Feb 20, 2024     tightened all fuel fittings - (3 hours)       Category: Fuel System

Some of the fuel line fittings were just finger tight as I positioned and finalized routings and wiring and so forth, so after I finish the fuel vent tank to fuselage plumbing I went back and put a wrench on every fitting to confirm that they were all tight. as I checked each one, I put a stripe of torque putty at that location to signify that it was tightened.

  Feb 15, 2024     Finished up fuel tank install - (5 hours)       Category: Fuel System

I safetied the fwd inboard fuel tank supports.

The bolts go into a nut plate that comes off the inboard tank rib. The shank of the bolt rests in a horizontal slot in the steel bracket coming off the fuselage. This bolt doesn't get torqued, just snugged down so that the washer will no longer turn.

The idea is that during a crash if the wing gets bent back, this structure will pull apart and not yank the end rib out of the fuel tank. But because if the way it's put together, it needs more safety than what's just provided by it sitting in a nut plate not properly torqued down.

The assembly print have you safety wire the head of the bolt, but really don't call out a specific dimension on where to drill the Hole for the safety wire to run through. I just followed standard industry convention with edge distance and so forth and ended up with a number 40 hole about 3/8" from the edge of that tab, which is gobs.

After that was done, I bent up a trial fuel vent line out of scrap to get the bends and leg lengths right.

Note that the assembly print calls for the fuel vent fittings at the wing root to be pointed forward and reflects a vent line routing up over the forward tank attach bracket because of that.

In my case, the brothers I bought the wings from had oriented those fittings down. If I followed the suggested routing, my fabricated lines would immediately have to do a u turn back up, then fwd to clear coming over the top off that bracket structure. Thats seems like a lot of additional bends and unplanned low spots for water collection and whatnot.

It's just a vent line, so as long as it doesn't get plugged or chaffed somewhere there isn't much that can go wrong here, but I spent quite a bit of time investigating this to make sure I wasn't missing anything obvious.

Depending on whether you have aerobatic flop tube pickups or not, there are multiple suggested routings for both the fuel intake and vent lines. After reviewing what other folks have done, I elected to go under the forward tank attach bracket with a much simpler run than what would have been required to go over the top or through the bracket lightening hole.

It's her to tell in the pictures below, but there's about 1/2"-1" clearance between the vent line and anything else in there.

  Oct 17, 2022     fuel selector and cabin fuel lines - (2 hours)       Category: Fuel System

Secured the fittings to the selector with loctite 648 per andair service letter. The options were to stake them with a punch or apply loctite. I ordered the specified loctite via amazon a while back because its a fuel proof basically permanent version. that stuff isn't coming apart.

Installed date selector and snugged up the feed lines, then once they were fixed in their final position, measured cut and flared to teh measurement that I obtained to the tank fittings while the wings were installed. this dimension was approx. 3 1/2" on one side and 3 5/8" on the other from the fuselage skin to the shoulder of the cone on the tank fitting. Moral of the story; If you rough these in early in the build, you better leave yourself at least 4" to work with or youre likely going to be building new ones.

Fortunately, I had done that. no drama and I think that everything should mate right up when the wings go back on.

  Aug 29, 2022     Fuel boost pump - (5 hours)       Category: Fuel System

I believe that I've finally almost wrapped this up. Fuel pump is permanently bolted to the pallet with An4 bolts up from the underneath side with blue locktite on the threads. Locally grounded from the negative terminal via a wire and a ring terminal to a nut plate in one of the side angles.

Vans print calls for the line from the pump to the firewall to be sandwiched in foam between the floor and the tunnel cover. This has always seemed kind of shade tree to me. Plus, since I'm going with a taller tunnel cover, that doesn't seem practical, i.e. that would be a really tall stack of foam.

With that in mind, I decided on a different solution. I added a crossbar fwd on the pallet to support an adel clamp on the output line mid-span between the pump and the firewall. Probably overkill because it certainly wasn't going to rub on anything but now I've ensured that it's captured rigidly and the the firewall elbow isn't able to rotate if the jamb nut loosens up on down the road. The whole plumbing run is now very securely captured and can't rotate, chafe, or otherwise misbehave.

Fabricated the output line, installed stainless steel AN fitting at firewall. Output line from pump to firewall is just finger tight at this point.

There is clearance between the wire bundles and both the floor and the lower face of the boost pump mount pallet, but I've ordered some snake skin from spruce and when it arrives I'll pull the pallet up and add it as additional chafe protection. I'm also going to add a piece of corrugated conduit under there so I can route the wire from the OAT probe after the wings are on without pulling the assembly out again. I believe that OAT probe will be the last wire to run aft thru the tunnel. After snake skin and conduit, I'll permanently install the pallet and all plumbing.

Feels good to get this wrapped up. I was really getting sick of plumbing. Unless something leaks, the only plumbing left is in teh wing root, and that can't happen until the wings go on.

  Aug 31, 2021     tank to selector fuel lines - (4 hours)       Category: Fuel System

Took a lot of measuring and a couple of pieces of scrap, but eventually I figured how to make these with all the bends done with a bender on the bench before installation. Reminds me of those puzzles where you have to figure out how to turn two twisted nails to get them apart. You think it's not possible, but then you turn it in one very specific sequence and it just falls into place.

Specifically, they start as a straight tube 31" long, then from the selector outward, the bends are as follows (clocked in different but hopefully obvious directions) a 90* 2.5 inches from the end, then 3" to a 45*, then 17" to the next 90* then 3.5" for the final 90* out through the side wall.
Doing it this way makes them pretty, but will require that they be flared in place. I'm holding off on that and will likely take them out and put them on the shelf for safekeeping when it comes time to fit the wings.

EDIT- Hey idiot, it's me from the future. Don't take these out once they're in place. If you do, in about a year you will route wire bundles through those cover support ribs, then discover that after you unscrew the F-782B from the fwd face of the spar box, you can't get enough slack in the wiring to maneuver those really pretty fuel lines through.

You will then bend and tweak those lines for way to long trying to find a way to get them in there, then ultimately give up and make new ones in two chunks with a union ref. august 2022 log entries. also, it's bad form to have fuel above electric either where it can drip during a leak, or where an electrical fire can sent flames upward onto a fuel line. I've know this for years, so I built per print, but in the outboard corners, the wiring crosses in front of the fuel line then tucks underneath to go through the passthrough holes in the spar. I'm going to have to do chafe protection and standoffs in that area for my own peace of mind. I'm not so sure it was really any better in this case that just running full lines through the top hole. It certainly would have made the line fabrication and runs easier.

  Aug 30, 2021     fuel vent lines - (5 hours)       Category: Fuel System

Fabricated the external fuel vent fittings from -4 bulkhead unions. Turned the lower end down by lightly chucking them up in my drill press and then eliminating the threads with a vixen file. Cut the ends to a 45* angle per print with my band saw.

Tons of people on VAF talk about how awful these vent lines are, so I did a google search and found a video by Karetaker Aero than had some good tips for where to start with them etc. It's worth checking out.

CAUTION- the -8 screws that go into the lowest adel clamp on the fwd end of the run need to be shortened or they will hit the skin if you snug them down. I screwed a fiber lock nut down on a couple of washers and then ground them down to the end of the nut on my belt sander and that was about the right length, with just a thread or two showing through the nut plate after installation.

Other than that, no drama, just lots of off & on to eyeball where the bends should be.

These are not torqued yet, because I haven't fabricated bug screens to go on the front of the external fittings.

  Aug 24, 2021     Boost pump install & cover - (10 hours)       Category: Fuel System

Holy cow, this has been a lot of work for such a simple thing. I've devoted probably another 10 hours spread over several days to this since my last entry.

My friend Robert summed up the Van's boost pump installation nicely on his RV6; "When I took that cover off it looked like somebody had shoved a french horn under there"

There are tons of fittings and lines going every which way, and it seemed like there had to be a better way, so I decided to go with the comparably priced EFII boost pump.

Lots of guys have used this pump in all sorts of configurations, but most of them have been a variation of a stack that fits under the Vans OEM "dog house"

I did TONS of trial fitting, line bending, etc. and ultimately came to the conclusion that I'd rather have a clean sheet tunnel cover that didn't stick up so much. and that I could put a couple of drink holders and maybe a fire extinguisher on top of.

To that end, I fabricated a mount out of .050 2024-T3 which attaches to some angle. then the whole thing gets attached to the center two floor stiffeners using the 4 holes and hardware called out on the Vans print. plus two more #8 screws about 4" aft of the fwd holes called out for the lightweight tunnel cover. This is actually fewer holes than are called out on supplemental print for Vans High Pressure Fuel Pump Installation drawing.

The pump & filter just bolt to the tray, the mounts to the floor stiffeners with 4 #8 screws, then a cover made of .040 2024-T3 drops over the whole thing and then transitions into the factory tunnel cover about 8" aft of the cabin heat louvers. The cover also ties into the fuel valve cover. Due to it's shape and all the supporting stuff that it attaches to, everything is very rigid and is plenty strong enough to mount a fire extinguisher or O2 bottle on top of without further internal stiffeners, if I decide to go that route.

The best part is that I still have the empty space under the original cover plate for wire and pitot/static runs.

The entire thing sticks up 2 & 3/8" above the level of the floor stiffeners and I will still hopefully have room to stretch out a little on long flights. About the only down side I see is that I will need to have carpet custom made for that area since it's a different shape than either of the factory configuration covers, but I'm okay with that.

I really wanted to get this wrapped up today, but we're having an end of summer heat wave right now and by mid-afternoon, it was pushing 95 degrees in my garage so I'll come back to this another day and install all the nut plates etc.

Really glad to get this done. I spend way to long on it, but I'm happy with the end result.

  Aug 04, 2021     EFII fuel boost pump - (20 hours)       Category: Fuel System

I've been pondering this for a while and working on it for a couple of hours here and there without much progress. I tried a ton of different configurations for this over the last week or so and think I finally have a handle on it. Lot's of guys do these with the filter stacked on top and a bunch of curved tubes going every which way. The rats nest of fuel line was one of the things I was trying to get away from, and after measuring, sketching, trial fitting, etc. I think I finally have a handle on this.

I'm going to flat pack the assembly in basically the back 1/2 of the tunnel and raise the tunnel cover by about 2" This will simplify the plumbing runs, leave lots of access under the selector valve for what's going on there, and give me a place to put cup holders and maybe a fire extinguisher.

Plumbing and trial fit done, although theres still a lot of fab work to make this happen. Lot of work for cup holders!