Are these good enough?

[Rynoth]

Michael, thanks so much for posting this honest video and the information that goes with it. I'm sorry that you have encountered this setback. I am now certifiably terrified of my future spar rigging experience. That seems like a very small play that wouldn't even be perceptible if the wings were actually in the spar tunnel. You've shown a lot of diligence in detecting this small error.

How does a bolt play when inserted through your wing spars outside of the fuselage? I'd think if the wing spars themselves don't show play with each other, your option #2 would be the way to go.

Edit: I've read a lot recently about pre-drilling the spar attach angles all the way up to 3/8" before the rigging process. This isn't how the plans call for it. However if such small tolerances are necessary for the spar tunnel angles, I'm really starting to reconsider the method I'll use. The more time a drill bit spends between those angles, the more elongated the holes will get. It really seems like a very delicate balance between the play in the bolts and the rigging of the wings relative to the fuselage.

Did I mention I'm starting to lose sleep at night the closer I come to this?

[rizzz]

Thanks Ryan,

The wings do not move relatively to each other when mated outside of the spar box, the issue seems to be in the forward fuselage vertical angles mostly and maybe slightly on the forward side of the forward blocks.
Installed in the spar tunnel they don’t seem to move relatively to the fuselage either, it’s only when you look very closely at the bolt poking through that forward angle you can detect slight movement when someone moves the wings up and down, and that is just not good.

The forward side is the side from where I drilled the final 1/4 to 3/8 (with that special piloted drill bit) and I believe I enlarged the most forward part of the hole just by applying the slightest side pressure every time I pushed/pulled the drill in/out.

Apart from poor execution on my behalf I think the fact that my little 2hp compressor could not keep up with the angle air drill, regularly getting blocked did not help the situation either, if I had a better compressor I would not have had to pull the drill out constantly and get a more consistent continuous push through in only a few go’s. So one lesson everybody can learn from this is if you’re rigging your wings the standard method using an air drill, make sure your compressor is up for the job, if you don’t have a descent one, rent one for the day. That is one thing I would certainly do different the next time around.

I think if I had to do it from the beginning, I would updrill the spars & blocks to 3/8 on the drill press when mating the spars, when you then rig the wings you use the 3/8 to 1/4 bushings to drill a proper pilot hole in the fuselage angles so you can still use the stecial 1/4 to 3/8 drill bit in the end to push through those angles at final size. Because you then only have to do 1/8 deep drilling just through each fuselage angle there would be a lot less room for error.

Talk about losing sleep, I’ve lost quite a bit over the last few days as well :-)

[kmacht]

Don't drill it. Use a reamer. A up-drilling it is going to just get you another oversize hole. If you use a drill bit that is 10mm you have to drill perfectly straight, have a perfectly round and centered drill chuck, and not wiggle the drill at all if you want to end up with a 10mm hole. Any tiny bit of error is just going to cause the hole to get bigger. If you can get your hands on an adjustable reamer you can sneak up on the final size and end up with a perfectly fitting bolt. That is what I ended up doing on one side of my fuselage. I up sized it to 7/16 and now have a nice snug fitting bolt after fixing a very oblong shaped hole. You can adjust the reamer a few thousandths at a time and keep trying the bolt until it fits just right.

Keith

[Rynoth]

This subject makes me wonder just how tight the tolerances are on the Onex folding mechanism where it can so easily be joined and unjoined using a quick push/pull on a lever... surely it's not much more tight than the play you're experiencing.

[rizzz]

Don't drill it. Use a reamer. A up-drilling it is going to just get you another oversize hole. If you use a drill bit that is 10mm you have to drill perfectly straight, have a perfectly round and centered drill chuck, and not wiggle the drill at all if you want to end up with a 10mm hole. Any tiny bit of error is just going to cause the hole to get bigger. If you can get your hands on an adjustable reamer you can sneak up on the final size and end up with a perfectly fitting bolt. That is what I ended up doing on one side of my fuselage. I up sized it to 7/16 and now have a nice snug fitting bolt after fixing a very oblong shaped hole. You can adjust the reamer a few thousandths at a time and keep trying the bolt until it fits just right.

Keith

Yeah sorry, when I said up-drilling I did actually mean reaming.
I don't have an adjustable reamer of that size but I do have a 10mm chucking reamer and a 10mm hand reamer as well, both very high quality and they should be able to enlarge a 0.375" hole to a 10mm (0.394") hole with ease.

Not sure what I will do yet though, ream the holes out or re-make/replace parts I'm going to have a few test runs with my reamers on some spare 1.5" bar I've got, I'll drill a few holes 3/8" and see how easily they ream out to 10mm.

[daleandee]

This subject makes me wonder just how tight the tolerances are on the Onex folding mechanism where it can so easily be joined and unjoined using a quick push/pull on a lever... surely it's not much more tight than the play you're experiencing.

Good question! I was just reading some on the OneX Yahoo Group (you don't have to be a member to read messages) about this very issue and learned quite a bit about the fact that this is a concern and some of the fixes that are being used. Here is the beginning of that thread:

https://groups.yahoo.com/neo/groups/one ... sages/2049

Dale
N319WF

[sonex892]

Micheal

If it were me I would be trying your option 2 and reaming before resorting to option 1. If 10mm isn't good enough you still have another chance left with 7/16".

Steve
Sonex 892

[radfordc]

After I bought my plane I found that the left wing tip could be moved up and down about an inch! I flew it like that for several years before finally making the fix so as least you know that however bad yours is it won't fall apart in flight.

The holes for the wing pins were badly ovaled, but the fix was easy. I drilled and reamed up to 7/16". I started by drilling in "steps" using drills that were each 1/64" bigger than the one before (25/64, 13/32, 27/64). I stopped drilling when the hole was 1/64" undersize and finished with a 7/16" reamer. I did all the drilling using a 1/2" electric hand drill and lots of WD-40 as a lube. I have to use a light hammer to get the pins to slide in now.

[rizzz]

Micheal

If it were me I would be trying your option 2 and reaming before resorting to option 1. If 10mm isn't good enough you still have another chance left with 7/16".

Steve
Sonex 892

That, would certainly be my preference if I can be sure I won’t stuff it up even further.
If I were to go to 10mm (0.394”), one other consideration is the strength of the bolts, they won’t be AN bolts at that size naturally.

The 10mm bolts I found are “metric grade 8.8” steel which means they have a min tensile strength of 830 MPa (= 120,381 PSI), at 10mm diameter they have a min single shear strength of 39 kN (= 8,768 lbs). I asked Kerry if he could verify these bolts are adequate based on the numbers provided but he says he cannot approve any alternate piece of hardware as critical as these bolts and I do have to make the calculations myself on this. Understandable.

That said,
Kerry also says Sonex themselves use trailer hitch pins instead of the AN6 bolts in their aircraft and Kerry also had those in his airplane he says, I’m sure those hitch pins do not live up to the military standards AN hardware has to either. You can actually see the pins they usein this document BTW:
https://www.sonexaircraft.com/documents ... nstall.pdf

Anyway, as someone who’s not an engineer here’s my way of determining if these bolts are adequate:
- Max weight aerobatic: 950lbs
- Max load: 6G
Now, assuming the whole weight of the airplane hangs (which probably isn’t the case) that means we can have a maximum of 5700lbs hanging from those 2 bolts. That is already well below the min single shear of a single bolts, and in this case the load is hanging from 2 bolts. I’m not sure if I can just divide that 5700lbs by 2 to determine the load on a single bolt but given I’m already well under it probably doesn’t matter anyway.

Anybody here with some more knowledge in these matters want to comment on my calculations?

[rizzz]

Ok, just to keep you all up to date on what I’m doing about my issues here.

After a lot of going back and forth on this, I've decided to just remake my forward attach blocks and forward fuselage angles. It’s a bit more time and effort but I feel more comfortable with this decision.

I know reaming out the holes to a larger size might be the easiest and fastest solution but I just can’t bring myself to enlarge the holes on the aft spars/blocks/angles/fuselage verticals since those are all good, the 3/8 bolt sits very snug in those so I'm not willing to risk destroying those as well even though the risk of doing that might be small.

Even the aft part of the forward blocks appear to be OK, the enlargement of the hole seems to be max 1/2" deep in the blocks if it’s even that. It's hard to say exactly how deep but it is clear the bolt is nice and snug on the aft side of the forward blocks as well and the angles the blocks are attached to are certainly not affected.

So I’m thinking about re-using the spar angles the blocks attach to, attaching new blocks to them and use the existing 3/8” hole in the angles as a guide to drill the holes through the blocks from the back on my drill press, probably using a 3/8” – 1/4” bushing in the angle to drill a pilot hole first.
I would then only have to put the wings back into the fuselage and drill the 3/8” through the forward fuselage angle from the aft side this time, possibly using a 3/8” – 1/4” again bushing to drill a pilot hole first here as well. Little risk of screwing that up (again).