One Rivet At A Time

Welcome to Kevin Horton's RV-8 Project
Tuesday, March 03 2015 @ 07:04 PM EST

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Pitot Tube Connection

Finishing Kit

I attacked the pitot tube line connection at the pitot tube this week. I originally had a fairly complicated plan that I had borrowed from another builder web site, with many different fittings required to make the transition from the pitot tube to the nylon pitot line. Then, when I pulled out my tray of #4 plumbing fittings, I spied a fitting that I had forgotten I had, and I realized that it would allow me a much simpler transition.

I'm using a pitot tube mount I purchased from Warren Gretz at Gretz Aero. The pitot line connection on the pitot tube will end up inside the pitot tube mount, so it needs a short piece of aluminum line with flared fittings on each end to allow a connection in the clear above the pitot tube mount.

I connected an AN822-4D elbow at the top of that short piece of aluminum line, with the pipe thread on the AN822 screwed into a 266-N female Nylo-Seal connector. The nylon Nylo-Seal pitot line will connect to the 266-N connector.

I managed to drop the pitot tube, and broke the brown (Bakelite?) electrical connector. I glued it back together with 5 minute epoxy, and an aluminum reinforcement. But, now I am concerned that the high temperature from the pitot heat will soften the epoxy. So, I'll purchase a new connector. So far, the only place I have found that sells them is Aircraft Spruce, and that little connector costs $58. Drat.

Tonight I also completed two more little things on the big To Do List, but I found two more that I needed to add - net change one item.

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Windscreen Fairing Installed

Finishing Kit

I got a few small items done this week, and two larger items.

I spent several hours finishing off the sound and heat insulation on the firewall. The hardest part of that job was removing the adhesive from the industrial grade stick-on Velcro that I had used on the first aborted attempt at installing firewall insulation. I was able to use most of the original Velcro on the firewall, but there were several pieces that turned out to be poorly placed, so I had to remove them. I had been worried that the adhesive wouldn't stick well to stainless steel, but that turned out to not be a problem. I was able to peel the Velcro off, with considerable effort, but there was a thick layer of adhesive left behind. I finally discovered a wax and grease remover that would soften it slightly, so I could remove a few microns at a time with a scraper.

I had a minor disaster while installing the firewall insulation. The piece that goes at the top right is shaped so the inside edge of the forward baggage bay door just clears it. After I installed it, I decided to close the door to confirm that the insulation wasn't interfering with hit. The door seemed be hitting something at the front edge, which I assumed must be the insulation, so I gave it a rap with my hand. There was a loud SNAP, and the door closed. Oh oh. That didn't sound good. It had been a long time since I had closed the baggage door, and I had forgotten that it has a slight twist in it. You have to twist it a bit as you close it, or the forward edge hits the UHMW plastic block that the forward latch rod goes into. The edge of the plastic snap ring had hit the edge of that block, which is why the door didn't want to close, and the snap ring broke when I gave the door a rap with my hand.

To further complicate things, for some strange reason, the short screw that fastens the latch rod arm on the back of door lock had come out, and the latch rod arm had come off, which allowed the forward latch rod to slip inside the door. I had actually seen that the screw was missing a week ago, but I hadn't comprehended what I had seen until just now. It is weird that it took my brain a week to process what my eyes had seen.

The latch mechanism was designed to be assembled before the inside skin of the door was pop riveted in place. Now I had to repeat this on an already assembled door. Fortunately, I had a spare screw for the lock, and this time I put some Lock Tight on it. It took quite a bit of fiddling around, but I was able to get the latch assembly reinstalled.

Yesterday I cleaned the windscreen, as it had some residue from the 3M 471 vinyl tape that I had put on it when I built the fibreglas windscreen fairing. Today I installed the windscreen, scuffed the aluminum that would underlay the fairing, and cleaned and scuffed the inside surface of the fairing. Then I gritted my teeth and put a 3/16" bead of Lexel adhesive where the fairing would go, and popped it in place. I used some 3M 471 tape to secure it in place.

I was very worried how it would turn out, as a major problem would probably require me to buy a new canopy to make a new windscreen, and make a new fairing. This would be a major, major setback. I was very nervous when I installed the fairing, but it looks perfect. Whew. There is very little gap between the fairing and the windscreen or fuselage, and the fit is perfect. I'll give it a couple of weeks to fully cure, then I'll track down some auto body seam filler to seal the small gaps between the fairing and the fuselage and windscreen.

The RV-8 instructions would have the builder lay up the windscreen fairing in place, and never remove it. I was worried about how I would get a nice edge on the fairing without scratching up the windscreen with the sanding. I borrowed my approach from John Huft - he had the idea of laying the fairing up on tape, and removing it for sanding, then bonding it on later

Note: John Huft used Lexel to bond the fairing to the Plexiglas, and fibreglas resin to bond it to the aluminum. The Lexel application info seemed to indicate that it might not have quite as strong a bond to aluminum as it would to Plexiglas and fibreglas, so I decided to do a test. I cleaned and scuffed up pieces of fibreglas and aluminum, then bonded them together with Lexel. I checked the joint 18 hours later, and the bond seemed to be very weak. I decided that I would have to use fibreglas resin. But yesterday I took another look at this joint. It had been about about three weeks since I had bonded the pieces together, and now the bond was very, very strong. The bonded area was only 1.25 square inches, but I could not pull them apart, even though I had moved the bond 18 hours after it had been made. Lexel appears to make very strong bonds, but it takes a long time to fully set up.

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Brake Lines 2

Finishing Kit

I had really expected to get a lot of work done during the week last week, but four of the evenings had some major unexpected event that disrupted RV-8 work.

I was able to finish off the installation of the Teflon brake lines at the bottom end of the landing gear legs. The space inside the landing gear fairing reduces as you move aft of the landing gear leg, so I had to grind off most of the hex in the middle of the AN919 fitting that joins the aluminum line to the flexible hose.

The aluminum line, fitting and flexible hose are secured to the landing gear leg, with sections of tough plastic line between the tape and the landing gear leg. I've used vinyl tape for the moment, but I'll replace that will something more durable.


I also removed the prop so I could change the alternator belt. Originally I had installed a converted automotive alternator, but I later decided to replace that with a B&C Specialties alternator, which needed a different belt. I had been putting off doing this task, as I didn't have a ready way to support the prop while I removed it and reinstalled. I could borrow the engine hoist that I used the first time, but the hoist owner has moved well outside Ottawa, so it would have take at least two hours to obtain the hoist, and another two hours to return it. But Jim, a coworker, and his son, offered to lend a hand. They supported the prop while I removed and reinstalled it. Yesterday I torqued the prop bolts, but I still have to safety wire them.

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Brake Lines

Finishing Kit

I've been on the road essentially non-stop since Friday the 15th. Terry and I went to the Niagara wine region from the 15th to the 18th, and I was in Phoenix from the 20th to the 23rd.

Today I got a small amount of work done on the brake lines. A while back I managed to hit the aluminum brake line that runs down the back of the left landing gear leg. The impact was hard enough to put a bit indentation in the brake line. I decided to take advantage of this screw up by replacing the bottom section of the brake lines with sections of #3 metal-braided Teflon hose. The pre-made #3 lines and the fittings came from Pegasus Auto Racing.

I got this task about two thirds complete. And I discovered one more item to add to the big To Do List, so net progress was minus one third of an item.

I should be in town for the next week, so hopefully I can make some progress.

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Very Misc Progress

Finishing Kit

I was in Lawrence, KS all week, only getting home very late Friday evening. Yesterday I had a bunch of stuff that needed doing around the house, and today Terry and I spent most of the day just enjoying the wonderful weather. So very little progress was made this week.

While I was in Lawrence, I went to Topeka to attend a local EAA chapter visit to Eric Kerns RV-8 project. Eric is moving much faster than I am, and has a very nice looking aircraft that is well into the finishing stage.

I picked up two tubes of Lexel adhesive in Lawrence (I couldn't find a local distributor), as it is reported to be a good choice to bond the windshield fairing to the windscreen. I'm not sure whether I will also use it to bond between the fairing and the fuselage, or whether I should use epoxy resin. Yesterday I used the Lexel to do a test bond between a piece of fibreglas and a piece of aluminum. I'll give it a week to cure then see how strong it is.

Today I put the windscreen back on temporarily, then marked the outline of the windscreen fairing. I sanded the portion of the windscreen that will bond to the windscreen fairing, to give a better surface for the adhesive to bond too. I also attempted to wash the windscreen, using soap and water. That didn't get it really clean - there is still some sort of residue from the 3M 471 vinyl tape. I need to find a proper Plexiglas cleaner.

This evening I installed the sniffle valve in the bottom of the engine's induction tract, and fabricated a piece of aluminum tubing to act as a drain. I used a short length of automotive fuel line to act as a transition between the sniffle valve and the aluminum tube. I need to get some small hose clamps to finish this off.

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Misc Progress, Updated To Do List

Finishing Kit

Today I polished out the scratches on the windscreen, as I figured it would be easier to do before I permanently installed it. I used the Scratch Off Optica 4 kit, sold by Van's. It does a very nice job. Now I just need to acquire some Lexel adhesive, and I can install the windscreen and the windscreen fairing. I can't find a local distributor, but I will be in the US next week and I hope to find some at a hardware store.

Some needed hardware arrived earlier in the week, so I was able to finish replacing the plastic low pressure brake lines with Teflon tubing.

I've slowly ground down the To Do List - now it has about 33 items before going to the airport, and a bunch of those can be done once I receive some more Teflon tubing and fittings I ordered from Pegasus Auto Racing Supplies - they carry a good selection of Teflon tubing, including premade tube assemblies of various lengths. I intend to put a length of flexible Teflon tube at the bottom of each landing gear leg to connect up the brake lines to the brake calipers. I managed to damage one of the aluminum brake lines, so I either need to replace the whole thing, or cut off the bottom part. I decided this was just the excuse I needed to install Teflon lines there.

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Stick Grip Labels

Finishing Kit

One of the items on my To Do List was to finish off all the labels on cockpit controls. I pulled out the Brother PT-2600 label maker, and cranked out labels for the stick grip, alternate air and oil cooler door.

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Glare Shield Edge - Complete

Finishing Kit

In the last three weeks I was on the road for several days, and then got nailed by a pretty bad sinus infection that slowed me down for a few more days.

I spent quite a bit of time working on the glare shield. I agonized over how to glue the vinyl covering to the aluminum glare shield. Many people use a spray-on adhesive, so I purchased a can of 3M 77 adhesive and did a test on some scrap. It seemed to work well, but you had to be quite quick to get the vinyl in place after spraying the adhesive, and I was not too happy about the risk of over-spray. I searched the RV-List archives, and found one person that used rubber cement, so I tried that on some more scrap. It was not compatible with the vinyl - the vinyl puckered up and did not lay flat.

I looked at the dozens of different adhesives at a local craft store, and found a tube of Goop adhesive that claimed to have all the right properties - sticks to vinyl and aluminum, and withstands fairly high temperatures. I did a test on some scrap, and it did a good job.

The glare shield turned out very nice. I put a small bead of Goop around the edges, as there didn't seem to be any point to trying to glue down the whole surface. For the hole where the defrost fan is, I left some extra material and wrapped it around the edge of the hole and glued it to the bottom of the glare shield.

I purchased some windshield washer tubing, and put a slit in it to cover the aluminum tube on the aft edge of the glare shield. It is almost the same sheen and colour as the vinyl, and looks quite nice.

The aluminum tube doesn't go all the way to the edge of the glare shield, as I didn't want it to hit the windscreen. I found some little rubber guards to go on the edges of car doors, and used that to cover the part of the glare shield edge that didn't have aluminum tube on it.

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Glare Shield Edge, etc

Finishing Kit

I've made progress on a few small items this week. A hardware order arrived from Aircraft Spruce, so I was able to install the data plate on the fuselage skin just behind the rear seat. It is visible with the canopy open or closed, but it isn't exposed to the air flow going around the aircraft, so it should stay fairly clean. This location wouldn't be legal for a US registered aircraft, but the Canadian regs are worded differently than the US ones.

That ACS box also had the hardware I needed to install the baggage tie downs on the floor of the aft baggage compartment.

One of the items I need to finish is the glare shield. It is a piece of aluminum sheet that extends aft over the top of the instrument panel. Some people just put a piece of plastic trim over the edge of the aluminum, but the aluminum would probably slice right through the plastic if my head hit it during an accident, and the aluminum would then slice open my head. Some people put a slit in a piece of aluminum tubing, and use that as an edge protector. That seemed like a much safer idea, but I spent quite a bit of time trying to figure out how to put a slit along the tubing. I tried several different ideas, and wasted quite a bit of tubing in the process. The first lesson I learned was to not cut the tubing to length before making the slit. If you cut the tubing to length, then screw up the first couple of inches of it, now that whole piece of tube is wasted. I eventually learned to just unroll a bunch of tube, and not to cut it off until I had successfully made a slit.

I spent quite a bit of time surfing the web, and digging through e-mail list archives. I finally come across a message by Mark Nielsen from Green Bay. He had drilled a hole in a piece of wood, and then cut a slit from the edge to the centre of the hole. Clamp the wood to the drill press table, and put a cut off wheel in the slit. Feed the tube through the hole, and voila - a slit in the tube. It took several tries to get a hole with a slit running right to the centre, lined up with the hole, but once I had the wood made it did a great job.

I will probably use some JB Weld to bond the tubing to the edge of the glare shield. I found some fairly tough vinyl leatherette stuff at a fabric store to cover the glare shield with. Now I need to sort out whether I will try to use one piece of vinyl to go on the glare shield and over the edge of the tubing. Or, whether I should just have the edge of the vinyl butt up against the tubing, and find some sort of rubber or plastic to cover the tubing. I'm leaning for the second option. I think I can put a slit in a piece of rubber tubing, and slip it over the aluminum tube.

I finished making and installing the labels for all the cockpit controls, except for the switches on the front stick grip. I had forgotten about those, and I just realized it now. I added that task to the master list. I also closed off three or four other small items on my list, and added a couple of things. Three steps forward, two steps back. Overall, the list is maybe three items shorter than it was a week ago.

I spent several hours poring over catalogs seeing which mix of vendors I should order from to get a whole bunch of hardware I need to finish various tasks. No one vendor carried everything, so you need to order from several places. I've got two more orders coming, and I need to put two more orders in tomorrow.

And, I've spent too much time watching the NHL playoffs. The Ottawa Senators are on a roll, and look to be on their way to the Stanley Cup finals. Knock wood.

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Finishing Kit

I spent several days in Toronto (not work related) over the last two weeks. I've also spent some time running around to car dealers shopping for a new car. But I have managed to make some progress on the aircraft.

I painted the cockpit and aft baggage compartment floors and installed them. I didn't install the passenger footwells, as I will need to get under there to run the wires and antenna coax to the wings later. I also didn't install the aft part of the baggage compartment floor, as I will need to crawl back there to install the elevator pushrod later.

I modified the cockpit and aft baggage compartment floors to make them removable, so I would later be able to inspect the wiring, structure for corrosion, etc. I installed nutplates and used Micro Fasteners countersunk stainless steel fasteners with Torx heads. These fasteners aren't as strong as alloy steel fasteners, so they shouldn't be used in areas where a failure could cause a significant problem.

I installed the fire extinguisher mount on the left side of the cockpit. It tucks nicely in between two bulkheads, and can be reached from either seat.

I finished the alternator wiring, vacuumed out the rear fuselage, torqued a bunch of fasteners, and finished securing the wiring for the engine preheater. I also replaced all the O-rings in the brake calipers, master cylinders and parking brake valve with ones made from Viton. The Viton seals have a higher temperature rating than the original Buna-N O-rings (400F vs 250F). Several RV owners have had the Buna-N caliper seals fail if the brakes get too hot. The brake fluid then pours over the hot brake disk and catches fire, as the normally used Mil-H-5606 brake fluid is very flammable, and has a flash point of about 250F. Several RV owners have had brake fires. The Viton O-rings can be used with automotive brake fluids, which have the advantage of being non-flammable. There are some disadvantages to automotive brake fluids (some of them attack paint, and the ones that don't attack paint do not absorb water, so any water pools in the bottom of master cylinders or calipers, causing corrosion). I'm still trying to decide whether to use an automotive brake fluid, or the aviation MIL-H-83282 brake fluid. MIL-H-83282 is flammable, but it has a much higher flash point, so it is much less likely to be ignited. It also does not attack paint. Most of the joints in the brake system are in the cockpit, so there is a good chance of spilled fluid on the floor if there is ever a leak.

Today I finished running the ELT antenna cable from the ELT in the aft baggage compartment to the antenna which will be mounted on the right side of the cockpit, with the antenna sitting on the right side of the canopy. This should provide a much better antenna transmission pattern than the other commonly used locations of underneath the empennage fairing, or right up against the bulkhead behind the rear seat.

I also finished trimming the aluminum lower empennage fairings. Last weekend I managed to get the list of items to do before going to the airport down to less than one page long. Big celebration. Since then I've knocked several things off the list, and added a few more, but it is perhaps two items shorter. Progress :)

Saturday Steve Bushby, owner of Aerolite Flight Services, in Oxford Mills, ON hosted a gather of local RV builders and flyers. There was an excellent turnout, and a good time was had by all. Thanks Steve. Steve has a beautiful workshop, and he is busy building an RV-7 for someone (unlike the USA, builder assistance is now completely legal in Canada).

Steve is working full time in his shop, providing builder assistance, custom machine shop work, aircraft repair, etc. If you need assistance, or some machining, give Steve a call.