try to get them to stay a bit better. I also have to finish wiring up the bottom connectors. The crimper I bought (yes the $250 crimper with die) broke and I’m seeing if I can get the small metal part (probably a $5 part) from TE and not have to buy a whole new die.
UPDATE 12/31/2020
I received the new locator assembly for the crimper that I ordered from Mouser after getting the part number from TE. The TE support was great. The locator assembly was around $40 so much cheaper then purchasing a whole new die set. Anyways so having this I was able to finish up the connectors for the annunciator lights and switches.
I wired up the connectors for the MFD and PFD. The MFD just used the single 50 pin connector, but the PFD also uses a 9 pin to connect the backup serial cable from the GSU25. The PFD also gets the config module installed which I still need to do. I had an issue with crimping the pins onto the wires for the config module so had to get more connectors. Once I have those I can finish up the work on the PFD 50 pin connector.
MFD connector all wired up. It came out OK. I cut the CAN bus wires a little short so the wire join is in the strain relief. Seems to work OK, but would be better if it was a little longer. The Garmin docs say only 2.5″ of lead from the shielded part of the cable which doesn’t;t leave a lot of room for doing the join of the wires for the daisy chaining.
The PFD 9 pin is done. It only has the backup serial connection from the GSU. I need to get the config module pins on and mount it into the back shell of the 50 pin connector, then I can finish that one up. One thing to note about wiring up the PFD is that you need to install an ID jumper. In my case because I also have a MFD the jumper goes from pin 10 to a signal ground (I used pin 35). So depending on how many screen you have you’ll need to install the jumpers for each screen depending on function. The MFD didn’t need any jumpers. Also the Garmin manual shows a connection from one of the signal grounds to the back shell. This is only for the GDU37X displays since their back shell doesn’t connect to ground. I have the GDU460 so no need for the extra wire.
This is how the config module mounts into the back shell. There a very small connector with 4 28awg (I think) wires connected. Those wires need to get the #20 socket pins put on, but they are different pins than the pins used in the rest of the connector. I messed up the crimps on them so I need to get more pins. I’m seeing if I can get a few from Garmin otherwise I need to buy a whole config module, just to get the pins :-(. Fortunately the G3x config module is only around $50, the GNX one is around $500.
UPDATE 12/27/2020
I received the config module from Aircraft Spruce yesterday so I was able to finish up wiring the PFD connector. I’m still hoping that Garmin responses and I can get a few more of the pins, but at least I was able to proceed and finish it up.
The pins are a bit weird, they have witness holes of both sides of the pin. You have to look for the thicker band that runs around the pin and the end that the wire goes into is on the shorter side of the band or also the opposite end that has the flat section on it.
Nothing too exciting. I got the AC200 propeller control and the manual switch installed into the panel. These are rear mounted so it’s best to get these installed sooner than later. The funny part is that I had purchased the wire loom extension a while back. This is the wire that runs from the slipring by the gear box back to the AC200. I did this so I could finish up the wiring that ran through the firewall and be done with it. Well I had a 50/50 chance on getting the orientation of the cable right and I messed it up. I put the connector that’s supposed to plug into the AC200 in the engine compartment and the connector that plugs into the slipring behind the instrument panel. So rather that saving me time I now had to remove the wires and rerun them…. Arghhhhh!
The AC200 and manual switch fit perfect into the panel. I guess I got the CAD drawing right 🙂 They even use the same screws (#6-32 UNC) as the other sub panels.
UPDATE 12-27-2020
I finished re-running the cable from the engine bay to the prop control and also wired up the power and ground. The prop control comes with a prewired connector for the power and ground about 3-4ft of red and black tefzel wire. I had already ran wire for this so I just cut back the wire and spliced them onto my existing wires.
I started the install of the propeller system today. First things was to install the slipring assembly into the rear of the gear box. This consists of the actual slipring and the brush assembly. I figured this would be pretty easy but ended up being a bit more time consuming than I had planned. There were 2 issues that kept me having to rework things. One was getting the right amount of wiring out through the center hub. Initial I though I had pulled enough through and started to tighten things down, but found after a quick test fit of the prop extension that it was a bit short. The frustration was that the wire would be pulled back in as you tightened down the AN3 nut on the other end of the rod. There’s a piece of heat shrink that is on the wiring that I wanted to have situated on the plastic cup part of the slip ring mount and it was just a matter of getting that set into the notch of the plastic cup and not letting it get pulled in by the bit of tension that was on the wire (it’s coiled up inside the gear box hole). The other issue was that Airmaster gives you 2 thin spacers to use where the slip ring meets the gear box. They are used so that the bushes line up with the copper rings on the slipring. I did a fairly good test fit of both the slip ring and brush assembly, and determined that one spacer was needed. Well after some tightening that didn’t seem correct and I had to remove the brush assembly and slipring to put in the second spacer.
So while a bit frustrating the install isn’t all that difficult. I’ll install the extension and hub in a few days once I get the jointing compound that Airmaster recommends to use on the threaded inserts.
This is one of the recommended greases for the propeller. This will mainly be used when installing the blades, but a bit of grease is also used on the slipring where is meets the rear of the gear box. You only lightly great this area where the rubber O-ring is. You don’t grease the copper rings, though I suppose it might be good to use some conductive grease in on them… I’ll have to check with Airmaster if there’s anything that should be done to the copper rings.
Slip ring installed (sorry it’s out of focus). So this is the part that spins with the prop and the brushes (not pictured) stays stationary. It’s held in with a long threaded rod that is fed through the hole in the gear box. On the front side there’s a plastic cup that inserts into the hole and the threaded rod which is attached to the cup passes through the center of the slipring. There’s an AN3 (10-32) lock nut and washer that then holds the slip ring to the rear of the gear box. You don’t need to tighten this nut very much, just enough to take any wiggly out of the slipring.
Slip ring with the brush assembly installed.
Here you can see the plastic cup and how the wire exits via a groove in the cup. The black heat shrink sits into that groove and there’s enough wire so that you can make the connection to the hub with the extension on.
And another view of the wires exiting the prop shaft. There will be a 3.75″ extension that the wires need to pass through as well so you need a bit of extra here to make the connection to the hub.
I’ll update this post when I install the extension and hub.
UPDATE 12/31/2020
Finished up installing the prop extension and hub. I had ordered some zinc jointing compound as suggested in the install manual. I used this on the M8 inserts that go into the prop flange on the engine and on the sleeves that are already mount on the extension that connect into the hub. I used just little and made sure not to get any on the area where the bolt/washers contact the inserts or on the prop flange.
I also put a little inside the holes where the inserts mate into after passing through the propeller flange.
Everything connected. Also remembered to connect the 3 wires inside the hub and put on the heat shrink of the connectors. I didn’t take any photos because it was a pain to hold the hub and connect the wires and do the heat shrink as well. Also was careful to make sure the wires didn’t get in between the hub and the extension. All the bolts are finger tight first. The bolts going into the propeller shaft flange are M8 and the ones going into the hub are AN5 and are tightened to 18 ft lbs. I was able to use a ratchet extension through the front of the prop extension since there are large hole in the extension that line up with the M8 bolts. For the hub there was enough space to carefully get the head of the torque wrench in there too get them torqued up. 18 ft lbs. isn’t really all that much so it’s pretty easy too get these tightened. There’s also a pattern to tightened them, kind of like when you put a wheel on a care. You tighten the bolt diagonally across from the one you just tightened making a “V” then do the same with the next 3 bolts. I tried to 9 ft lbs., then 12 ft lbs, then finally 18 ft lbs.
Put some torque seal on the bolt heads.
Airmaster uses Nord-lock lock washers so there’s no need to use any kind of thread locker or safety wire on the bolts. Also the torque values seem a tad bit higher that normal for these size bolts.
Finally picked up my Airmaster propeller from TAF today. I ordered it back in June and was supposed to be here in early October. An inventory of the parts looks good. The only issue is that I ordered a paintable spinner and it came with a chrome spinner. I’m asking TAF how long will it take to get a new spinner. Also I don’t know how that will affect the balancing of the prop. It looks like Airmaster balances them in house so I would think I need to do a rebalance because of the new spinner. Not too big of a deal I guess.
I’m using the standard issue prop that TAF uses for the Sling 4. This is the AP332SCTFH-WWR70W system which is a 70 in diameter 3 blade configuration with a 10.3″ diameter spinner. For the Rotax 914 (and I believe the 912) you can use the mini slipring which mounts on the rear of the gear box and extends through to the propeller via a hole rather than the front, side mount. Also there is a 3.75″ extension that is used between the propeller hub and engine prop flange.
I ordered some AeroShell Grease 22 (recommended in the install manual) to use for packing the slipring and the propeller blade assemblies, though I may not be mounting the blades until after the plane is painted to reduce any chance of them getting damaged. Installation looks to be pretty straight forward. I’m still a bit confused about the procedure for actually mounting the blades, so I might see if Jean can help me with that when the time comes. The blades also have to be installed in the correct position (because the prop is already balanced) so will need to be mindful of that when the time comes.
The whole system comes in 2 boxes. One box has the blades and the other box has the extension, hub/spinner, and a smaller box with all the electronics.
So will need to work on mounting the AC200 and manual control to the panel and the extension, hub, and slipring to the engine.
I wired up the connections for the switches sub panel. Nothing too exciting. The switches use Easton connections, but they are the 187 size, not the typical 250 size so I order a bunch of connectors directly from TE. The TE Site is pretty good. You can order small quantities and it’s free shipping, well at least on everything I’ve ordered so far. So no more paying $10 in shipping for $5 worth of connectors when you just need a few more to finish the job.
The last thing I need to do is to wire up a connector for the dimmer. The dimmer uses 3 wires, well actually 2 wires and the shield (for ground). I’m just going to use a 6 pin mini mate-n-lok that I have already. I’ll be using similar for the annunciator panel connection.
Lots of wires. I’m thinking I’ll cut out that small bit of panel between the top (large) rectangle and the lower (small) rectangle so I won’t need to disconnect the wiring from the main pump circuit breaker to get the switches sub panel out. That will make it much easier to get to it in the future.
UPDATE 12/23/2020
Finished dup wiring the start switch h and the switches sub panel. I had to wait for some 187 fasten connectors that I ordered from TE. The shipping is free but it takes a little while to get them directly for TE.
Switches sub panel all wired up. I didn’t push the connectors all the way on because I have to remove the sub panel and they will be really hard to get off once fully seated on the switches.
Finished up the wiring for the start switch. It uses #6 screw terminals so had to get some PIDG crimp on connectors with the #6 lug. Also I have a 12awg ground (probably over kill, but also is ground for the alternator and batt switches on this sub panel) so had to get a few for the larger wire size. I think all the rest of the wiring is 18awg. I just grounded the shielding on the magneto wire to the ground lug on the start switch. The screws seem long enough so should be OK.
After doing some prep work on the fuselage I decided to work on getting the antennas installed so that they will be ready to go after the plane is painted.
I first had to swap out my monopole ADSB antenna with a blade type antenna (RAMI AV-74). Since I’m now using the GNX375 I needed to switch to the blade type antenna to meet the specs called out in the manual. To install it I just had to drill out 2 new 3/16″ holes for the mounting studs to pass through. I’ll also need to step drill the interior holes larger so that I can get the nuts on to the studs and also get a socket in to tighten them. For now I wanted to get the holes drilled in the skins. I used the template that came with the antenna and lined it up to be centered on the bottom of the fuselage and centered over the existing 1/2″ hole that the monopole antenna had used. I ended up having to up size the 3/16″ holes the 13/64″ because I guess I didn’t drill the holes exactly on the template… Ahhhh! Anyways not too bad and the antenna seems to be lined up straight.
Next I installed the rivnuts for the top (COM1) antenna (RAMI AV-10). I had waited to install this until I had the antennas so I could verify the bolt size that was needed. The antenna ships with #8 screws so I used M4 rivnuts and will order some flush mount M4 bolts to install the antennas. The M4 bolts are a little smaller that #8, but its pretty close and I’m trying to keep as much of the screws metric as possible.
Once that was done I need to drill out 4 mount holes and a large center hole for the bottom (COM2) antenna (RAMI AV-17). When I built the fuselage I had installed a backing plate bracket for the antenna, but I didn’t drill out the holes. After some double checking that the holes in the bracket matched the holes in the antenna mount I just needed to drill the holes out through the skin and install the rivnuts. The antenna is a bit offset from center because I didn’t want the cable to interfere with the elevator torque tube that runs through that area, but its on the bottom and I don’t think anyone will notice.
ADSB antenna fits. Still need to do some work on the interior side so the nuts can fit onto the mounting studs.
Got the rivnuts installed for the COM2 antenna. I also checked and there’s no way to hit the antenna on the ground even if you tail strike the plane. I was worried that if I had mounted it back further that that might happen if coming in a bit tail low.
