SonexBuilders.net

Hi all

I am looking at plans page SNX-F02, specifically section C-C where SNX-F03-06R/L (right and left hand attach fittings) get mounted.

Using the matched hole kit with pre made angles, these fittings have no pilot holes for the rear spar attachment. The rest of the rear spar carry through assembly does....

So I am pondering how to drill the attach fittings when the other parts all have 3/16" holes in them....especially if it is installed in the fuselage....

At this point I am thinking to install the rear spar carry through assembly. Clamp these attachment fittings in place, then remove the assembly and use the drill press.

The attachment fittings have pre drilled holes for the fuselage mounting but the fuselage does not have pre drilled holes so this should work.

I am curious if anyone else has encountered this.....


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

I believe I found an answer to my own question by reading the assembly order steps more slowly. (I am a few weeks away from doing this)

It says to cleco the angle in place then drill....

Still interested in hearing if anyone has done this with matched holes and encountered any challenges.

Thanks and blue skies


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

Hi Robbie

The 1 x 1/4" and 3 x 1/8" holes per side in SNX-03-06 are drilled to the rear carry through spar SNX-F03-01 during wing rigging, Not before! The carry through spar must be able to float to allow adjustment whilst setting up the wing rigging dimensions. This determines the hole locations.

This may explain why there are no matched holes.

Steve 892

Thanks Steve!


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

Hi Robbie,
I don't have the match drilled parts. I followed the assembly instructions step by step. The only problem I had was that the plans called for drilling the holes for the attach bolt on the rear spar carry through to 1/4". While the plans for the wing rear spars only drilled the hole to 3/16th. So I had to up drill the wing rear spar holes to 1/4' when I was rigging the wings (Rear Spar Carry Through Installation).
I don't know if it will be any help to you but in my log here is what I did - http://stewartaircraft.net/log.php?sub=F02
Again I do not have the match drilled parts.
In my wing rigging I only had one big problem. I had the forward part of the hole for my right wing main spar not follow the pilot hole. So I had to re-due the forward attach block and forward vertical angle on the right side. But in the end it all turned out good. I think I got in too big a hurry to get that hole done.
My suggestion is to go slow and follow the assembly instructions.

John Stewart
Sonex 1462

Thanks John. Looked it over and bookmarked it.


Robbie Culver
Sonex 1517
Chicagoland
Tails and Wings complete - finishing fuselage.
N1517S reserved

An old subject line revisited...
I'm at this point now, where I'll be rigging the wings. Reading over the general construction order, step #12 it says to "push end of 1/4" pins flush with forward side of Rear Spar Carry Through Channel when locating Attach Fittings" (this is SNX-F03-06R & L).

This would mean that you have previously up drilled the 3/16" holes in the rear spar and all the parts at each end of the Rear Spar Carry Through Channel, where the 1/4" bolt will be eventually inserted. This is the bolt that sets your wing incidence.

HOWEVER, step #15 says to back drill the 3/16" through the Attach Fittings and pin temporarily with 3/16", then drill 1/4" through assembly. The confusion arises because there is no 3/16" hole if you were able to push a 1/4" pin "flush with the forward side if the Rear Spar Carry Through Channel".

I'm thinking this was written for kits WITHOUT the pre machined parts (I have the premachined parts).
The kit parts F03-02, 03, -04, -05, -06 make up the assembly for the 1/4" bolt which sets the wing incidence. F03-03 FITTING, is the only part which has a 3/16 hole. All the other parts involved EXCEPT THE ATTACH FITTINGS F03-06R &L, already have a 1/4" hole in them from the factory.

I think the logical step is to accurately line up F03-02, 03, 05 using the prepunched pilot holes and drill the 1/4" hole, done on the drill press, not in the fuselage. Then up drill the 3/16" hole in the rear spar to 1/4". Then when installing the rear spar carry through, I'll be able to insert a 1/4" pin as stated in
step 12 and proceed to locate the final part F03-06R &L, the Attach Fittings.

I hope I've been clear enough that someone will understand what I've tried to explain and say "yes, sounds good, that's what I did!" If not, sorry for giving you a headache.

Picture to follow...

This is doing my head in too, I emailed Sonex support on this and they said they can't recommend pre drilling any of these parts and never offered any suggestions on how to do this. Hopefully a few people can advise how they have successfully done this. I have the B model and the rear spars only have 3/32" pilot holes as does the forward side of the spar carry through. The instructions on the plan sheet certainly can't be followed without deviating from them. Yes I have a headache from this....

Hi Darick,

I just got another response from Sonex which should clear up the process. I'll put the questions I sent Sonex support first to give you a reference on which steps are being answered. This is for the B model but should work on other models too but the step numbers could be different in the plans.

Here's my email to sonex:
There are a few steps in the instructions for wing rigging that don’t make sense to me, wondering if you could shed some light on how Sonex has gone about rigging the rear spar.

The steps that have me baffled are as follows:

In step 10 it states: 'Pin rear spar carry through assembly to rear wing spars using 1/4” diameter pins. Install from back to front temporarily’ (At this stage this isn’t possible as there is only a 3/32" pilot hole in the spars and also the forward side of the rear spar carry through).

In step 23 it states in a Note: 'Push end of 1/4” pins flush with FWD side of rear spar carry through channel when locating attach fittings’ ( Still the holes would only be 3/32” pilot holes as above)

In step 26 it states ‘Cleco attach fittings to rear spar carry through assembly & back drill 3/16” holes through attach fittings ( be careful not to enlarge holes in rear spar carry through assembly) Pin temporarily with 3/16” (this too seems to contradict previous steps as now it seems these holes should be 3/16” and not to enlarge the holes in the rear spar carry through assembly)

Step 27 has the assembly up drilled to 1/4” which would need to happen sometime before step 10 but then that would contradict step 26 being still at 3/16”

Here's the response from Sonex:
Hi Murray,

Sorry for the confusion:

1. Drill the hole in each rear spar attach plate to 3/16”.

2. Drill aft spar pin mating holes in the rear spar carry-through to 3/16”.

3. Use a 3/16” pin for step 10.

4. For step 26 back drill to 3/16” so all the parts that receive a 3/16” diameter pin to hold the rear spar are now 3/16” diameter.

5. Step 27 you up-drill the parts to 1/4”


Hope this helps