HS-702 Edges, Bends, and Confusing Instructions

[StuBob]

First, I did this today on the forward HS spar, making the relief notch:

It looks like that edge is a good 1/16" too close. New part already ordered. Personally, I think it would be better to open that notch with a file rather than a Unibit, but I'm trying to follow the directions and avoid independent thinking as much as possible. If you have any relevant thoughts on this little corner, I'm interested. The other 4 corners are good. The edge distances are close, but adequate.

The other issue is the manual. Regarding the inboard ends of the HS-702 flanges, this: "Trim the inboard ends of the HS-702 flanges as shown in the HS-702 Front Spar Tab Detail. Be sure to only trim the flanges down to about halfway along the bend. Flatten the remainder of the bend."

I've read that 100 times and stared at the Front Spar Tab Detail for an hour. "Halfway along the bend" makes no sense at all, since the flange and the bend are perpendicular. And I have no idea what is meant by "Flatten the remainder of the bend." I really can't tell how much flange is supposed to come off, either.

What's really supposed to happen there? It's probably obvious and I'm missing it from staring at it too long.

Thanks in advance.

 

[wirejock]

Relief

Stuart
I think the 7 and 8 are the same if not very similar at this point.

It appears your pilot hole was too far away from the flange. The hole should be drilled 1/8" inboard of the bend line centered on the flange bend radius. Your center punched mark will land right in the bend of the flange.

I used my V-block on the drill press, to drill a pilot hole then enlarge and final drill to 1/4" using a reamer.
The hole will be 1/2 (1/8") into the flange and 1/2 (1/8") into the web. Extend the line from the edge of the hole on the flange side inboard. Cut the remaining flange away leaving the portion of flange and web where it bends into the web. This is the part that gets flattened. Flatten remaining flange material using a block of wood or sacrificial aluminum on either side so you don't damage the material and clean up relief notch with a file.

Hope that makes sense.

 

[StuBob]

Thanks. That makes sense. The relief holes/notches on the other side are somewhat inboard of that, but the edge distances are OK, so I'm probably good to go?

 

[wirejock]

Other side

Thanks. That makes sense. The relief holes/notches on the other side are somewhat inboard of that, but the edge distances are OK, so I'm probably good to go?

You may want to post a photo of the other side. There's smarter builders here than I, including a Vans employee who may be better suited to advise.

 

[StuBob]

Here are the two on the other side:

This is the bad (left) side, which I kept working on for practice, to see what other snakes might be lurking in these weeds. I think (?) I can open up the holes on the right like this. BUT, the holes don't abut the bend line, so they'd need to be filed back to it?

Ugh. When you make the same mistake four times, you've made four mistakes....

 

[ctennis]

Stuart, I'm a bit further along in the build process of my -8 but I'm located at KBAK if you need any inspiration, just drop me a note - I'm at my hangar most days.

 

[ctennis]

My HS-702 pic if it's helpful.

 

[StuBob]

Caleb, did you trim back the flange, or did your bend line happen to line up with the end of it?

 

[StuBob]

Wait! Eureka! I think. I've been looking at photos and I think I have it figured out.

When they say "flatten," they don't mean "squish," they mean "grind down!" So, you drill the holes at the bend line and grind off the flange inboard of that to where it's flush with the web.

Is that right?

 

[wirejock]

Flatten

Wait! Eureka! I think. I've been looking at photos and I think I have it figured out.

When they say "flatten," they don't mean "squish," they mean "grind down!" So, you drill the holes at the bend line and grind off the flange inboard of that to where it's flush with the web.

Is that right?

No, they actually do mean flatten. Once you have the hole, you draw a line from the outboard edge of the hole to the edge of the flange and a line from the bottom edge of the hole inboard and parallel to the edge of the flange. The area inside the two lines is the relief you cut away. It leaves a little part of the fange and the bend. You flatten this part of the flange and bend left after cutting the relief away. Once you have all the parts together you can file off any extra material.

 

[StuBob]

Thanks. When the replacement parts arrive, I'll see if I can make sense of it with the visual aids in hand.

Running Search with this part number, it appears no one else is so flummoxed by this step.

 

[StuBob]

I'll stick this in here for the benefit of future builders using Search. It turns out that Van's Service Bulletin (14-01-31) has photos and MUCH better instructions that the RV8 manual has.

So, note to my younger self: Look in the Service Bulletin. It illustrates both how and why.

 

[wirejock]

Instructions

I'll stick this in here for the benefit of future builders using Search. It turns out that Van's Service Bulletin (14-01-31) has photos and MUCH better instructions that the RV8 manual has.

So, note to my younger self: Look in the Service Bulletin. It illustrates both how and why.

Awesome. Glad you found help.
Search the SB. There's lots of good info. Also some of the builder blogs.
Some builder altered the flow of the instructions (myself included).

 

[N514CL]

I would also be careful when you cut back the angles on the top and bottom of the spar. The inboard holes that attach the skins to the spar aren't drilled yet, so you don't know if you have appropriate edge distance. I cut it conservatively just to clear the inner rib, waited until after I could put the skin on, marked the undrilled holes with a sharpie, and then filed them off.