I started to verify and test the ELT today. First step is to verify the connector is wired correctly and to see if the GNX375 is sending the GPS data to the ELT. Once all that checks out I will remove the ELT from the mount and while monitoring 121.5 MHz I’ll shake the ELT forward and back to trigger the ELT via the G shock switch. After that will be the 406 MHz test which I plan to do using 406Test.com. The site seems to only be for Artex ELTs, but should make the test much easier. I’ve signed up on the site which costs $39.95 for 6 months, but haven’t tried to run the test yet so I’m not totally sure how it works. It looks like you just use the switch on the ELT itself and set it to the “Test” position (down) for 1 second. This will do 2 things, it will show error codes using the LED on the ELT and also send information via the SAR satellites which will be available on the 406Test site.
To test the GPS sending I rigged up the serial connection between my laptop serial port and the 15 pin harness connector for the ELT. I just used some extra Garmin pins and sockets to more easily connect to the connectors. Only 2 connections are needed. Pin 2 on the 9 pin laptop connector goes to pin 9 on the 15 pin, this is the data connection. Then you need to connect pin 5 on the laptop connector to a ground somewhere on the aircraft (I just connected to the seat rail).
I downloaded Putty (a terminal application) to my laptop and set the serial port setting to 8 data bits, 1 stop bit, no parity and turned off any flow control settings. Also the “Aviation format” serial data is sent at 9600 baud from the GNX so set the same in putty. When I connected Putty to COM4 (what my USB to serial adapter shows up as) I was pleased to see lots of text scrolling in the terminal window. I’m happy that worked so I didn’t have to take apart the GNX375 connector again.
Next I’ll do the G switch/121.5 MHZ test and the. 406 MHz test to finish. off the testing of the ELT. I know I’ll have to replace the batteries in 2025 which seems quick, but I’ve had the ELT since 2017 already :-).
I started putting together the empennage today. Things seemed to go along OK. Getting the washers installed between the hinge and the mount was a bit frustrating. I actually used a little super glue on them to get them to temporarily stay as I installed the elevator to the HS. The few that fell off I was able to get them installed after some effort. The most frustrating part was getting the elevator control tube mounted onto the control horn on the elevator. You would think that the holes in the side of the fuselage would line up with the bolt head and nut that attaches the control tube to the control horn, but it doesn’t so you have to work 2 wrenches inside the small area with little room. I got the bolt and all the washers installed as per the manual, but torquing the bolts to a known value seems a bit impossible.
NOTE: The factory says they attach the eyelet to the elevator control horn prior to installing it onto the horizontal stabilizer and then just screw the large torque tube into the eyelet once its on… yeah that would probably have been easier, but it’s a lot of work getting the elevator on so you don’t want to take it off.
Just need to install the rudder and test the trim and strobe lights. Then I need to work on getting the elevator and rudder setup and working.
NOTE: Make sure to torque at least the center hinge bolt in the elevator before you put on the vertical stabilizer. You can do it once the VS is on, but it’s a real pain (as I found out) and you need a 7/16″ torque extension so that you can properly torque the AN4 bolt, but seems like you need this for the other hinge bolts as well anyways.
UPDATE 09/24/2021
After a bit of adjusting I got the elevator rigged up to 19.9 degrees down and 29.8 degrees up.The finishing manual says 20 down and 30 up, but I only have so much movement in the elevator so I can adjust to 20 down, but then it will be a bit less than the 29.8 up that I have now. I think it’s pretty close and also it depends on where you take your measurement from on the elevator so seems like it will work fine. I’m thinking that I may try to file the main elevator stops (under the center console) a little to see if I can open up the swing of the elevator a bit.
I also found out from the factory that it’s OK to file the pitch AP servo stop bracket. I had notice that there was not way to adjust the small control tube that connects to the AP server so that the AP arm doesn’t hit the stop in one direction. I didn’t need to file much. maybe less than 1/16 of an inch on both sides to get it so that the elevator control hits the main stops rather than the AP servo stop.
The other task I completed was getting the pitch trim set up. Th manual says to run the pitch servo all the way up and then adjust the trim tab to be 8 degrees from the surface of the elevator. I used a angle guide that allows me to reset the zero so I simply held the elevator aligned with the horizontal stabilizer and with the trim tab level wit Beth top skin I set the angle guide to zero. With the angel guide now reading zero I adjusted the trim tab to 8 degrees up using the clevis on the trim servo and tightened the bolt against the clevis to hold it in place when everything looked good. I also made sure to install the cotter pin on the pin that connects the trim tab to the clevis.
8 degrees up from the elevator surface seems like very little, but I guess you don’t really need that much nose down trim.
My control sticks aren’t connected yet (need to cut the sticks a little shorter) and I have no other way to control the pitch trim so I was able to use the interface for the VPX to control it. At first I noticed that I had to set it to the “reversed” setting to get it to run in the correct direction. I suppose I could have left it that way, but it was a pretty simple fix to just swap the 2 power pins at the connector in the elevator that connects to the pitch trim servo.
Just a few photos of the plane with the empennage installed. Jean stopped by the hangar and was very encouraging of the project so that got me feeling good. Next is to rig the rudder which doesn’t seem too difficult, but knowing how things go on the plane it will have its challenges.
Today was a big and stressful day. I started the engine on the plane for the first time. After checking the electrical, fuel pumps, and doing the oil purge as per Rotax, I felt that the engine was good to go. I cranked teh engine for maybe 3 seconds and then pulled the choke and cranks it for another few seconds and boom it fired up.
The engine ran pretty smoothly even though the carbs haven’t been synchronized. I ran the engine at 2000 RPM until I saw the oil pressure and temps come up. The oil pressure went up to maybe 68 PSI and then came back down to around 50PSI, temps also looked very good so I ran it up to 2500 RPM for a few minutes. I also revved it up to 3000-4000 RPM for very short bursts just for fun. The engine felt very strong and ran very well. We probably let it run for 2-3 minutes total and I felt that was all I wanted to check this time around. All the sensors and gauges seemed to be reading reasonable values, but will need to double check everything on the next run.
I would have considered it a very good first test run if I didn’t notice some oil dripping from the exhaust after I stopped the engine. There was also a little oil on the inside of the bottom cowling where the exhaust connects to the muffler. I cleaned up those areas, checked the oil level (which looked the same as prior to start), cranked the prop through by hand to check the compression and finally gave the engine a once over to check for anything odd. We did a second run and didn’t see any more oil and the engine seemed to be running even smoother so I figured I’d cut my lose and call it good for now. I also to double check everything to make sure running the engine wasn’t doing any damage.
Here’s a video of the first run You can notice some white smoke coming from the exhaust and there was some splatter on the hangar doors so it seems like it was blowing out some oil. Upon further investigation using an endoscope on each cylinder all looks good. I’m going to do a compression test to make sure the rings are good. My thinking is that it may be some burn off of packing type greases/oils that were put in the engine or might be a bad seal in the turbo.
For thesecond run I removed the top cowling. I had put the to top cowling on just because the lower cowling gets a bit close to the spinner flange without the top cowling installed, but fortunately the engine doesn’t vibrate too much so it doesn’t hit it. In this video you can see the fuel leak from the second carburetor (which I knew about). After watching the video I was able to tighten the fitting which seemed to do the trick. I originally thought the gasket on the bowl was leaking and was going to fix when I did the floats AD. My friend was mainly filming the engine itself on the second run because he was looking for the oil leak which didn’t seem to happen again. We only ran the engine for 1-2 minutes because I really wanted to double check all was good and was concerned that I may be damaging something.
My hack to get fuel into the engine. It’s only a 2 gallon tank, but I was only showing 1.5 gal/hour burn so it technically would run for a while on that. I don’t want to store a lot of fuel in my hangar anyways so I guess this will work for testing.
I also did the tappet check as part of the Rotax oil purge requirements. All the tappet clearances are within spec. The front tappet of cylinder #3 and the rear tappet on cylinder #2 are a tad bit soft (I can push on them and the tappet moves a little), but I never ran the engine up to 3500 RPM for 5 minutes so will do that any check these tappets again. It’s pretty easy to get the valve covers off and on so should be way to check them.
UPDATE 12/18/2021
Following the Rotax video (and 914 Maintenance Manual) I did a differential compression test on all 4 cylinders. The only thing I didn’t follow was to run the engine to get the temperature up since I want to be sure I’m not damaging the engine by running it. I did this check because after my first engine run I noticed some oil dripping from the exhaust. In any case the procedure is pretty straight forward: remove all the top spark plugs, find top dead center on the cylinder you want to check, attach the differential tester to the spark plug hole and increase pressure to 80 PSI, then read the drop on the second gauge of the tester. The pressure drop can’t be any more than 25% of the first gauge, so in this case no more the 60-65 PSI. All my cylinders were only down by 1 or 2 PSI so they all seem fine.
Pretty much what all the cylinders tested as… 1 or 2 PSI down from the source pressure so the rings seem to be fine.
Prior to engine start I want to make sure as much stuff I can check is done so hopefully the engine will just start up. So far I haven’t found any glaring issues. Today I checked that the fuel pumps were wired correctly and that they function as expected. I used a 2 gallon fuel container and stuck the hose ends into that. I set the fuel selector to the right side tank and ran the aux pump. It took a few seconds but the fuel pressure came up so I turned that off and tried teh main. That showed good pressure as well.
The only issue I noticed was some fuel coming out of the overflow tube. Upon some investigation I noticed some fuel leaking from the left side carburetor. When I checked out the cir clip I’m thinking maybe it loosened the fitting that connects the fuel line to the carburetor so I took teh fuel line off and tightened the fitting and reconnected the line. I ran the pumps again and I still see a little leakage come from maybe around the base of the float. I’m wondering maybe the float bolt wasn’t correctly torqued at teh factory or maybe the gasket is dried out. In any case It’s not a big leak and I need to replace the floats anyways so I’ll get a new gasket when I do that.
Fuel pumps seem to work OK. Both pumps show about 3.7-3.8 PSI. For a brief time I saw fuel flow as well, but I think that was just until teh float chambers filled up and then it went to 0 again.
I have a little bit of a fuel leak on the left carburetor, seems to be from the top of the float bowl. Hopefully I can rectify that when I replace the floats.
Hoping that I can do the engine start tomorrow morning.
Prior to engine start I want to make sure I have some braking ability, even though the plane will be tied down I just feel better that I can use the breaks to slow or stop the plane if needed. The process actually worked out pretty well, though the left brake feels a little soft so I my do a bit more purging on that side.The hardest part is getting the connectors on the hand pump to not leak. Also I think maybe the left side nipple has an issue because it seemed to leak way more than the right side as I filled the lines and I only opened it a quarter turn if that.
Once I got the hose on the pump a bit more secure and leak proof I periodically would check the reservoir which I had removed the mounting screw from. Also has to verify the the parking brake was in the off position. The process is pretty simple put the brake fluid in the hand pump, connect the hand pump to the bottom of the brake caliper, loosen the nipple nut and then pump the fluid up into the brake system. The fluid should eventually come out in the reservoir in the the engine compartment.
I’ve never done brakes this way, Ive always used a vacuum pump and sucked the fluid from the master cylinder so I was a bit unfamiliar with this process. It seemed like fluid was pumping in, but I didn’t think it was going to work. However after a few iterations of pumping the fluid and checking the reservoir to my surprise after maybe the 4th or 5th the reservoir was almost full. I used a syringe to remove some fluid from it and moved the the left side to do the same. The left side seemed to be a bit more difficult because the threads on the nipple seemed to leak a bit so a lot of fluid ended up in the rag that I had on the ground to catch drips. It also took quite some time to fill the reservoir the rest of the way up, I must have check it 5 or 6 times and the level was pretty much the same each time, but then all of a sudden the reservoir was full. I removed some fluid to bring it down to about 1/4″ from the top, but noticed that after using the brakes a few time the level is a bit lower so there must be some air in the lines still.
It took a few minutes to figure out which nut to loosen. It’s the small 1/4″ nut on the nipple at the bottom of the brake caliper. The threads on the right side didn’t seem to leak, but the left side did a bit. Of course once they’re tightened they don’t leak just when they are loosened to allow fluid to flow through.
After almost filling the reservoir via the right brake lines I removed almost all of the fluid with a syringe. I move to teh left brake and then filled the reservoir again.
This is what I left the reservoir filled to. The Matco (and TAF) instructions say 1/4″ from the top (I’m a little less that that). I did notice after working the brakes and setting the parking brake that the level has dropped another 1/4-1/2″ so I think maybe there’s still some air in the lines. I did see a few bubbles come out of the reservoir so maybe some will work their way out after it sits a bit. I’ll recheck in a few days and maybe run some more fluid up the lines. The parking brake seems to hold pretty well though.
I finally got the Rotax TLR software working and talking to the TCU so I could do the throttle calibration. The hardest part was just getting the software installed and working with the correct USB to serial adapter. I detailed what I did to get that to work in another post.
Once the software was set up and the laptop could communicate to the TCU it was just a simple matter of running the Throttle Calibration in the TLR software by pressing “T” and following the steps that it gave. After calibration was complete I went into Monitor mode (by pressing “M”) and verified the “Load” values were correct for the different throttle positions. The Rotax video for the throttle calibration shows the deviation that is acceptable for the idle, full and boost throttle positions, but mine were pretty much dead on.
With throttle in idle position the “Load” value was 0% and the servo was at 100% (full closed) which is correct. Also looks like the airbox and ambient pressure and airbox temp sensors are working. It was a hot day today so 100 degrees Fahrenheit (38 degrees Celsius) looks about right.
Did a check at full throttle to the boost detent and looks good at 100% Load.
And lastly set the throttle all the way to full boost and 115% Load looks good.
I did a few run throughs and all the readings were pretty close so looks like the throttle adjustment is good. Now I just need to finish the oil purge and do a check on the fuel pumps and I should be good for an engine start.
UPDATE 09/16/2021
I noticed some grinding when going from full to idle throttle which pulls against the spring o the throttle lever on the carburetor. I thought that maybe the nuts that hold the throttle cable to the throttle lever might be hitting the throttle mount, but it turns out that it was the cable inside the sheathing that was causing the binding. I ended up disconnecting the throttle cable at the engine side (since it’s much harder to deal with the cable on the throttle lever side) and pulled the cable out of the sheathing and then used some lithium grease on the cable. I coated the cable and sprayed a bit into the sheathing. I re-installed the cable and did another throttle calibration. Now the throttle lever moves very smoothly so seems like the problem is resolve.
I also added a cable stop just as a safety measure so if the cable come loose then it should still function and control the engine RPM. I also added some heat shrink to keep the cable from fraying.
These are the cable stops that I order from Aircraft Spruce. These are the same stops that are used on the choke cable that fit into the choke lever on the carburetor.
So I thought it might be good to post something about installing and setting up the software that is available from Rotax for connecting the the 914 TCU. This is particularly for TLR46a 64-bit which probably most people will be using. The software itself is pretty easy to use, but there seems to be some issues when doing the installation. From the Rotax forum posts the people that do have issues look to be either moving to an older 32 bit system or reinstalling their OS to get it to work which didn’t make sense to me. It does seem that many people don’t have any issues, but then again if they don’t have issues then they’re not going to post anything so you don’t really know. I, of course was one of the lucky ones to have issues running the software on my Windows 10 laptop. So since I didn’t find a lot of “accurate” advice in the way of getting the software to work if you do have any issues I thought it might be helpful to someone if I posted what I did to get it to work and what I pieced together from a few places that I found some information.
Step 1: Figure out which software to download
First issue is you need to figure out what version of the TLR software you need to download. Most people doing a new aircraft build will most likely be using versions 4.6 which is for the newer TCU (part #966 741) which is printed in big letters on the front of the TCU case. Once you know the number of your TCU you can head over to the Rotax Owners site and go to the manuals section. Then click the headings “914 Software”. The other chose when using the 4.6 version is do you have a 32 bit system of a 64 bit system? If you’re using a PC or laptop from this century then it’s probably 64 bit. If you’re not sure then you can look at your PC properties and it will say under the “About” section. In windows 10 just open Settings and type “About”. Now you got the correct version of the software and got that downloaded.
Step 2: Get your USB to Serial adapter working
Next step, unless you’re using a desktop PC with a long straight thru serial cable then you’re probably going to use a laptop to connect to your engine TCU. Most laptops don’t have a real serial port so you need to get a USB to serial adapter which are very cheap now. One thing to be aware of though is a USB to serial adapter that uses the “Prolific” chipset will not work. I know first hand and also Rotax had a write-up about that had some details about using a USB to serial adapter with TLR and it mentioned that any adapter using that chipset will not work with the TCU. So when you plug in your adapter and if it has “prolific” in the name under Device Manager (I think you can see the chipset if you get properties on the device) then get yourself another adapter. The only other chipset I know of is FTDI so that’s what I searched on Amazon and got one for about $10. So now you have the correct USB to serial adapter and you just need to get the drivers installed for that. I just did a search on Google for FT232R and I downloaded the executable version of the VCP drivers for Windows. I tried installing the drivers through device manager and the USB Serial device still wasn’t working (yellow exclamation on the device name), but the executable version installed fine and the USB adapter looked good in teh Device Manager after the install. Now that you have a working COM port note the COM port number in device manager, mine was COM4 (as shown in the photo below) and you don’t need to change it like the TLR installation instructions say. That is only if you are using the 32 bit version of TLR.
Step 3: Install the TLR software
Now do the install of the TLR software which will put the software in C:\TLR64 and also install a program called DOS Box under the C:\Programs Files (x86) directory. This is where it gets a bit confusing and what seemed to break for me. The TLR program itself is 32 bit. If you try to run the executable on a 64 bit system it will just say the program won’t run on your system. Since Rotax is lazy and didn’t recompile TLR to run on 64 bit systems they used DOS Box as an emulator. TLR runs under DOS Box which is important to remember when you set up the COM port in TLR. The first time you run TLR it will pop up a selection box that you use to set the COM port mapping in DOS box. Then TLR starts and you select the video mode, and then the COM port to use, but the COM port you select in TLR doesn’t correspond to what the USB serial adapter is reporting in the Device Manager, it’s the COM port in DOS Box which then maps to an actual serial port on your PC.
What I found is that selection box that pops up when you first run the TLR software breaks DOS Box so when I ran TLR again it would just show “Error 68” in the DOS window. I’m sure you may get lucky and it will work, but it didn’t for me so this is what I did to get to get it working. After I ran the installer I when to the C:\Programs Files (x86)\DosBox_MB6 directory and double clicked the “dosbox” executable and then just quit it.
This creates a config file in your user directory under AppData\Local\Dosbox. You may need to select properties on you folder and enable “Show hidden files and folders”. Edit this config file.
You need to add in the DOSBox serial to PC COM port mapping and some auto execute lines so that it automatically launches TLR when you run DOS Box.
Find the “serial1=” and add in the mapping, your “real port” will be whatever shows for your USB adapter in device manager. Mine was COM4. Also remember that serial1 in DOSBox is COM1 in TLR so when you configure TLR use COM1. Are you confused yet?
There are a few lines that you need to add at the end of the file under the “autoexec” section of the config file as well. I copied these from the DOSBox config in the C:\TLR46 directory. And that show be all you need to change in your Dos Box config file.
Step 4: Setup TLR
With DOSBox configured you should now be able to run the TLR software (which runs DOS Box, which runs the TLR software) from the link on your Desktop. The first run will ask you to select a display mode (I selected “V” for VGA) and then the COM port to use. If you mapped your USB serial adapter to “serial1” in the DOSBox config file then select “1” for COM1. TLR should open and let you select options like the throttle calibration or monitor options. If it crashes with “Error 68” then something happened in the serial mapping or the DOSBox config got messed up. You can always run the dosbox executable again just to see if that runs OK, it will also report that it loaded the COM port so you can verify it’s starting up OK. Obviously you will get a Serial I/O error reported in TLR if you’re not connected to your TCU and the master switch isn’t turned on. To connect your USB serial adapter to the TCU you should be able to just connect the serial port on the adapter directly to the serial port of the TCU or you can also use a straight through serial cable if you need to extend it.
Well hope this helps if you had issues with the TLR software install.
Well today I had hoped I could do the throttle calibration seeing I finally got the Rotax TLR software working under Windows 10. But seems that the TCU doesn’t like the USB to Serial converter that I’m using so I need to order one with a different chipset. I’ll write up the details once I get it working… hopefully tomorrow if I can get the new dongle delivered.
In any case I decided to look at verifying the adjustment of the waste gate. I had to remove the cable when I installed the servo motor for the waste gate because I mounted it on the inside of the cabin rather then in the lower pilot side of the firewall on the engine side. I really just thought I would be verifying that it seems to work OK and adjusted to open and close the waste gate to it’s full positions. After some investigation though I noticed the movement of the waste gate seemed like it wasn’t working as it should. It appeared with the throttle in the idle position, the waste gate looked to be almost fully open (not closed as the Rotax video shows). Also in viewing the Rotax video I noticed that I didn’t secure the bowden cable to the servo unit the same way as was dictated in the video and I didn’t torque the cable capture bolt to that specified. So out came the servo motor which wasn’t;t fun since it required some crawling under the instrument panel.
After getting the cable out of the server motor I noticed that the spring that sits inside the collar where the cable attaches wasn’t there. Ahhhh that’s what that spring was that I found a while ago. Fortunately I had found a spring a while back on the floor of the cabin and was wondering where it came from. Good thing I kept it. So with the spring installed. I pulled the cable tight to close the waste gate (as shown in the video) and torque the capture bolt to 22 in lbs. I also verified that the brass bushing was in between the cable and the bolt prior to putting in the bolt. I then went out to the gate gate and adjusted the nuts on the end of the cable to remove any slack, plus about 1-2mm to put some tension on that spring on the server motor. Lastly was to move the cable sleeve to about 25mm from the servo motor case and crimp it onto the cable and then attach some safety wire onto it and the slit on the servo motor body. I had rigged up something similar, but I feel bette that it’s what Rotax intended now.
Once that all looked good I turned on the master and moved the throttle from idle to max power and watch the servo move as well. Now with the throttle in idle position the waste gate is fully closed (spring attached to waste gate is stretched).
Servo motor redone with safety wire to secure cable to motor body and the spring is installed inside the metal sleeve where the cable enters the motor body. Also in this position of the server the waste gate is fully closed.
Well I safety wired the adjustment nuts on the waste gate side, but looks like I need to redo it. The wire should be tight against the nuts on both sides and no slack in the wire. Also there is a nylon tubing inside the spring that connects to the waste gate. That provides vibration dampening.
UPDATE 8/15/2021
I redid the safety wire on the adjustment nuts for the servo waste gate cable.
I installed the 2 com and transponder antennas. On the top I have a straight RAMI AV-10 (Com1), and on the bottom is the bent whip RAMI AV-17(Com2) and the blade RAMI AV-74 (Transponder). I also ended up making new rubber gaskets for the Com antennas to better fill the gap that the rivnuts make.
The transponder antennas was a pain to install because it’s has #8 studs that come up into the cockpit floor in the center console. I have a few wires and fuel lines that run there so access isn’t easy. Also because the floor is 2 layers it’s challenging getting the washers and nuts down onto the studs. I was able to carefully get everything together using some needle nose pliers. I also added some large #8 fender washers to each stud just to give some added stability to the antenna.
I cleaned off the paint from the rivnuts to give a little more area for the antenna to ground.
New gaskets for the 2 com antennas (top photo: new on the right, original on the left, bottom photo: new on the left, original on the right) that are a little thicker and also I made the holes for the mounting screws a little larger so it would fit around the rivnut.
Some photos of the mounted antennas. I used countersunk M5 screws that fit fine into the the supplied cup shaped lock washer. The original screws that come with the antennas are #10 I believe.
I started installing the battery. I forgot to bring the 6AWG crimper so I didn’t get very far, but I did get the SAE charge connecter installed so I can keep the EarthX battery on trickle charge. I hear the batteries are a bit finicky so best to keep it on a charger. The charger comes with a charge cable that connects to the battery lugs and then has an SAE quick disconnect on it. I purchased an additional cable that has some LEDs on it to indicate if the battery is OK or not. I guess the downside to this charge cable is that it draws a little current from the battery to run the LED..
The battery didn’t exactly slide in as I expected because it hit the flange of the cowling strip and the cam lock receptacle so it was too tight to slip down into the battery box. I had to loosen the 4 M6 screws that hold the battery box onto the firewall and then the battery slipped into place. Not too bad but kind of annoying. The battery box couldn’t really be mounted too much lower because of the throttle and choke cables exiting the firewall.
Battery is in, just need the crimper so I can put ends on the wires to fit the M6 screw on the battery terminals. I did mange to wire up the battery fault indicator though.
I used a few adel clamps to mount the charger port SAE connector to the engine frame. Seems like it should be convenient to get to through the cowling door. I also put some split sleeve cable protector on the wires since they don’t look like very durable wires.
I’ll continue work on the battery tomorrow when I have the crimper.
