Tonight I bent, flared, and fit the Garmin pitot tube. Doing this for the second time (first time was Dynon) was a lot faster, and easier because I could use the Dynon tube bends as a reference.
There are some interesting differences in the Dynon and Garmin pitot tubes. The Dynon is noticeably longer. The tubes are marked “pitot” and “AOA” on the Dynon, but unmarked on the Garmin. I added some heatshrink labels to identify the tubes, after gently blowing through them to confirm which was which.
I’m installing the unregulated Garmin pitot tube, so there’s no controller box needed. The switch on the panel will turn it on, and it’ll stay on until switched off on the panel. This is how it works on most aircraft, and since I’ll hardly ever use it, simple seems best.
Working on the pitot tubeTubes need to be bent to allow clearance from the aileron pushrod, without contacting the spar Some thought was required to remember to put the b-nuts on at the right time: after the tube is bent, before the tubes are flared. The messy touchup paint job on the pitot mast. I could have done a better job, but I’ll worry about it later.
I’ve decided to switch back to working on the wings, so I can finish them up and then move them to a hangar. That should give me a little more room in the garage to finish the tail fairing.
It has been a couple of years since I worked on the wings, and a bit of a saga. My original quick build wings were impacted by the Vans primer problem, and I sent them back. But I had already made up the bottom skin for the left wing, including a cutout and holes for pitot mast and reinforcing. I had started riveting the skin on when the vans primer problem was announced. I carefully removed the rivets, and saved the skin. Then I decided to switch from Dynon to Garmin, which meant a new pitot tube. Unfortunately the hole pattern is slightly different and the screws are different sizes between the two. Since the Gretz pitot mast I have is no longer available for sale, I wanted to keep the original mast and bottom skin, and find a way to make it work.
On closer inspection, the holes are in almost exactly the same place. The different is the screw diameter, with Dynon using something like a 3/16 and Garmin a smaller #6-32 screw.
Because the screws carry a sheer load, and because there is plenty of material supporting the screw, I decided to use something JB Weld to fill the void under the screw heads. I coated the pitot tube mount and the screws in boe-lube and then set them into the filler. In the morning the filler had dried, and I backed the screws out, then cleaned up the filler with a file and some sand paper. I painted the filled area with some powder-coat touch up paint. The finish looks rough, but I’ll worry about it when I paint the plane, eventually.
It’s hard to reach the prop bolts with a regular crowfoot, so I bought a special prop-torque crow foot. I looked at a few options and decided on the Anti-splat Aero tool. It’s well thought out and did an excellent job. There’s a good video here that shows the tool in action.
The first step is to torque all bolts to 40 inch pounds, then to 60-70 foot pounds as the final torque. With the extension tool, I calculated 35 and 57 foot pounds. I measured the length of the arm of the torque wrench and the length of the extension and used the formula T1 = T2 * L1/L2 where T1 is the torque on the wrench, T2 is the target torque value, L1 is the arm of the torque wrench and L2 is the arm of the torque wrench plus extension.
Then final torque to 60-70 foot pounds (calculated as 57 on the tool). by holding the prop in one hand and torquing with the other I was able to torque all 6 bolts up myself.
The next step is to safety wire these bolts in pairs. That will be challenging due to the orientation of some of the bolt heads. Undoubtedly I’ll need to back some of these off to thread wire through and then re-torque.
Torque wrench extension in action.Applying final torque. One hand on the prop to prevent rotation and one hand torquing. Glad it didn’t need any more torque, else I’d have needed a second set of hands.
Tonight I finally torqued the various nuts, and installed the cotter pins, on both the throttle and mixture cables. I ended up with slightly more cushion gap than ideal, but I think that’s ok. The mid-point of the cable travel is nicely aligned with the midpoint of the arm travel on the fuel servo.
Mixture cable where it attaches to the mixture arm. This is at the midpoint of the arm’s travelThe midpoint of the throttle arm’s travel. The throttle control in the cockpit is exactly half way between open and closed in this position.
Today I tested the clearance of the prop against the spinner, by rotating the prop between full fine pitch and full coarse pitch. The clearance was good, and never closer than about 1/8th of and inch. I
followed the plans and clamped two boards to either side of the prop and rotated using the boards as leverage. Since it’s hard to twist the prop and simultaneously observe the gaps around the prop, my son Julian helped me verify everything was good by taking pictures.
With that task done, I final drilled holes for the spinner cutouts and then riveted them into place.
My contraption for rotating the prop blades To rivet the cutouts, I loosened the nuts holding the bulkhead on, removed from the studs, and rotated approximately 90 degrees to clear the prop blades.Riveting the cutouts onto the spinner bulkhead
Tonight I torqued the bolts holding the forward spinner bulkhead , and safety wired them. I re-watched the EAA Hints for Homebuilders video on safety wiring and made sure I followed the guidance. I was quite happy with how it came out… nice and tight and everything oriented correctly.
I also made a decision on an N-Number and reserved N8114X. I wanted something easy to say, but also distinct enough to hear clearly. I avoided letters and numbers with more than 2 syllables, and picked those that had one or two at most. I also wanted to incorporate “14” somehow. Since many numbers are already taken, it’s a process to find something that works. I went with 8 because it’s easy to say, is a lucky number, and my p-class number was 888. 114 was my windsurfing number, and X for experimental. Most of the time the number will be abbreviated to “one four x-ray”, which is easy to say and somewhat unique.
The forward spinner bulkhead with bolts safety wired.
Tonight I used RTV to secure the two emag blast tubes. These tubes direct air from the engine compartment onto the magnetos, helping cooling the magnetos during engine operation. I’m contemplating adding a blast tube to the alternator, but I’m concerned about moisture being blasted into the voltage regulator on the back of the alternator. This would be a problem when flying through clouds for example. The alternator is up front, but the emags are at the back of the engine. The emag blast tubes are less susceptible to moisture because of their location, so I’m not worried about them.
Right side emag blast tubesRight side emag blast tubes. Note the mess of red RTV gluing the tube downLeft side blast tubesLeft side blast tubes
Tonight I worked on securing the throttle and mixture cables. Previously I had routed the cables and loosely coupled them. I had the lever travel worked out so I had a sufficient gap at the full forward position, and at half way through the travel the levers were halfway between fully open and fully closed.
The task was to torque the various fittings which I did.
The mixture lever at the halfway point. Note the angle between the lever and the rod end bearing is close to 90 degreesThrottle lever in the halfway position.
Tonight I torqued up and safety wired the alternator belt. To help apply tension I found a steel rod, slipped a silicon cap over it, and used it to level the alternator away from the engine. This worked fine, and I was super careful not to damage anything.
It took a few goes to get enough tension to pass the slip test. This is where the nut on the alternator pulls is rotated to see how much torque is needed to slip the belt on the pulley. For a new belt it is around 11 feet pounds (the number is in the lycoming manual), and I found I was almost at the end of the tension slot to get that much tension on the belt.
Once the tension was set correctly I torqued back up the bolts and safety wired where needed.
Metal rod used to lever the alternatorAccess to lever the alternatorCorrect torque applied. Safety wired this bolt
Over the weekend I finished all of the wiring in the engine compartment, and added clamps to hold everything in position. I also modified the wiring behind the instrument panel, allowing a more direct path for the control cables, particular the prop control.
The last task remaining for engine compartment wiring is replacing the main battery wire which brings power from the battery solenoid to the V-PX. I’m upgrading from the Vans supplied #8 AWG wire to a large #6 AWG wire. I had to order new ring terminals from aircraft spruce, so I will finish that job once the terminals arrive.
