RV-7/7a Plan Gottcha's

[wirejock]

There's a "Gotcha" on the cabin substructure. Maybe common to both Slider and tipper but for sure on the slider. I assume it is because the Firewall is common to both and the substructure is different.

Here's how it goes.
Manual says, cleko and drill F7109 Plate to F7108B Angle and F7108A Center Forward Fuselage Rib. No way to follow the manual here. It says to cleko the rib to the Firewall, but there are no holes in either. It also says to drill the F7108B Angle to F7108A Center Forward Fuse Rib, but the angle has to fit perfectly to the firewall and F601L Stiffener or the skin holes won't match the rib. The best solution is to assemble all the parts with the skin first. This pulls everything into the exact location.
First clamp the center rib forward flange to the left forward flange and duplicate the holes. Now the rib has holes for the Firewall. Cleko the ribs and subpanels but leave F7108B Angle out for now. Cleko the skin.

There's a trick to getting the skin in place. Start in the center. Work out in all directions with 100% clekos. When you get to the curve by the side skin, start at the forward #30 holes and work aft one hole at a time with 100% clekos. Leave it overnight. Back to the substructure...

Draw a 1/4" edge distance line on F7108B Angle. The Aft two holes are 3/16" so draw a line 3/8" edge distance line on the aft end for those two holes. Slide the F7108B Angle in place. Position F7108B Angle on F7108A Rib and mark one forward and one aft hole. Remove it and look at the edge distances. Adjust as needed so the holes fall within edge distance. I had to make an .063" shim between F7108B Angle and F601L Stiffener then file the slot in F7105A Rib. Once all the holes are good, clamp the angle to the rib and mark the hole through the F7108B Angle on F601L Stiffener. Disassemble. Match drill the angle and remove. Drill the hole in F601L Stiffener. Reassemble. Now all the parts are in position and the firewall can be match drilled through the rib or marked and drilled later with a super sharp drill bit. Don't mess with the hole in the top corner of the angle. Since this matches the other rib, just cleko the other rib to the forward side of the firewall, mark, remove and drill it from the front.

[amaris]

I failed to measure the exact length for the flap hinge and went by the plans. 56" was too short and doesn't allow enough edge distance. Doh.

[BillL]

I set my aileron using the tooling holes in the rib aft of spar. The ailerons were off. I went through resetting them based on in flight and matching to the flaps. Vans tech whacked my pee-pee and said in no uncertain terms to use the fixture and set to the tooling holes, not to other surfaces. So I went back to recheck and this is what I found.

The tooling holes don't all align. I would suggest you use a string or a laser level when doing this procedure and not rely on just two holes and a straight edge. It could be off.

As it turned out, it was "perfect" with the far aft and far forward holes, but as you can see some holes are not aligned.

Just be aware of this when performing the procedure.

[wirejock]

I'm going to try and point out the issues on the 7, slider as I go.
Fabricating C-668 spacers, note they all all different. Forward left, forward right, aft left and aft right. The parts are cut different left and right even though the drawing shows a pair (forward & aft). Left and right are mirror image. Label them.

Roll bar. Learned a lesson. I was trying to squeeze it to narrow the bar. When the web clamp was released the bar snapped open and actually got wider. Going to buy a come along tomorrow so I can gently release the tension.

[RV7A Flyer]

Originally Posted by BillL

As it turned out, it was "perfect" with the far aft and far forward holes, but as you can see some holes are not aligned.

Sure, because two points *define* a line...

BTW, your image shows your laser going through the wrong two holes, I believe. See DWG 12A for the ones you should be using...

[Draker]

Here's a gotcha I just learned the hard way:

When drilling the F-772B-R&L floor stiffeners to the F-772 forward bottom skin, the plans have you to draw center lines on the angle to help you align them with the pre-punched holes in the skin. This works for the two outboard stiffeners, but if you do it that way for the two inboard stiffeners you may end up with a large gap between the stiffeners and the F-601J angle that you need to attach them to:



Instead, try this:

1. Position the F-772B stiffener against the bottom skin
2. Clamp the stiffener horizontally to the F-601J angle and the F-783B cover support rib
3. Stick a sharpie through a few of the holes in the bottom skin, including the forward-most and aft-most holes
4. Remove the sitffeners and verify the holes will not bust edge distance
5. Re-clamp the stiffeners and drill

You may also have to cut a small relief notch in the top-forward part of the stiffeners in order to clear the vertical firewall angle. Here's what mine look like after using the above method:

[wirejock]

Here's one to remember.
A tiny piece, F7108C Angle on DWG 24. Don't forget to drill and install it. It ties F7105A Center Sub Panel, F7109 Plate, F7108 Forward Fuselage Rib, F7108B Angle together.
I recommend doing it with F7106 Top Skin clekoed with a few in place to make sure the holes stay in alignment.
Thankfully I caught it before the top skin was riveted in place or three rivets would have been much more difficult to remove!

[wirejock]

Not a big "Gotcha" but worth mentioning.
When the C657 Canopy Tracks get bolted in place there is a gap between the F721B Aft Canopy Deck and F757S Plate on the Aft two screws. The plabs show a spacer or shim. It's called out as a small piece but I found it much easier to fabricate a shim to span both holes. I cut a piece off a section of 1/8" angle because it already had a radius matching the Aft Deck. I just slid it in from the forward end.

[wirejock]

Don't drill the gazzillion holes in the two C791 Canopy Skirt Braces till you have the C660 Canopy Skirt and C759 Inside Canopy Skirt positioned and drilled to the WD640 Canopy Frame.
If you plan Sikaflex, you need the C759 in position or at least drilled and ready so it can be riveted and Sikaflexed. Good news is the hole pattern seems ok for C660/C759. It fit perfect.
The problem is C791 Canopy Skirt Brace has to snake around the WD640 Canopy Frame and somehow match up to the holes in C660 Canopy Skirt. Most likely it won't line up with predrilled holes. It fits better if you take a blank and get a nice fit with the WD640 Canopy Frame, drill the frame then match drill all the holes to the C660 Canopy Skirt. Then lay out the lightening holes and edge relief cuts so they are spaced correctly.
I match drilled those two pieces and spent a day cutting all the holes only to find it won't go in without major modification. Two new ones ordered.
Of course, I could be in Wonderland looking for a Yellow Brick Road. YMMV. Maybe I can actually get to the canopy someday.

[doug_rv7]

Before installing the flap actuator weldment for good, be sure to install the bolt too if you want it oriented in the direction depicted on DWG 33 View C-C (threads on the inside). There is not enough clearance between the fuselage side and weldment otherwise once the weldment is installed.

This has been discussed before:

http://www.vansairforce.com/communit...d.php?t=109140


Doug
RV-7 Finishing up!