Archive for August, 2010

Ugh…

August 23, 2010

It was one of those days on the project today. I got the bottom skin drilled yesterday and prepped all the fuel tank stuff so I could proseal today. Everything went well up to the point of squeezing the rivets that hold the antirotation bracket in place. I ended up try to buck them but then things really went south. I messed up the shop head. So here I am about an hour into working with the sealant (you get about 90 to 120 minutes before it stiffens up—forever). I’ve got tank sealant on the bracket, the rivets, and both sides of the fuel pick up tube where it exits the cover plate. I drilled out the rivet but got shavings all over the sealant where the fuel pickup line exits the cover plate.

I now have two choices:

1. Use all the MEK I have and remove all the sealant on the various parts so I don’t have to remake them.

2. Charge ahead and figure out how to buck the rivets correctly and pick out all the metal shavings from the sealant in about 15 minutes.

The T-715 bracket is held on the cover plate with two rivets. I couldn't get a bar or a squeezer in behind the nut to make it work.

Discretion being the better part of valor, I chose the latter. I hate remaking perfectly good parts. So I scrubbed everything off and put the project away for the day so I can research the problem before making another mess out there.

Bottom Skin and Fuel Tank

August 17, 2010

Tonight I started drilling the bottom skin for the right wing. I am taking my time on this step to minimize any elongated holes. I am especially careful on the spar hole match drilling. Getting the holes to match up well on the spar was a bit challenging. After reading some similar stories online, I rigged up a stand with some shims stacked under a couple of of the leading edge ribs. This helped take some load off the ribs and spar interface and in turn helped the skin fit a tad better and avoid messing up the holes.

Also on deck tonight was opening up the fuel tank and getting an idea of how to close then out. It looks pretty straight forward— I just need to install the float unit, torque the fittings correctly, secure here and there and screw everything together. I need to research a little to make sure I am not missing anything. One area I am concerned about are the reports of nuisance leaks around fuel tank rivets. Some builders are suggesting this happening to the QB tanks because not enough sealant is being used in assembly. So I took a look around the inside of the tank and was happy to see plenty of sealant covering the flanges, shop heads and corners in the tank. I’ll look at a deeper compartment with a mirror tomorrow.

Not a great shot, but you can see the sealant is well used in the critical areas

Here's my quick solution to relieve stress on rib flanges that might cause bad fit for skin

Flying and Building

August 14, 2010

It’s rare to do both in one day. Today was great flying weather so I tagged along with fellow RV builder, Jason, in his KIS experimental for some lunch in Hoquiam and some cheap avgas in Chehalis. We also saw Jim P. in his awesome RV-7 doing a formation clinic down there. He looked very hot and concentrated heading to his debrief, so we didn’t linger too long.

Back home I got all the conduit in place. It was much more of a workout than I was expecting. Annabelle then helped me get the right wing on the table so I could get the bottom skin on to drill.

Conduit Holes the Hard Way

August 10, 2010

The QB wing comes with one 7/16″ hole for running lights, etc (A second hole on the left wing is provided for pitot line at mid-wing). I originally thought that’d be fine until I actually added it all up. Left wing will have nav/strobe wiring (5 wires), pitot and AOA lines, and pitot heat wiring. The right wing will have nav/strobe wiring and the dynon roll servo harness (5/6 wires I think) to run. I just don’t think it’ll all fit. So a little digging though VAF showed either mounting PVC or the flexi-conduit in the lightening holes using brackets or drilling a 3/4″ hole in the ribs for the flexi-conduit.

I decided on the latter because it’s lighter and, more importantly, I don’t feel like trying to replace a broken/loose bracket later on down the road. The downside is that getting those holes drilled, especially where the inboard bottom skin is already riveted, takes patience some creative problem solving.

Van’s provides a PDF on their site for locating the 3/4″ hole in the ribs. Once I marked the ribs, I drilled a #30 pilot hole through all the ribs. For the inboard wing walk ribs I used a 12″ #30 drill bit to penetrate all 4 of them at once.

Marked and punched the ribs for drilling.

Getting at the ribs through the inspection panels required a right angle attachment.

Once those were done, the fun begins. Using a #3 Unibit, I open up all the holes using a right angle drill attachment I picked up a Lowes for $18. It makes a hell of a racket so make sure the kids aren’t napping (ask me how I know).

Enlarging the pilot hole to 3/4"

I still need to finish up the wing-walk ribs with the unibit once the 12″ drill extension arrives from Avery that will take the 3/8″ shank of the unibit. Hopefully I can finish up the drilling and install the conduit tomorrow evening.

The QB Wing comes with these holes for running wires and pitot air.

Wings, Wings, Wings

August 5, 2010

Work has been picking up again so I spent the better part of the week finishing up details. The left wing gap fairing and flap brace are now installed. All the spacers and hardware were made and assembled for mounting the ailerons. Same with the bellcrank hardware. I greased and torqued the bellcrank bolts as well. I adjusted the smaller control arms relative to the wood guides mounted on the wings ends. Finally I went back to trim and bend the flap hinge pins. I have safetied them on yet as I expect to take them on and off a few more times. Now I need to assess the wire runs.