Re: Building the EX3 - Tips & Hints
FUEL TESTING
Watch a video on this here https://youtu.be/1u8okDP7d0Y
To test your FUEL FLOW ...... go to my post #171 here https://forum.cubcrafters.com/showth...ll=1#post25123. The form to calculate it and a good link to the EAA website video/seminar on this is posted there.
FIRST, turn your fuel valve selector to OFF position.
After weighing the plane for the weight and balance calculations, I put 2-1/2 gallons in the right tank first after putting the plane in level, flight condition.
NOTE: I found that this little 46" high stepladder is absolutely PERFECT for leveling my EX3 with 31" tires and Baby Bushwheels! Just put the level on the inside of the door opening and the bushwheel in the paint can holder at the top of the ladder and done! You can always add some shimming material if you need to raise it or change main tire pressures as well. I use tire pressure to level the plane left to right when working wing rigging, weighing, etc.
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With the plane in level flight conditions, the wings are of course at a positive angle of attach so the fuel will go to the back of the tanks. With 2-1/2 gallons in the tank, I marked the fuel sight gauge with a sharpie (Gordon Gilchrist gave me this idea. Thanks Gordon). You can see in the photo below that it just barely came into the bottom of the sight gauge.
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Turn the fuel selector valve to the RIGHT tank.
With this small amount in the tank, I can check for any leaks anywhere before putting alot of fuel in because.......sure enough......I had a small leak in the quick drain at the rear of the fuse. It didn't leak at first but after I used the fuel strainer cup to check for fuel at that location, it starting dripping.
So, I drained the fuel out at the gasolator drain and removed that quick drain fitting and sure enough, there was some crud on the oring. From now on I will really clean those orings before installing those fittings but at least I didn't have 44 gallons of fuel I had to drain.
I leave off the covers at the bottom side of the wing roots until after I've done this so I can look and feel up in the wing root to check for any leaks. I just taped those piece on for weighing earlier.
Move the fuel selector valve to the LEFT tank next.
Next I put 2-1/2 gallons in the left tank and checked for leaks anywhere in the left wing root. Also look real close UNDER the fuel selector valve to be sure there are no leaks around that valve. It will probably show up on the outside of the fuse under valve area on the outside of the fuse and where the boot cowl meets the fuse. Keep a close watch here for several weeks to be sure there isn't a slow leak there that seems to be occurring alot with these valves because of dirty or faulty orings inside. Spin the fuel valve around several times to all the positions.
If everything looks good at this point and I have marked the 2-1/2 gallon mark, I then went to the gasolator with the fuel selector valve set to the right tank....and drained all the fuel out that I could. In the level flight position, I got just over 1-1/4 gallon back out of the 2-1/2 gallons that went in.
That means that in level flight, there would be 1-1/4 gallons unusable in each tank or 2-1/2 gallons total out of the 44. HOWEVER, when flying.....the vented fuel caps pointed into the wind will pressurize the tank and most likely force more fuel out??? You think? However, read below after I filled the tanks to see that the tanks REALLY don't hold 44 gallons!
I understand that the engineers calculated that there would actually be 2-1/2 gallon each tank....or 5 gallons unusable total (39 usable out of 44 total) because of fuel available during certain maneuvers such as a hard turning, high angle of attack situation such as a climbing turn take-off. So I will still set my G3X up to show a total of only 39 gallons of usable fuel but I do know that I will have 2-1/2 gallons more. I plan to fly a tank dry completely during flight testing just to see how much fuel will remain in flying condition (level, stabilized flight).
If all is good and after having done all this with the 2-1/2 gallons in the tanks, move the fuel selector valve to OFF and I'll go ahead and put 2-1/2 more gallons in each tank and again mark the fuel sight gauge where it is exactly. So now in level flight, I will know EXACTLY when I have 5 gallons and 2-1/2 gallons in each tank.
You can see that the 5 gallon mark is actually just under the 1/4 mark on the placards.
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The next thing to do is to fill the tanks completely full and let's see exactly how much the tanks hold. I already have 10 gallons in....so should be able to get 34 more gallons in BUT I WASN’T ABLE TO.
I WAS ONLY ABLE TO GET 32.5 MORE GALLONS IN THE TANKS SO THAT MAKES A TOTAL FUEL CAPACITY OF 42.5 AND NOT 44 SO IT’S 1.5 GALLONS SHORT!
I was extremely careful when filling the tanks. The fuel pump I was using at my airport had just been calibrated 2 weeks ago, so hopefully it was right on. After filling 5 gallon portable fuel tanks with this pump and putting in the airplane, When I filled the tanks the rest of the way, I filled 1 side to the rim and then went to the opposite wing and filled it. I then returned to the first wing and topped it off again since some fuel can cross fill to the other side while I was filling.
THE FULL FUEL CAPACITY THEN IS 42.5 WITH ADVERTISED 5 GALLONS UNUSABLE IN ALL CONFIGURATIONS THAT MAKES 37.5 GALLONS USEABLE AND NOT 39 AS ADVERTISED. I do know from my test though that actually there was only 2.5 gallons unusable in the static, level configuration for 40.0 useable.
Maybe the advertised 44 gallons would be the capacity of the fuel tanks in the level flight attitude but we don’t fill the tanks in that attitude but the 3 pt.
PLEASE: IF SOMEONE ELSE DOES THIS TEST WOULD YOU PLEASE POST YOUR RESULTS.
UPDATE MARCH, 2020: I DID THESE SAME TEST ON MY NEXT AIRPLANE AND GOT DIFFERENT RESULTS. I DID THE TEST EXACTLY THE SAME SO I HAVE NO IDEA WHY THE RESULTS WOULD BE DIFFERENT BUT HERE IS WHAT THE NUMBERS ARE ON THIS AIRPLANE.
I put the 2-1/2 gallons in each tank to check for leaks. 5 gallons in total.
Then, in the flight level position, I drained as much fuel as I could through the gasolator with the fuel selector switch on BOTH. I drained 3-1/2 gallons out which means only 1-1/2 gallons remained in BOTH TANKS (so about 3/4 of a gallon on each side).
SO, in this case.....in the static, level position the unusable fuel is only 1-1/2 gallons.....not the advertised 5 gallons. NOTE that that does not necessarily mean it will be this in a configuration other than static, level position.
NEXT, I started the engine and ran it for about 15 minutes to get to the airport fuel pump and filled the tanks. It held 33.9 more gallons so that means it held 43.9 gallons plus the amount I had burned starting the engine and running it to the fuel pup......probably less than 1/2 a gallon. So with the tanks and fuel lines full, it did indeed hold 44+ gallons full.
Both tests were done identical but with different results. I have no idea why so test yours to see what it will do.
FUEL FLOW CALIBRATION
The first few tanks of fuel I’m sure to reset the fuel used on the FUEL tab when you have the engine management page open. After refilling the tanks completely, I compare the actual fuel used to what it says was used on this page. I do this for several tanks of fuel being sure to reset it each time. Then I used this formula to then go into the CONFIG menu of the G3X and “calibrate fuel flow” using the formula here. Then keep track of several more tanks and make any further adjustments needed until it continually comes in with the actual fuel used matching what this page says.
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PITOT TUBE WITH AOA
If you have the G3X with the GAP 26 Pitot with AOA then you will need to install it. Hopefully you left enough of the blue and green tubes so they were long enough to stick down through the mast so you can grab it and push it into the pitot tubes. The BLUE tubing goes to the FRONT aluminum tube coming up from the pitot and this is the pitot tube. The rear one has the GREEN tubing of course and this is the AOA tube.
You can see this on page 34 of the EXECUTIVE GLASS MANUAL.
You will need to cut about 8" off the aluminum tubes coming up from the pitot and heat the blue and green tubes so soften so you can push over the pitot tubes. The length callout in the manual is for about 5.0” on the shorter, aft tube for the AOA and about 5.50” for the forward, Pitot tube on the Gap 26.
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You locate the bracket you installed on the wing and then cut out the center where the mast will go as well as the inspection hole to the outside of that. The mast will go up, into the wing and then down through the bracket and you locate and punch out/burn the holes in the fabric and install the 4 screws from the mast into the bracket.
Then reach in and push the blue and green tubes down through the mast and put them on the pitot and then screw the pitot into the mast with the 4 screws.
In the manual you will see that the BLUE tube is the pitot line and goes on the longer, FRONT (forward facing) tube going into the GAP26 pitot and that leaves the GREEN tube for the AOA going onto the shorter, AFT (aft facing) tube on the Gap 26.
I also put some silicone around the connection of the blue and green tubes onto the aluminum pitot tubes just to help seal and keep them secure. I let that dry overnight before pushing the pitot up into the mast and securing.
AUTOPILOT SERVOS
Before securing the belly pan, we need to finish the installation of the servos and install the pilot seat.
NOTE: You will have to go into the configuration menu to AUTOPILOT and change the direction of the PITCH servo to “REVERSE” as it act backwards from normal. Go to the Installation Manual to around page 700 for instructions and on page 705 then test the autopilot.
PITCH SERVO
Follow the instructions that comes with the pitch servo kit. You have to install the cable onto the servo and onto the elevator cable. It isn't that hard but hard to understand. The cable has a little metal "tit" on it in the middle. Just turn the servo round part until the hole in the center of it is facing down and put that cable "tit" into that hole. Then as you look up from the ground, route one wire around the left side of it (under the cable guards), keeping it in the slots. You will have to go under 2 of the cable guards and leave it sticking out towards the rear of the plane up at the top. This cable will attach to the elevator cable there on the aft side.
Do the opposite with the other cable. Note the instructions say to have the cable a "minimum of 1 complete wrap". This always confused me on how to get each cable a full wrap but it isn't "each cable"....it's just the "cable". So if the tit is on the bottom and 1 side wrapped 1/2 way around and sticking out 1 side at the top....the other will wrap 1/2 way around and be sticking out the top in the opposite direction.....that IS 1 full wrap.
Cubcrafters ships some better, metal pieces that holds the 2 cables together. Use them instead of the white, plastic ones that come with the kit from Dynon. You can see 1 side has a bigger slot cut in it and 1 side smaller. Just put the bigger 1/8" elevator cable on the big side and the smaller, servo cable on the other. Just attach one side or the other and before tightening up the 2nd cable, pull it tight but be sure that tit is still in the center of the servo round part and that it is centered downwards, right over that bottom cable guard.
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Also not that the cable from the servo will be very close to touching that 1 fuse cross tube.
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To make it work and keep the clearance.....look here how you install the cable clamps more upwards...towards the floorboard bottom. Just move the clamps back and forth (or front and aft I guess) until you are sure you have good clearance of everything and check when you move the stick full forward and aft.
By pushing the clamp up sort of parallel with the elevator cable, it will bring that little cable up high enough to not rub on that crosstube.
You have to do that with the rear one as well.
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ROLL SERVO
This one is much easier. I taped the correct rivet to the torque tube back during fuse construction so I wouldn't have to look it up and hunt it down now.
Center your stick/ailerons and then look down into the seat base so you can see the torque tube and where the servo arm attaches. We loosely installed the bracket and arm onto the torque tube during the fuse build. With the ailerons/stick centered, move the bracket on the torque tube until it's perpendicular (90 degree angle) to the servo and so that the arm coming up off the servo is about centered between the "stops" on the servo bracket.
Snug up the bolt and nut on that torque tube bracket and then gently go move the stick right and left and be sure you have clearance and not hitting either stop and then torque the nut on the torque tube bracket.
Drill #30 hole through the bottom of the bracket and install the rivet. Good luck....it's very hard to get the rivet gun up there around the tubes, etc. to grab that rivet!! The way I got it to work was to have 1 arm of the rivet gun up above the bottom tubes and the bottom arm below. It took about 10 little squeezes to get the rivet snugged up and pulled since you can't clamp down all the way on the handles because of the tubes in between. Move the stick back and forth to one side of the other and find the place where it puts that rivet hole in the easiest way to get to.
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BELLY PAN
UPDATE: GO TO THE BOTTOM OF THIS POST AND SEE THE UPDATED DIAGRAM I ADDED. MAY, 2021
There are 2 parts to the belly pan. The first place to see where to drill the 7 holes that go through the boot cowl, forward part of the belly pan and into the fuse is first described in figure FN6 on Page 29 of the FINISH MANUAL. The 2nd part of the installation is on PAGE 287 of the FINISH MANUAL.
There are a couple of ERRORS though with this figure FN6. First, it shows the 7 screws used in the 3/32" holes to be drilled are HDW-S4R.375TA but if you go to the section on Page 287 about installing the belly pan, it calls for HDW-S6R0.5TA, which of course are larger and the correct ones.
The 2nd mistake is either where the FN6 shows to drill these 7 hole .5" from the front of that lip on the fuse OR...the mistake is the callout of the tinnerman nuts HDW-A1784-6Z-1 because these tinnerman nuts will not span 1/2" (.5") as called for because the distance from the edge of the tinnerman to the center of the hole is only 1/4"..... so, you either have to drill the holes at .25" from the edge or get different tinnerman nuts. It works OK with a 1/4" edge space, just be careful to give yourself enough room.
Use 12 of the AN5261032R8 screws with NAS1515H3L plastic washers to install the belly pan to the fuse. I almost always have to widen or move a few holes to make it line up correctly.
Drill the 2 holes that go on either side of the boot cowl that takes the HDW-S4R.25TA screws with a 3/32" bit.
Also, I would put some plastic washers on under the heads of these screws to protect the paint like we do everywhere else where we place screws onto painted surfaced.
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UPDATE: I'VE ATTACHED ABOVE A NEW DIAGRAM I GOT THAT SHOWS THE CORRECT INSTALLATION OF THE BELLY PAN WHICH SHOWS THE CHANGES I WAS TALKING ABOUT.
