It Flies (and Flight Testing)

This morning my wife and I drove out to French Valley Airport in Murrieta/Temecula CA. I took my wife for a ride to get some fuel and do a run-up of the engine. It was around 90ºF when I finally made it to the runway so the engine was running a little hot, but all looked good so I ask her to get out and I proceeded to the runway. I slowly added throttle and it responded well so I applied full boost power (115%) and then pulled back on the stick slightly at around 55 knots and just like that I was flying. The handling was very good. Pretty sensitive on the controls so it took a little getting used to. I wanted to fly more, but I noticed the oil temperature was jumping up to around 250ºF and then back down to around 190ºF which seemed a bit odd. My thought was a bad connection or faulty temperature sensor, but I didn’t want to risk damaging the engine so after only one lap in the traffic pattern I set it back down to further investigate.

Also to note was that after driving out to the fuel at the far South end of the field with a stop at another fuel station (that didn’t seem to work) I had some difficulty starting the engine. It cranked and tried too start, but would die. I thought maybe a lack of fuel so I tried adding choke, but no luck. I then took the opposite approach (too much fuel) and turned off the fuel pumps and set the throttle to idle and was able to get it to start after one or two attempts. After a bit of research it seems this is a know issue with the 914 when it’s hot outside. It will start up cold fine and will also start right after shutdown, but if you wait 5-10 minutes then it won’t start very easily. You then need to wait 30-45 minutes to let it cool and it then starts. The theory is that fuel in the carburetor bowls vaporize and there is also fuel vapor in the plenum chamber and that causes the engine to be too rich so it won’t start. Someone noted that turning off the fuel pumps prior to shutdown, letting the engine start to run rough due to lack of fuel and then kill it with the ignition will help minimize the issue. I’ll give it a try sometime and see how it goes.

Getting some AVGAS, there’s no Mogas on the field so using AVGAS for the testing.

Run up is done and all looks good.

A few more photos from the first flight day.

UPDATE 7/29/2022

I had a few issues since the first flight. One was that the oil temperature would be in the normal range (around 210ºF) and then suddenly jump up to over 250ºF in a split second. All other temperatures (EGT, cylinder temps, and oil pressure were perfect). While I’m not that great with engines I know a liquid (oil in this case) can’t actually heat up that fast. I figured it may be a bad connection to the sensor or a bad sensor rather than an actual over temperature issue. In any case I did treat it like it was actual and did what I could to fly while seeing what could be done to keep the temps in the normal range. It was indeed sporadic and not much could be done on the aircraft (lower RPM, more coarse prop setting, etc.) to bring temps down. I opted to keep the flights short where the temperatures were in this high range. I had check teh wiring and all seemed good. I decided to swap the oil temp with one of the cylinder temp sensors since they are the same and to see if the issue would follow. A run of the engine on the ground showed normal temps across the board so issue seemed better, the cylinder temp that I moved the sensor to was also normal. I also decided to disconnect the return line from the oil cooler and force in some oil with a syringe, just to make sure there was plenty of oil in the cooler… it seemed like there was as only a small bit was added until it came back out the thermostat where the line was disconnected. In any case so far the temps seem OK. They go up to around 235ºF after a bit of climbing after take off, but cool after going into cruise.

The other issue I had was the plane to want to bank to the left if I let go of the control stick. If I held pressure (to the right) to neutralize the ailerons the plane flew straight. To me it seemed like something weird with the ailerons. I checked all the rigging and also that the wing angles (wash out) all matched between teh left and right wings. I lowered the left flap about 5mm and it maybe helped a little, but was hard to tell. TAF said to add a trim tab to the right aileron which I really didn’t want to do… I wanted to find the reason for why the left wing was dipping, but reluctantly I added the trim tab and it does fix the problem. So for now I’ll keep it with double sided tape. Maybe something will come to mind to check.

In any case the plane flies very well. I’m getting used to the prop and the noises the plane makes. It’s very responsive and climbs like crazy on take-off.

The trim tab I made for the right aileron. I’ll need to get it painted and then rivet it on, but for now it seems to fix the left roll issue. To the life of me I can’t figure out why it wants to roll to the left though.

UPDATE 8/4/2022

After a few flights I noticed that the fuel pressure would very briefly spike up to around 5.3-5.4 PSI (Normal is 3.6). It would quickly come back down to normal, but didn’t seem right. I also noticed that the fuel pressure would sit around around 4.1 PSI when idling on the ground so I decided to adjust the fuel pressure regular down by 0.5 PSI. The adjustment is done by turning a set screw on the bottom of the regulator (CCW to decrease pressure, CW to increase pressure). So far it seems better. It has only spiked up maybe once or twice on the last 3 flights. It may also be that the UMA differential sensor isn’t working completely accurately when the airbox pressure gets higher. The fuel pressure sits pretty steady at 3.6 PSI while idling, but seems to fluctuate in a wider range when airbox pressure gets high or it could be the regulator over compensating for a change in airbox pressure. I think the engine should have data on the airbox pressure so maybe I can see if there are any sporadic readings of airbox pressure.

UPDATE 8/5/2022

Well the fuel pressure issue remained on my first flight today. For the second flight I figured I should make sure all was good with vacuum connections, etc to the fuel pressure regulator. All seemed good, but I noticed a little white residue around one of the brass fitting into the airbox. I put a wrench on the fitting and it was a bit loose so I tighten a bit so it was snug (there’s probably a proper torque value, but for now will do). This was a fitting installed by teh factory and had torque seal on it so not sure why it was loose. Anyways I figured it wouldn’t really help that much… boy I was wrong. The next flight the fuel pressure was nice and steady on teh ground as usual. I took off and started my climb up to 6000ft into the test area (about 5 miles East of French Valley Airport (F70). Watching the fuel pressure gauge I noticed vert small fluctuation between maybe 3.9 and 4.2 PSI (in flight the pressure seems to go up a bit from 3.6PSI). The whole flight which was a bit over an hour I expected it to jump at least once or twice, but no it stayed in a very small range. I flew 3 more times all about an hour each and same thing so it seems like the large fluctuation in the fuel pressure has been resolved with the tightening of fitting.

I’m still messing with the K factor on the FT-60. I had set it to the default 68000 and was reading very low (3.1gal/hr in cruise at 31 MAP and 5000RPM – 75% power). It’s been a bit difficult to accurately set it because the fuel gauges are so in accurate. They’re only somewhat accurate when parked on the ground so that’s what I’ve been trying to use as a basis for how much fuel was used and then compare that to the fuel calc page on the GDU. I think I’m getting close now though. I set it to 55000 and will test on Sunday. The Garmin manual has a calculation for adjusting it… Corrected K-Factor = ( [G3X reported fuel used] x [previous K-factor] ) / [actual fuel used]. I’ll see if I can accurately determine “actual fuel used” and then this should help get me much closer, then it may just need some small adjustments to get it perfect.

UPDATE 8/7/2022

I’m at 23 hours now so in 2 more hours I need to do my 25 hour inspection which is mainly an oil change and going through the plane and just making sure all is good. I’m going to try to get the 25 hours tomorrow morning so I can start the inspection later in the day and do the oil change on Tuesday and then hopefully get some flying in on Tuesday evening. The plan is to wrap up the 40 hours by Saturday or Sunday and bring the plane home to Torrance. The plane has been flying really great. My #3 EGT is a little high so that would be nice to fix, but it’s within spec so I’m not super worried about it. I think the carburetor is a little lean so I need to verify the placement of the circle in the carburetor. I also have a buzzing sound in the cabin at certain RPMs which I think might be something with the rudder pedals. I sounds like a washer or bolt vibrating. Once again it’s really just an annoyance and nothing major so if I can fix it then I will otherwise it may just be something on the squawk list that will eventually get resolved some day.

One thing that is slightly important is that I have the newer cylinder heads (suffix -01 as they are called), this is identified by having the temperature sensor on the top of the cylinder head rather than on the bottom. I knew this and I read it quite a few times in the Rotax Installation Manual, but it suddenly dawned on me that the newer placement of the cylinder temperature sensors also means that they are not measuring cylinder head temperature, but instead coolant temperature. What this means is a reduction in the max temperature on the sensor gauge reading displayed on the GDU from 275ºF to 248ºF and technically it should read “Coolant Temperature” instead of “CHT”, but since I used the CHT pins on the GEA there’s no way to change the label. I suppose I should move them to one of the Misc Temperature pins that can have a custom label and then label it as “Cylinder 2 Coolant” and “Cylinder 3 Coolant”. The reduction in max temp didn’t do anything since the temperatures where always well below that, but the Rotax Manual stressed that you need to make this change and also notated that they are coolant temperatures and not CHT readings. The later I’m not really sure how I’ll implement. Anyways I thought it was interesting and funny that I have looked at that verbiage and never really caught on above the change in what the sensors are actually measuring.

UPDATE 8/9/2022

Today I did the 25 hour inspection. The inspection has many points (listed in the Sling POH, propeller manual and the Rotax maintenance manual) that I’ve already been checking after each flight, but I did a bit more involved look at a few things like verifying the torque on the spar bolts, the engine mount bolts, etc. I also did a check on the prop for cracking and wear on the trust bearings. The last bit of the inspection was to go over the engine and do an oil change. Everything looked good and the oil change went fine. The only issues that I found was that the water cooler must have been touching the exhaust so it melted a bit of the top and a few fins. I adjusted it and there’s now about 1/2-3/4″ of clearance which isn’t great, but should keep it from touching. I’ve also been checking it before each flight to make sure it’s not any worse. I’ll do a proper fix when I get the plane back home in a few days. The other thing to note was that looking at all the plugs, most were a sooty black which means that the engine is running too rich. I don’t think there is a simple mixture adjustment on the carbs so I’ll have to look into how that is adjusted. This could also have happened prior to my setting up the carbs and doing the carb sync, but most likely not. I cleaned the plugs so I should be able to find that out at the 50 hour.

UPDATE 8/12/2022

The past few days was just getting time in the plane and making sure all was working as expected. Today marks 40.2 hours of time on the plane so I made my log book entry and will be flying the plane back on Sunday to Torrance. I have a few remaining issues, but they are mostly just annoyances and not critical to safety. First issue is that the oil temperature slowly climbs up to 238-240ºF on climb out over around 3000ft. The work around has been to set the propeller to 5000 RPM (cruise), pull the throttle to 31 MAP and lower the nose a little to get 80-85 KIAS. The oil temp then come down pretty quick, all other temps are great. After it reaches normal I haven’t seen any issue with climbs even at climb RPM (5500) so it’s a bit odd. I may try a new oil thermostat to see if maybe this one is not opening all the way. Second issue is that the fuel pressure seems to fluctuate. I thought I had this fixed, but it has come back up a few times since. When it’s behaving I see very steady press on the ground and once up to cruising altitude it fluctuations a bit between 3.5 and 4.2 (and typically hangs at 4.1) which is fine. When it gets crazy it will rise to 5.5 and then drop to 2.3 and then bounce around between that for a bit then settle back down. Since the UMA sensor is calculating the difference between airbox and actual fuel line pressure then it could be any of those 2 things that is fluctuating and causing the problem (or it could be an issue with the sensor itself). It may be heat related as well since it seems to happen after the plane has been flown a bit. So to figure this out I’ll have to rig up a sensor to look at airbox pressure and another to look at fuel line pressure and then when the UMA starts fluctuating I can see what exactly what is causing the fluctuation. I’ve eliminated the fuel pump and fuel tanks since it doesn’t matter which one I’m on when the fluctuation starts. I’ll also take look at the gascolator because that is common between both fuel feeds, maybe there’s some debris in there. Last issue is that the PDF heading sometimes shows yellow and says “miscomp”. SO far it’s only happened in a steep turn and on a fairly rapid descent (1500-2000FPM). I emailed G3 experts and they said it’s because the pitch roll is off on the ADHRS. The G5 doesn’t have the issue so I think that may be the case. I think that when I added in the backing plate to the ADHRS to get it to pass the vibration test I may have forgotten to redo the pitch/roll calibration or I did a crappy job of it. So I’ll just level the plane and do the calibration again which also means doing the compass (magnetometer) calibration as well.

It’s Worthy of Air

Woo hoo the plane passed its airworthiness inspection today. Now on to the flying. While flying is fun, for me the first flight is going to be a bit scary and stressful. I feel pretty good about the engine. I have over 3 hours of run time on it and it seems very strong. Even the inspector said it sounds really good… for a Rotax :-). The flight controls are pretty much what they are. So long as all the retainer nuts are tight on the torque tubes nothing should change. The one part I don’t have too much time with it the propeller control. I did run some high RPM tests and it seems to work, but my confidence level is a bit low with it, just because I haven’t used it much. Granted it’s pretty simple to use, but I just don’t know what to expect from it. I do have some time in a more conventional constant speed propeller system from flying Diamond DA40’s, so hopefully that will help in troubleshooting any issues. All else fails I can put it in manual mode and adjust the propeller as needed and land. I’m really hoping though that Jean can make it out to give me a hand even for an hour or so, but I know Oshkosh is next week and he’s super busy. Any ways I’m thinking of heading to Temecula early Thursday morning (with or without Jean) to attempt some flying.

It’s airworthy. Now to get some air under the wings. My test area is a rectangle to the East of French Valley. It’s a 30 mile, by 11 mile rectangle so at least I won’t be flying around in a tight circle for hours on end.

Off to Temecula

This morning we loaded the plane onto a flat bed and made the trek out to French Valley Airport in Temecula, CA. French Valley is almost 90 miles from Torrance Airport and mostly over highways, but California roads aren’t all that great. I followed the truck out to make sure everything stayed in place on the trip. I’m glad I did. We had a few of the tie downs come loose at different times so I flagged the driver down to stop so we could resecure things. The trip took almost 2 hours, but the plane arrived safely at Temecula. Bradford from Aircrafters was there to help me move into the hangar that Jean found for me. It was nice to have a place to work on the plane and set up some tools.

Towards the afternoon Bradford stopped by with a few others to help put the wings on. I felt kind of bad because I know they have done this quite a few times and I was just slowing them down by trying to help, but all went fairly well. I still need to torque down all the bolts and get a few other things put back together.

The guys from Torrance Sling helped to load up the truck. The wings barely fit with the steps on. I thought I was going to have to remove them, but we were able to get it to work by only removing the bolt that secures the step to the support and then zip tying the step up. The extra 1 or 2 of clearance was enough to get he second wing onto the truck.

I thought I was going to have a heart attack watching the plane bouncing around on the truck. Some people were taking pictures of it as it drove by them. I suppose up to this point it’s the fastest the plane has gone… ha ha.

Made it safe the French Valley. I did notice some scratches on the bottom of the fuselage though. I think maybe one of the things I used to secure ether flaps and ailerons from moving must have rubbed on the fuselage either when we off loading the wing of maybe over some of the larger bumps. Anyways it’s just a few scratches that can be fixed later, there were no dents or damage to the skin itself.

OK so now just need to get the plane back together and get ready for the inspection.

Getting Ready for Temecula

Dan and I removed the wings today and I’ve been doing a few small things to get it ready to go to Temecula for the inspection and flight testing. The truck is scheduled for 7/13 and I spoke with Mike (the DAR) and he should be able to do the inspection on 7/18. Hoping all goes well. I still have a few more things to do on the plane, but should have plenty of time with the moving day pushed back a week.

And the wings are off again. Also I removed the wheel pants and the bottom com antenna since the wings get stacked under the fuselage when it’s loaded on the truck. I’m also started to put a coat of ceramic/wax on the paint to protect it because it will be subject to more dirt and contaminates now. I do have a cover, but that only covers the canopy back to around the top com antenna.

Parachute Install

Time: 9.5 hrs

Well I was all set to go ahead with teh test flights without the parachute and then I get an email from Jean saying that a few parachutes and rockets arrived. I went ahead and picked up a rocket and a parachute and started to work out the install. The Installation Manual that comes with the parachute is rather light on information on how to actually install the rocket and parachute. The Sling 4 manual does have some information on installing the parachute so that didn’t seem to be an issue. Fortunately Jonathan at the TAF build center had a copy of the Rocket Installation manual which is mentioned in the other installation manual, but not available from the Status 07 web site. It answered quite a few of the questions I had about installation of the rocket.

I started the install by roughing out the cable run for the activation handle and also removed the activation handle from the cable since I have to pass it through a small opening in the instrument panel. I also drilled the hole in the luggage area floor and mounted the rocket mount onto the box. I had previously installed AN3 nut plates to use to secure the rocket mount to the parachute box, but the AN3 screws fit too loosely in the holes of the mounting plate so I decided to drill out the AN3 nut plate and drill the main hole to fit the M6 screws that came with the parachute to mount the rocket. I’m planning on finishing up the cable and parachute install tomorrow.

After getting the pin pushed back I needed to unscrew the plastic piece from the handle and then thee cable end was able to be removed. he hole in the panel is only large enough for the cable end to pass through so I had to remove the handle. Also this allowed me to drill a bit smaller whole in the luggage floor since I didn’t have to try to pass through the larger connector that mounts onto the rocket and could instead pass the handle side with the smaller connector through.

I got the parachute roughed in as well, though Jonathan said that I need to pull the orange part of the connection out of the parachute bag and more into the tray. I’ll rework this tomorrow and make sure the cables will not get caught on each other.

The hole in the luggage area floor is drilled and I installed a grommet to protect the cable. I didn’t put in the rocket yet, but I put in the end that connects to the rocket so I can get an accurate idea of how the cable needs to run. The cable runs pretty much through the center section of the aircraft. I went through a lightning hole under the rear seat and then straight back through another lightning hole before it goes under the luggage area. I’ll install a mount for the cable and some edge protector.

UPDATE 6/3/2022

Today I finished installing the bowden cable between the activation handle and the rocket ignitor. It mainly runs through the center of the aircraft except when it gets to under the rear seat. I put it through a lighting hole on one of the side ribs and then another lightning hole in the rear rib. I did this just to stay clear of the rudder cables and the rear elevator control horn. It also allows for a bit gentler bend in the cable before it bends up to go through the luggage floor.

I also put in the tie wraps that hold in the soft parachute bag, which was kind of a pain and reworked the steel cables that attach to the base line of the parachute. The last bit to do is install the rocket which I will see if someone from TAF can give me a hand doing next week.

The fully assembled activation handle. The L shaped piece I didn’t have so Jonathan gave it to me. I originally had 2 other pieces that didn’t seem to work for the installation.

The activation handle is installed. The cable ended up being the perfect length so no need for looping it around as I thought I was going to have to do.

Starting to install all the zip ties to hold the parachute bag in place. I found that it was easier to start the zip tie from the center holes and pass it through towards the outer edges of the parachute box. This makes it much easier when you then go to the box to pass the zip tie through the loops in the bag and then back into the hole in the box because you aren’t having to try to squeeze your hand behind the bag and find the hole in the parachute box. There isn’t much room to work in the box, especially trying to reach the ones at the very bottom. Also I found that I didn’t need the top holes because there’s no loop in the parachute bag at that point.

This is the top view looking down into the parachute box with all the zip ties in place. I then pushed the bag hard against the box wall and went back to the luggage are to start pulling the zip ties tight. Be careful you put the correct tail of the zip tie into the corresponding zip tie head. It easy to mess up since there are so many zip ties and if you mess up and have to cut one then you may have to start all over because you won’t be able to reach inside to rerun it. Fortunately I didn’t mess it up to find out how difficult it would be, but I would imagine it wouldn’t be fun.

All done. I cut the tails off as close as possible to the heads and then filed down the tails so there were no sharp edges that you can get cut on. I wish I could have found black zip ties, but this is all Home Depot had in this thicker size and I need to get this finished this week to stay on schedule. Oh well grey looks OK I suppose.

I got these at Home Depot in the heating/AC section. They are a bit long, you probably just need 2 feet or so to make its easy to be able to pull through enough to get through the bag and back into the box. I liked these because they are wider than typical zip ties.

I was sable to pull a little more of the main line out of the bag so that it reached up into the tray I reworked the steel cables so that they didn’t tangle at all and spiraled into the center. Zip ties help keep things organized and tightened down so they don’t move around. The zip tie will just break when the parachute opens so no need to use anything with high strength pull rating. I’m also going to stuff in some foam or something to keep the bag from moving. even though it’s strapped in it seems to move a bit because it’s just fabric.

Now I just need to prep the rocket and get that installed. Will do that next week.

UPDATE 6/7/2022

Today I prepped and installed the rocket, finished up the parachute connections and connected the bowden cable to the rocket ignitor. Getting the rocket ready to install and installing it was a bit nerve racking, though it’s fairly difficult to get it to ignite, there’s still a chance you can do it and potentially get hurt pretty bad. Fortunately all went well and the rocket got installed fine. It did take me a few trie stir get thee safety wire installed on the connection two the ignitor.

Thee cables and ignitor is installed on thee rocket. You also have to install 2 small strikers into thee end of the rocket before putting the ignitor onto the end. the manual also calls for silicon on the strikers and O ring. I used a temporary zip tie to hold the cables down while I pushed this into thee rocket mount which was already mounted in the plane. It may bee easier to do this and thee plastic tubing (seen later) with the mount out of the plane, but then you’re messing with the live rocket for longer.

NOTE: Whatever you do, do not pull the far end of the ignitor *with the cut out for the Bowden cable attachment) with any force or the rocket will ignite.

In the photo you can barely see a pinkish seal between the rocket and the rocket mount. This is a vinyl tubing that needs to be stuffed in between the rocket and the mount. The secret to get this to work, I found, was to heat up the tubing and stretch it out. Then bend the tubing in half to find the center and center that on the side of the rocket where the cables don’t come out (the front side of the rocket). Get the tubing pushed into that area first then use a wood dowel or block and tap around the rocket to push the tubing in around it. As you work towards the aft side of the rocket (the free ends of the tubing) the tubing will start to slip in around the rocket. I had tried starting on the aft end with the free end of the tubing first, but it pushes the rocket too much against the mount of the forward side that you can’t get the tubing in.

In the previous 2 photos you can see I added some spacers around the parachute bag to keep it from moving too much. It’s strapped down to the one side of the box, but since it’s just a soft cloth bag it does still move a bit. I used some left over 1/2″ insulating foam and just stuck it back too itself to build it up thicker (it seems to stick very well to itself). I didn’t put any on the side where the rip cord is so as to not interfere with that opening up.

The rocket is connected to thee rip cord part of the parachute. I used a bit of blue locktite on the clamp that int connects to as well was the large carabiner that connects the base line of the parachute to the steel cables. So that part is done.

The Bowden cable is connected to the rocket ignitor. It’s important that you pull down on the cable so that the collar of the fitting on the cable comes through the end of the connector. Also use some locktite on the set screw. It’s a bit scary pulling down on thee cable knowing that you could possibly ignite th rocket, but the end of tech cable has a stop so you can only pull it a little bit and probably not enough to activate the rocket. Also you want to make sure you pinned thee activation handle (on the other side of the Bowden cable) so that you can’t accidentally have the cable shorter and cause the cable to pull the ignitor as you install the connector.

Got the safety wire installed on the connector and also put the heat shrink over the set screw of the connector. There are holes in the connector and the ignitor to install the safety wire, then you wrap the wire around the whole bit a few times and end with a twist in the wire.

So now the rocket and parachute are pretty much down. I just need to install the skin on the fuselage and the cover inside ether interior.

UPDATE 6/8/2022

All done. It came out pretty good. There’s a few spots that scolloped a little, but not too bad. I added two more rivets to the front edge to minimize any scolloping there. I put some neoprene foam on the inside edge of the parachute cover which seems to work pretty well, but I might add some clear RTV around the outside edge just to make Sure it’s all sealed up. I’ll also need to fill and paint the rivets at some point, but dosesn’t look too bad as is.

Weight and Balance Complete

The weight and balance is completed for the plane. Since I’ve been waiting almost a year for the parachute I’m just going ahead without it. Once I get it installed I’ll just have the weight and balance redone or maybe the new W&B can be figured out. In any case the plane is slightly nose heavy without the parachute. My CG is at 1858mm and from the POH the most forward CG allowed is 1859mm. If you put a pilot and some fuel in there the CG moves forward a bit more so after some weight and balance calculations it looks like if I put 3 or 4 lbs (1.4 – 1.8 Kg) of weight in the luggage area that will keep my CG in check for my flight testing (single pilot/30 gallons of fuel). I’ll have to be a bit more mindful of the CG and do W&B calculations until I get familiar with the plane. Fortunately Firelight has W&B and I put all the data in there so calculating W&B is very easy.

During the W&B there was a bit of a mishap. The left wheel rolled off the scale and the rudder hit the hangar door. I’m hoping that they will be able to get most of the dent out and get it fixed soon so that I can get it down to Temecula to get the Airworthiness certificate and flight testing started.

I had a feeling something was going to happen. W&B was really the last thing that needed to be done on the plane, but now this needs to be fixed. Oh well accidents happen, hopefully will be fixed soon.

Weight and Balance doc for the plane. The CG envelope doesn’t have a few data points in it, but I guess it’s fine for its purpose of displaying the current CG within the envelope.

UPDATE 6/2/2022

The rudder got fixed and came out really well so all is back on schedule again. Also we were able to rework the weight and balance with the numbers that was obtained from the weight and balance session and found the plane to be just slightly forward of the max forward CG (the original weight and balance was done for a Tsi which is slightly different that the Sling 4) so when the parachute and rocket are added it should work out OK.

Fuel Flow Rate Test

A fuel flow rate test is required for airworthiness of an experimental aircraft. Since this is a known design the system should be designed well enough to meet the requirements which for a pressurized system is 125% of the maximum takeoff consumption (it’s higher for gravity feed systems), but good to verify on a new build anyways.

To start the aircraft should be in a high take-off angle which was the tricky part, I did this by having someone push down on the tail as I stacked blocks under the nose wheel. Next was to disconnect the return fuel line hose at the fuel tank put that hose into a contain (mine is measured with ounces and milliliter markings, and run the fuel pumps for a specified amount of time. I ran the pumps for 60 seconds and got right around .5 gallons of fuel (so around 30 gal/hr) of flow at each wing. In the manual the 914 requires 8.7 gal/hour (so we’ll call it 9 gallons/hour) at takeoff (5800RPM), and 125% of that is 11.5 gal/hr. With a fuel pump flow rate of around 30 gal/hr that is still is over 200% of the flow rate required by the engine at take off. So looks like all should be good for the fuel flow of the system.

Prep for Weight & Balance

I’m scheduled to get the weight and balance done over at TAF Torrance tomorrow so I wanted to get the plane prepared. Nothing too crazy, but I wanted to get the fuel drained out as much as possible and also put on any fairings, etc.

I drained all the fuel from the left tank and left about 3 gallons in the right. We’ll have to drain that out once I get the plane taxied over there. I also had to put on the main wheel pants, the wing fairings and the top cowling as well as some interior panels. It should be good to go now so long as it starts tomorrow. I also removed anything that isn’t permanent from the cabin. I left the floor mats though, those can easily be removed if needed.

Everything is together. Of course it will all have to come apart to go to Temecula.

Of course the right wing fairing didn’t want to fit. The issue is the hole where the step support comes through. I wasn’t able to connect those when I fit the fairings. I just had to open up the cut out a bit so the fairing fits. I’ll clean it up when I take them off. I’m also wondering if I should have had the fairings painted blue and not silver… will worry about that after the test flights are done.

Pitot/Static and Transponder Check

Time: 2 hrs

Today Greg stopped by to do the transponder and pitot/static check. The transponder check was super fast. We just put the transponder in maintenance mode which can be done from the PDF screen. After the transponder checked out OK they set up the test equipment for the pitot static check. This was just a quick check and not a full test like what his needed for IFR certification. Everything checked out fine. The airspeed and altimeter reading were accurate. The only issue Greg said was that there seemed to be a leak in the system which didn’t affect the accuracy of the gauges, but needs to be resolved prior to doing the full pitot static check for IFR.

After Greg left I checked the system using a vacuum pump and pulling a 10 in Hg vacuum on the system. I first verified the rear fuselage tubing and fittings by connecting into the “T” I have that goes to the alternator static port. All that checked out fine. I then added back the alternate static port, I figured this is where the leak was, but I didn’t see any leak there either. Lastly I connected directly to the tubing that goes up to the ADAHRS and G5 and that’s where I noticed a fairly good leak. Through some further testing it came down to the fitting on the G5. I used the nylo-seal fittings which are nylon. I guess if you tighten them too much the threads will leak. The fix was to loosen the straight fitting in to the G5 by about 1/4 to 1/2 a turn.

So with this done and having the transponder check in the airframe log book, the last thing is to get the weight and balance done. I’m hoping to get that done next week.

Painting Window Borders

Time: 4hrs

Over the last few days I masked the windows and prepped them to be painted. This is required (in the manual for the Sika adhesive) so that the UV doesn’t deteriorate the sika and cause it to not hold the plexiglass windows. The manual states to paint over the sika area and extend that 2 times the thickness of the material out from the edge of the sika area. So basically if the material is an 1/8″ thick then you extend past the inner edge on he window by 1/4″. I also tried to even out the borders so it was a fairly consistent width around each window.

I forgot to take photos while I was doing the work, but nothing out of the ordinary was done. I remembered when I started to take the tape off. I used 3M 1/4″ vinyl tape which worked really well. It bends nicely around the corners and I had no bleed of the black paint onto the window edge or the canopy edge. After I put down the 1/4″ tape and was happy with it I just covered the whole plane in thin plastic and cut out for the windows. I then used scotch painter tape to tape that down around the existing 1/4″ vinyl tape. Once all was done I sanded the area to be painted with 220 grit paper and then clean well with SEM cleaner. Carlos came by the next day and sprayed the Imron gloss black paint. Most people use satin or matte finish, but I liked the way the borders looked prior to painting and that was a glossy look so I figured to keep it the same.

This is the tape I used for masking the edges of he painted areas. The tape works really well.

After a day of drying I removed all the masking tape. The paint is still sticky at this point so it’s a good time to remove the tape, but you have to be careful not to touch eh paint since it will leave a finger print or mark.

I’m happy with the way it came out. It’s hard to see in the photos, but the lines are very clean and the gloss looks good with the rest of the paint on the plane.

So with that done I only have a few more things to do. I need to let the paint dry for another day or 2 and then will attempt to do the magnetometer calibration again. Jean (from TAF) gave me a few pointers so I think this time should be successful. I also have an issue withe the ADAHRS failing the vibration test between 3000-3100 RPM so I need to figure that out. I’m going to try to get the prop balanced and see if that resolves the issue. I may also need to just add some material behind the rib that the GSU mounts to and also verify that the bolts are torqued.After that the plane is pretty much done…. well minus the parachute with I don’t think I’m going to get any time soon.