Joshua’s RV-9A Project

This was the big day.  Allison was back in the shop, and we started the fun by re-setting the outboard floor stiffeners from yesterday, then completed the inboard stiffeners.  Riveted the aft row of rivets at the firewall (the forward row doesn’t get installed until cowling work).  There’s a few tricky ones in there: the outboard few where the firewall weldment is very nearby, and the couple which are almost under the inboard angle brackets where the engine mount bolts on.  With a few different bucking bars (including a big crowbar), we made it work.

While Allison took a break, I squeezed the longeron rivets that do not attach any top skins, leaving a patten of holes open on the left side for the clips that will retain the static air tubing.  Next, I climbed under the fuselage and riveted the aft baggage-rib-to-bulkhead rivets.

After that was done, it was on to the tailcone join, which went quite quickly, just a couple rows of rivets, and up the side of the conical bend area.

With all the riveting done, there was nothing left to do but take the plane through its first (and only) aileron roll…  (can you do an aileron roll with no ailerons?)  The canoe is flipped!  Total build time to this point: 745.1 hours.  Now the real fun begins!

Riveted the baggage wall ribs to the side skins, and the double row of rivets at the tailcone join, up as far as I could reach.  All the remaining riveting will require a second pair of hands, as my arm-length is maxed out.  After the riveting I could do was done, I putzed around looking at things on the fuselage and in the plans, shaping the picture in my head of how the next set of parts goes together.

Progress is being made on the fuselage riveting…I first set the two remaining rivets on the inboard floor stiffeners, then clecoed in the armrests and baggage side wall ribs.  The lower longerons were bolted to the firewall weldments; torqued, sealed, and the bottom floor skin clecoed in place, followed by the outboard floor stiffeners.

With all the components now clecoed together, there’s nothing left to do but rivet!  Working from a stepstool as a seat, I was able to reach about 2/3rds of the way up the side walls, and completed everything I could reach back to the 705 bulkhead, along with all the longerons and bulkheads aft of the 706.  I should be able to get most of the baggage walls and 705/706 bulkhead-skin rivets in a similar manner.  I was also able to reach about half the rivets joining the side skin to the outboard seat ribs, by reaching through the aileron pushrod holes.

Finished up a couple odds ‘n’ ends, and started the fuselage riveting tonight.  I had read that the rivet immediately above the rear spar bars can interfere with the rear spar stub on the wing, so I dimpled that location for a flush rivet.  Also pre-riveted the center section doublers to the side skins as called for (though the plans call out 5 and 6 rivets, I believe they mean 6 and 7; Smitty came to the same conclusion.)  Riveted the angled side ribs to the skin on all rivets that aren’t shared with the side skin; this required temporarily removing the bolt from the rear spar to gain access to the rivet tail.

With those preparatory steps out of the way, it was time to marry the tailcone and center fuselage for the final time.  Once the double row of holes on the bottom was clecoed, I added the longerons and clecoed up to the 904 bulkhead, then added the side skins and clecoed those in place.  Firewall is added next–the angles clips and side stiffeners must be riveted to the firewall at this point if not already done, as access is limited once the side skins go on.

After the firewall was in place, I added all the structural pieces between the 904 and the firewall.  Squeezed the accessible rivets on the inboard floor stiffeners in preparation for adding the forward bottom skin.  Shortly after that, I squeezed my left pinkie finger, so it was time to call it a night.  The aftmost rivets on the floor stiffeners will need to be set with the gun, as they’re tucked too far under a flange to get at with the squeezer.

With the install of the crotch strap brackets today, the fuselage is nearly ready for riveting.  Before the brackets could be fit, I riveted the two seat ribs to the bottom skin and vacuumed all the metal chips out of the center section.  After deburring them to prevent scratching up the ribs, the brackets were then fit in place, with spacers clamped between the fore & aft brackets to provide proper spacing.  The angle drill extension allowed me to get in there and drill — this cheapo extension feels like it may be dying inside, so hopefully it’ll hang on to life for a bit yet.  I would be tempted to replace it with a real angle drill with a small head, as the wider body on this one sometimes results in slightly angled drilling.

With the brackets removed, and holes deburred, I vacuumed the center section once more, etched and primed the brackets.  Discovered that the Stewart Systems primer is too thick for the Preval sprayers, so I’ll have to try it thinned down a bit…for now, I just loaded up the gun and shot with that.  After the primer had set (sped up by setting them under the infrared heater, which has been a godsend for cold-weather priming), I clecoed them in place and pulled the 40 blind rivets that hold them in.

Clecoed the angled side ribs to the bottom skin in preparation for riveting, along with the forward tab that connects the rib to the 705 bulkhead.  Need to remember to revisit one rivet location near the rear spar on the side skins, that others report really should be a flush rivet to prevent interference with the rear spars later on.  After the angled ribs are riveted on, the tailcone can be attached again and riveting can commence.

Heard back from Van’s on Tuesday about the seat pan ribs — Joe said it was alright to have the elongated holes, just use a nut and washer.  I’ll be more careful, next time, really!  (Browsing his build log for an unrelated topic, I saw that Chad Jensen actually made the same mistake; he fixed it by a different method–widening the crotch strap brackets–which would have been easier, had I any suitable scrap sheet…)

So tonight, after buying some paint supplies at Menard’s, I shot interior color on the side skins and longerons.  The paint goes on pretty nice with the gun (thinned 8oz/quart with xylol); I think it’s even easier to get an even finish than with the rattle cans, though of course the rattle cans are easier to deal with, esp. for small parts.  Also shot a scrap piece with some tan textured paint we picked up to try for the rudder pedals…I’ll give the test piece to my interior designer (hi, Allison…) for evaluation.

After the joy of painting ended, I squeezed nutplates onto the various uprights and stiffeners that receive them, and did some other riveting: the gear attach webs, spacers, and tank attach angles; that whole assembly to the side bulkhead uprights, the little angle “clips” to the side stiffeners, and the lower longeron gussets to the firewall side angles.  Touched up primer in a couple spots that needed it on some of the pieces.

Lastly, I addressed the center section: clecoed the two now-correctly-placed ribs in place and drilled the 3/16″ holes, then removed for deburring, spot primed where needed, and re-clecoed in place.  Once they were fit, I riveted their fore and aft ends to the bulkheads.  One hole in the lower rear spar got a little messed up in the drilling out earlier, and rivets kept clinching over; that one ended up with a short AN3 bolt (always a defeating moment, but probably the best thing to do…and no one will ever see it down there anyway).

Tomorrow, I hope to finish re-riveting those two ribs (easy), and start putting the fuselage back together for final riveting.

Etched all the fuselage components that are done to date, except for the side and forward bottom skins, and the main longerons.  Those are big enough that they really need to be done outside (the etch solution eats the concrete floor, and they’re too big to fit in the big plastic tray I use for etching parts); we’ll see if the weather is good enough tomorrow to get it done.  Should be able to get the priming done this week.

After tiring of etching, I thought I’d look at the install of the crotch strap brackets.  This is where I discovered a dormant screw-up that I was previously unaware of.  Turns out that when I initially fit the seat ribs to the center section, I got the inboard pair of F-916 ribs reversed.  That is, the inboard F-916-L goes on the right side, and vice versa.  Unlike some other parts of the plane, it’s completely possible to reverse these with no ill effects–the seat pans, bottom skin, and everything else all fit perfectly, so nothing screamed “wrong!”  Until I held the crotch strap brackets in place, when it became very evident what had happened.  The space between the ribs that are spanned by the bracket is about 3/4 of an inch too wide.  Since the center section isn’t yet attached to the tailcone, access to drill out and re-rivet these ribs isn’t a problem, so I drilled both out and put them in the correct orientation.  Easy enough, except for one thing: the 3/16″ holes that were match-drilled from the main spar, where AN3 bolts are inserted, are not in alignment with the line of rivets that runs down the forward flange of the ribs, but rather offset by a small amount.  This means that when the already-drilled ribs were flipped into the correct orientation, those 3/16″ holes are out of alignment by about 1/2-diameter, which would result in ovalled holes if drilled.  I’ve sent an email off to Van’s asking their advice–my guess is that they’ll say it’s fine, put in the bolt and move on, since that rib is also held in by a bunch of rivets.  But better to ask…if the ribs need replacing, it should be easy to do that, too…for $17.73 apiece, plus shipping.  Sigh.  I feel like I’ve made several stupid mistakes lately.

(The ribs in question are the third in from each side on the drawing — the inboard “F-916-L/R outboard seat rib”.  Marked by the clecos on the second photo.)

Much drilling today.  Began by drilling the armrests and removing them, and trimming the 623 bottom skin corner ribs to clear the step tubes.  Next, pulled the side skins to do the conical bends where they meet with the center bottom skin and tailcone, and reinstalled on the fuselage.  The bending was pretty easy, and in fact, I will have to un-bend the left side just a bit later, as it’s a bit concave just above the bend.  The right side turned out perfectly.

The next step is drilling the main longerons, and that is indeed a lot of holes.  I worked from aft to fore with clamps and drill, doing every fifth hole on both side, then filling in with the third hole, then going back and drilling all the even-numbered holes.  Now, the longerons are drilled up to the 904 bulkhead.

After the longerons were drilled, I drilled the bottom and side skins to the skeleton, and to each other.

Started out the weekend by drilling the baggage & seat floors to the skeleton and making sure everything was clecoed solidly in place.  Also, filed the slots in the tailcone bulkheads wider, so that the longeron angle would fit — the slots are too narrow as they come from the factory.  Fortunately, this issue is well-documented on other builders’ sites, so it’s easy to be prepared.

Next step is to prep the longerons for the big join: trimming the excess length from the aft ends, cutting the necessary relief into the aft end, and slotting them for the HS attach bars.  Once prepared, they get placed in the tailcone and clamped in place at the appropriate location.

Then, it’s time to set the center fuselage in front of the tailcone, and let the two become one.  The actual join can be a bit tricky, as the tabs of the baggage ribs like to get hung up on the 706 bulkhead.  This is easily resolved by partially un-clecoing the baggage floors (in my case, I had only to open up the left side) enough to reach in and apply some coaxing to the tabs.  Once the tabs were aligned, it slid right into place, and a row of clecoes across the bottom secured it.

Adding the forward side skins is next, but first, the step hole must be drilled…this is where trouble strikes.  Grabbing the hole saw marked for 1 1/2″, I drilled a hole.  Hmm, looks a little big, I thought–turns out I had grabbed the 2″ saw, which was also marked “for 1 1/2′ pipe clearance.”  Oops.  Try the step–of course there’s a big gaping hole underneath…The skin is nearly $100 to replace, plus s/h, so I will inquire as to whether a suitable doubler could be employed here, since the larger hole (it’s only 1/4″ bigger all the way around) is mostly hidden by the step’s mounting flange, anyway.  Any spot on the bottom where the oversize hole & doubler might be visible coule probably be filled with something later, before paint.  Moving on, I drilled the other skin with the proper size saw, filed some extra off to allow the mount plate to site flat (the weld on the step increases it’s diameter), and attached both sides to the now-lengthy fuselage.

Finally, fluted the armrests and clecoed them in place.

Completed riveting the bottom skin to the center fuselage with Allison’s help; easy as pie.  Proceeded to flip the assembly right-side-up and attach the forward half of the 904 bulkhead, then cleco in the baggage and seat skins.  The baggage skins gave me some pause, as they didn’t want to fully align with the 905 bulkhead…starting from the center and working out solved the issue; there is a curve formed at the aft edge of the center fuselage, to match the forward bulkhead in the tailcone.  The bottom skin wants to pull the curve flat until the baggage skins are in place.

We should see the first iteration of the center-to-tailcone join this weekend.