Forced break from building, and new toys [4.0 hours]

Due to other commitments, I’ve had to take a few months off from building, from April through June, but as of July I’m back at it again. Apart from doing the MPC course there was one notable event during this time, with the arrival of the finish kit, propeller and spinner from Van’s, the cowling from Showplanes, and the engine from Barrett Precision Engines. Finish kit inventory didn’t take long. Now I’ve really got to get on with it…

  • freight1
    freight1
    Finally!!!
  • freight2
    freight2
    Unloading...
  • freight3
    freight3
    Unloading...
  • freight4
    freight4
    Unloading...
  • freight5
    freight5
    Propeller crate
  • freight6
    freight6
    Extra Alclad with finish kit
  • barrett1
    barrett1
    Barrett IO-540
  • barrett2
    barrett2
    Barrett IO-540
  • barrett3
    barrett3
    Barrett IO-540
  • prop1
    prop1
    Propeller in crate
  • prop2
    prop2
    Propeller blade
  • spinner1
    spinner1
    Hartzell spinner

 

Maintenance Procedures Training Course

In order to maintain an experimental aircraft, a builder has to complete the SAAA’s Maintenance Procedures Course. I attended the MPC course, held in Gawler SA, on May 20/21 and subsequently completed the take-home exam in June. If I pass the exam (80% required), I will get issued with a certificate, which gives me authority under CASA Instrument 15/16 to maintain this aircraft and issue new maintenance releases. The course was well run and it was good to get away and hang out with other people building their own aircraft.

TC visit #2 [5.0 hours]

In Australia, you need at least 3 SAAA Technical Counselor (TC) visits during construction in order to check off a box with the insurance company. In my case I have to fly a TC down from the mainland, so we did a combined visit between myself and an RV-9A builder in my local area. We all had a good day going over the two projects, it was good to spend some workshop time just chatting about the build(s). My TC is a wealth of information and we were able to spend some time at the end of the day going over the paperwork requirements for having a C of A issued in Australia.

Step installation [4.5 hours]

Step installation was straightforward. I started by thinking about whether I needed a drill guide (yes) and how to make one, then realized the easiest way by far would be to 3D print it. The design took 20 minutes and one print iteration. I made up guides for #30 and #12 drills. I also made up a 1/4″ guide but didn’t use it, when I decided to use the AN-3 bolt per the plans rather than the larger AN-4 bolt. The drill guides worked a treat.

Download the STL file here: Download

Step “wobbling” has been a common problem in RV-10’s. To combat this I installed a doubler plate to provide extra support for the step support block, and I used TCW Tech’s step bushings as well as carefully reaming the final hole in the step and support.

The only thing left now is to prime the steps.

  • f18b
    f18b
    Doubler plate for Delrin step support block
  • f18c
    f18c
    Step support block
  • f18a
    f18a
    Step drill guide design
  • f18d
    f18d
    Step drill guide after printing
  • f18l
    f18l
    Drill guide in position for right step
  • f18e
    f18e
    Setting the step sweep back angle
  • f18f
    f18f
    Setting the step sweep back angle
  • f18g
    f18g
    Setting the step sweep back angle
  • f18h
    f18h
    Step drilled and bolt in place
  • f18i
    f18i
    Ready to drill #30 the left step
  • f18k
    f18k
    Right step fitted, ready to remove and prime
  • f18j
    f18j
    Collect the full set!

Section 29 complete! [13.5 hours]

I installed the front floor pans and gear mounts, and have now finally completed the infamous and tediously long  Section 29 of the RV-10 manual. It was a relief to have both gear mounts bolt in without any drama, there have been some horror stories about this step in the plans. The tapered shims I made up for the gear mounts worked a treat and I all bolts were snug in their holes with no need to ream anything.

The empennage has been shoved in a back corner for the past year. I wanted to work out a few things prior to attaching the tailcone to the fuselage, so I swapped the empennage and spray booth around. There isn’t much priming left to do, so the spray booth (which is on wheels) can stay in the corner for the time being, before I retire it completely. This move has opened up the workshop a bit.

Next item is to install the steps.

  • f17a
    f17a
    Installing left floor pan
  • f17b
    f17b
    Installing left floor pan
  • f17c
    f17c
    Both floor pans installed
  • f17d
    f17d
    Both gear mounts installed
  • f17e
    f17e
    Empennage moved out of the back corner
  • f17f
    f17f
    Spray booth shoved in the back corner

 

Fuse side skins [55.0 hours]

Over the past few weeks, with some periods of non-work, I’ve de-burred, dimpled, primed and riveted on the fuselage side skins. With the exception of a few rivets I need to make up a special bucking bar for, the fuselage side skin riveting is now complete. Almost all of the riveting was a two-person operation, and “Rosie” did her usual terrific job on the rivet gun. I got well and truly tired of lying inside the fuselage twisting into all sorts of odd shapes in order to buck rivets.

I almost made a big mistake. I was all set to start riveting the right rear fuse skin, when at the last minute I noticed some holes that were not dimpled. This after having checked all the dimpling on at least three separate occasions before priming. I don’t know how I missed them, and I was lucky to notice the problem because there is no way I could have dimpled them in-place cleanly. It was a simple matter to take the skin off, dimple the offending holes, and cleco it back on.

I used a new, full sized, spray gun to prime the skins, which made me wonder why I didn’t get one sooner. Hard to believe I primed the wing skins with a mini-gun.

Side note – my son made me a replacement stainless steel shaft for the rudder pedals, after we found one of the four supplied with the kit was faulty. The new shaft fitted perfectly, so now I have rudder pedals ready to install.

  • f16a
    f16a
    Cutting out the baggage door
  • f16b
    f16b
    Cleaning up the baggage door opening
  • f16c
    f16c
    Right fuse skins, upper fuse skin, ready for priming
  • f16d
    f16d
    First use of new spray gun
  • f16e
    f16e
    Right and upper fuse skins after priming
  • f16f
    f16f
    Left fuse skins after priming
  • f16g
    f16g
    Back riveting F-1023 angle to right skin
  • f16h
    f16h
    Missing dimples - picked up just in time!
  • f16i
    f16i
    Riveted side vent
  • f16j
    f16j
    Fuse skins cleco'd in place, ready for riveting
  • f16k
    f16k
    First few rivets set, the start of fuse riveting marathon
  • f16l
    f16l
    Right rear fuse skin riveting done
  • f16m
    f16m
    Left rear fuse skin riveting done
  • f16n
    f16n
    Right fuse skins riveting (almost) complete
  • f16o
    f16o
    Left fuse skins riveting (almost) complete
  • f16p
    f16p
    Replacement rudder pedal part in place

3D printed system brackets [3.0 hours]

Under the front seats, there are four “systems brackets”, F-1084A/B, which have slots for a fuel line, brake line, and electrical wiring. In my case, there are two fuel lines, so one issue is how to deal with the return line. Another issue is the fact that s/s braided teflon lines are different in diameter than the Aluminium tubing lines that the system brackets were designed for. There is apparently enough scope to squash them in with a sliced apart grommet.

None of this sat well with me, and it was a simple matter to design a replacement upper bracket section and 3D print it in Nylon. There are two right-hand and two left-hand brackets, which have snap-in rings for two fuel lines, one brake line, and electrical wiring. Each ring has a slot for anchoring a cable tie, or waxed string tie, if needed. Each part takes about two hours to print, and bolts straight onto the standard lower systems bracket F-1084A. If in the future I need to make a change, I can simply print up new brackets and bolt them in place.

The brackets weigh 7 grams each. This replaces the metal upper section (F-1084B) and three snap bushings, which weigh a total of 9 grams, so there is no weight penalty in this change.

  • f15a
    f15a
    System bracket design
  • f15b
    f15b
    System bracket design
  • f15f
    f15f
    Part being printed
  • f15g
    f15g
    Printing complete
  • f15c
    f15c
    Parts replaced weigh 9 grams
  • f15d
    f15d
    Nylon system bracket weighs 7 grams
  • f15e
    f15e
    Plenty of stretch in Nylon support rings
  • f15h
    f15h
    Four system brackets
  • f15i
    f15i
    Bolts to standard metal parts

Section 28/29/31 marathon [71.5 hours]

Although I’ve in general followed the Van’s plans, like the wings I’ve tended to do things less incrementally. In the case of the fuselage sections 28, 29 and 31, this has resulted in a large tear down, de-burring. countersinking and dimpling activity which has occupied the last few weeks. The list of jobs to do seemed endless at times, but I finally got through it. Not a lot of pictures across this time, my bad. There was a very large pile of parts to be primed at the end of this exercise. I primed everything except the five skins (aft/forward fuse, upper forward fuse) in one marathon priming session. I then went ahead with riveting those parts I could in the fuselage structure, as well as riveting sub-assemblies together. This reduced the huge pile of parts to a manageable size.

Next job is to prime the five skins, and rivet these to the fuselage.

  • f14a
    f14a
    Countersinking F-1004K center section side plates
  • f14b
    f14b
    Installed hard-to-get-to nutplate ahead of time
  • f14c
    f14c
    Dolly cut down, mid fuselage section in place
  • f14d
    f14d
    Parts for priming
  • f14e
    f14e
    Forward fuselage assembly riveted to mid fuselage assembly
  • f14f
    f14f
    Large batch of parts for priming
  • f14g
    f14g
    Large batch of parts primed
  • f14h
    f14h
    Ready to rivet replacement front angles to F-1045 forward fuselage ribs
  • f14i
    f14i
    Replacement front flanges riveted to F-1045 ribs
  • f14j
    f14j
    F-1046, F-1013 longerons riveted in place
  • f14k
    f14k
    Forward fuselage channels, longerons riveted in place
  • f14l
    f14l
    F-1044 forward fuselage rib assembly riveted
  • f14m
    f14m
    F-1044 forward fuselage rib assembly riveted
  • f14n
    f14n
    Other misc fuse assemblies

Upper forward fuselage drama [21.5 hours]

I decided to go ahead and assemble the upper forward fuselage, since I had enough cleco’s, I needed a larger priming batch, and it gets a bunch of drilling / countersinking out of the way. It turns out there is a problem with two of the ribs in this assembly, as noted in this VAF posting, and I have the same problem. Either the holes in the front of the F-1045 ribs are incorrectly punched, or the corresponding holes in the firewall are wrong. During assembly, the ribs are first riveted to the top skin. If this is done, then the holes in the front flange will not line up with the firewall.

If the front flange holes are cleco’d to the firewall, there is a 1/8″ gap between the top flange and the top edge of the firewall. I can’t adjust the firewall flange – then the cowl would not fit. I tried cleco’ing down the top skin, and it sortof goes down OK, but the forward most cleco doesn’t actually close the gap between the flange and the top skin. The rest of the skin is “pulled down” to the flange, resulting in the skin curving inward. The front flange holes can’t be re-drilled, the correct position would overlap (just) with the existing holes.

The fix recommended by Van’s is to put a new flange on the front of the F-1045 left and right ribs. I bent up some 0.032″ Alclad to use as replacement front flanges. The pictures show the modification to the F-1045L (left side) rib. I removed the rib and made up a simple frame on the bench that the rib fitted into snugly. This allows installing and match drilling the new flange in the exact same forward position on the rib. I carefully cut the old front flange off, de-burred the resulting edge, and using the bench frame match drilled the new flange into place, finally trimming the bottom of the flange to match the front of the rib.

The rib with replacement flange can then be cleco’d back in place, with a reference line drawn on the flange so it can be sighted through the firewall holes and lined up properly. The front flange is a bit tight because the holes in the firewall are already dimpled. There are seven holes that now have to be carefully match drilled. The rib was removed again, all holes were de-burred, and the front flange holes were dimpled.

Finally, the rib was re-installed, and with the front flange holes now in the right place, the top skin sits flat on the top flange of the rib, and a straight edge held on the skin shows no gap.

With the two F-1045 ribs fixed up, the entire upper forward fuselage assembly can now be match drilled.

  • f13a
    f13a
    Front flange holes in F-1045 rib are wrong
  • f13b
    f13b
    Skin pulled down onto F-1045 flange
  • f13c
    f13c
    F-1045 rib misalignment
  • f13d
    f13d
    F-1045L rib removed from forward fuse
  • f13e
    f13e
    New angle to trim and place on front of F-1045L
  • f13f
    f13f
    F-1045L nested in blocks
  • f13g
    f13g
    Removing front flange from F-1045L
  • f13h
    f13h
    Match drilling new flange to front of F-1045L rib
  • f13i
    f13i
    Match drilling complete
  • f13j
    f13j
    New front flange on F-1045L
  • f13k
    f13k
    Ready to match drill new front flange with F-1045 re-installed
  • f13l
    f13l
    Four done, three to go
  • f13m
    f13m
    New F-1045L front flange in place
  • f13n
    f13n
    No more gap - top skin is now straight
  • f13o
    f13o
    New front flange matches firewall exactly

 

Bending fuselage side skins [13.5 hours]

The next step in section 29 of the build manual was to bend the four side skins, hit them with a mallet, twist several other structures, and fit everything together onto the fuselage. Sounds simple enough … not.

To bend the skins I made up a clamping block per the plans, finding out in the process that the blade on my ancient radial arm saw was blunt – hence all the burn marks in the pictures. It turns out you really need to apply a lot of grunt to the skins in order to produce the required conical bends. Once I stopped being timid things went better, and the aft skins went on really well. The aft skin match drilling didn’t take long either.

To bend the front skins, I bought a new saw blade and modified the clamping block in accordance with the plans. The front skins seemed a bit more difficult than the aft skins, and I wound up finishing the bends with larger pieces of clamping Aluminium than the plans called for. Both of the front skins went on well. There’s now a fairly long list of match drilling to do associated with the front skins and firewall, before I tear it all apart for de-burring, dimpling and priming.

  • f12a
    f12a
    Preparing to bend right aft side skin
  • f12b
    f12b
    Right aft side skin after bending
  • f12c
    f12c
    Right aft side skin cleco'd in place
  • f12d
    f12d
    Rear of right aft side skin
  • f12e
    f12e
    Both aft side skins fitted
  • f12f
    f12f
    After match drilling aft skins
  • f12g
    f12g
    Front structure in place
  • f12h
    f12h
    Front structure in place
  • f12i
    f12i
    Ancient radial arm saw ready to modify clamping block
  • f12j
    f12j
    Ripping the clamping block
  • f12k
    f12k
    New blade rips through hardwood better...
  • f12l
    f12l
    Rounding off the edge
  • f12m
    f12m
    Marking bend lines on right forward side skin
  • f12n
    f12n
    Ready to bend the right forward side skin
  • f12o
    f12o
    Bending the right forward side skin
  • f12p
    f12p
    Right forward side skin
  • f12q
    f12q
    Right forward side skin cleco'd in place
  • f12r
    f12r
    Left forward side skin cleco'd in place
  • f12s
    f12s
    Forward skins cleco'd in place