12 things I wish I would have known: by Paul LaRue

[sonex1374]

This post originated in another message thread (viewtopic.php?f=21&t=5585#p42382), but is reproduced here to make Paul's excellent information easy to find.

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12 things I wish I would have known:

1. or realized how difficult it is to work under/behind the panel. Although I made the center of my panel removable like Jeff did, I don' use that panel because it's just not big enough. I'd perhaps make my entire panel hinge down.

2. In addition to the first item, I would have ran a channel for all, or most of the panel wiring on the passenger side even if I had to add a few rivets in the fuselage to support it. Yes the wires would be longer, but they would have good support instead of just being zip tied to the fuel tank straps.

3. I would have enlarge the full flap slot so the flap handle wouldn't get jammed. This part was fabricated by Sonex, and caused me to have to fly about 20 miles with full flaps.

4. I would definitely still use the red cube fuel flow sensor. It really helped with the initial WOT tuning of the engine. I also use it and EGTs to determine % engine power level during cruise.

5. I would have drilled the wing attach blocks to the final size on a drill press while the spars are clamped together. I used a step drill with the competed wings clamped together outside the fuselage, and this also worked well, but required a special step drill. I think the whole thing could be done without a step drill if drill bushings were used when finally drilling the verticals as I did.

6. The screw that holds the wheel pant to the axle bottomed out, so there wasn't clamping force. This and a very poor landing resulted in the wheelpant catching on the tire, and almost causing me to nose over. I've since reinforced that area, and used washers as needed.

7. Controversial one is using loctite to hole the titanium legs in the axle sleeve, and the engine mount. Kerry had suggested I not do it, as removing them would be very difficult. I spent a lot of effort making sure that the holes I drilled were a nice snug fit on the 1/4" bolts. The axle sleeves still began to oval after a while. I ended up changing to a 5/16 bolt, and used leftover green loctite 629 (from Jab prop hub bolts) on both ends. I figure if I ever have to remove them, it's be because something major happened anyway. I'd remove the engine mount from the plane, and heat the loctite until the legs came loose.

8. I would have used the resistive spark plugs from the beginning. They cut down on electrical noise tremendously.

9. I wish I wouldn't have spent time making a heat muff for the exhaust pipe for cabin heat. Getting warm air from the oil cooler works just fine, and there is less risk of CO poisoning.

10. Speaking of CO. I with I would have know I was going to gave such an issue with it. I've made sealing modifications to the firewall, including the fuel fill area. I beaded my exhaust slip fit joint, then even brazed it (but couldn't get it brazed in the middle so it still leaked). In the end, sealing the firewall/fuel fill area, the tail area, and clamping an extension to only the front of the exhaust pipe to create a low pressure area (to "pull" out the exhaust) is what it took to solve the problem.

11. Occasionally when I'm descending with an almost full tank, I'll start to smell fuel. I'm thinking it's leaking out the fuel vent. Most of the time it's not an issue, but occasionally it can be really annoying. maybe someone has the solution to this.

12. When positioning the horizonal stabilizer to the fuselage, make sure that the elevator control horn isn't going to contact the vertical stabilizer. I measured mine several times, and I think the holes on my horizontal stabilizer were already drilled by Sonex. I wanted to make sure there was enough hole to edge distance for the bolt holes, so my horizontal stabilizer ended up being about 1/8" too far back. I ended up having to do a lot of grinding on the elevator control horn to keep it from rubbing. Don't make this mistake, clamp it all on first and verify before drilling.


Paul LaRue
Sonex N454EE Plans# 1509
Jabiru 3300
First Flight 12/21/2017
http://www.mykitlog.com/lpaaruule

[GraemeSmith]

11. Occasionally when I'm descending with an almost full tank, I'll start to smell fuel. I'm thinking it's leaking out the fuel vent. Most of the time it's not an issue, but occasionally it can be really annoying. maybe someone has the solution to this.

And with a vent turned through 180 and brought down the firewall to exit at the bottom of the aircraft - when I picked the tail up with a full tank it would start a syphon which would waste a gallon of fuel till I got to the cap and opened it to break the siphon action. And so I could be pretty sure that in a dive I was probably throwing fuel away too - as you report.

I fitted a small check valve in the vent line to let air in and stop fuel going out. Peter Anson makes one - half way down this page:

http://www.ansoneng.com/sample-page/pro ... tem-parts/

But you can find plenty of the right thing locally.

[pfhoeycfi]

I wish I had known just how compressed the leading edges were in their shipping box. When I opened the box, the edges sprung open pretty violently, creasing both badly...both were ruined.

[trwolf]

Regarding your number 11 concerning fuel smell. You may have already fixed it, but if not. I also was getting some fuel oder, and it turned out to be fumes from my fuel vent (bottom of the cowl) wafting up trough a void that I believe was left in the fuselage where it joins with the engine mount and gear legs. I used rtv to seal the seam and no more fumes.