Category: Fuel System

Fuel Calibration—-Yay and Nay!

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Posted: September 15, 2021

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September 15, 2021 – I started fuel tank calibration.

I jacked up the tail to level, and started the calibration on the left wing. In hindsight, I kind of did this maybe the hard way, but it worked.

I bought 5 gallons of fuel at a time (my hangar has fuel), and transferred that to a marked 1-gallon jug. I did the Dynon procedure, where you tell it how much is full, then click “Add” every two gallons.

Here’s the screen as fuel got added:

Got to 21 gallons and clicked “Full”. I rebooted the Dynon and got a good reading. Actually it doesn’t read above 15 gallons or so, but that’s a “feature”.

Now to the right wing.

I drained the left tank 5 gallons at a time and started the transfer to the right tank.

Maybe it’s  worth noting that the right tank has a flop tube for fuel pickup, which moves the fuel float to the next bay outboard in the tank. As  I started filling the right tank, the readings didn’t change.

The first time I tried this, I got to 12 gallons, went around to press “Add” on the screen, and saw that the Dynon system had shed its load because the battery couldn’t keep up. Oh, well, just as well. I really didn’t want to get all the way to 21 gallons with this problem. But the next day I decided to try again. Same problem. I filled up to 21 gallons. The Dynon asked me if I wanted to use that calibration, even though it wasn’t successful. I answered yes, but after I restarted, the right side still showed the annunciator for CAL. My inspection is scheduled, so I asked my DAR as well as the test pilot if this was going to be an issue. They both said no, so I’m going to defer this until after the airplane flies.

I’m assuming I’ll need to pull the tank.

So I drained 10 gallons from the right side, and put them in the left. My test pilot asked for 1/2 tanks for first flight. Oh, by the way, I bought a battery-powered pump from Harbor Freight. Took no time to drain a 5-gallon can.

Time: 6:20

Category: RV-7, Fuel Tanks, Avionics, Fuel System, Panel

Wing Tasks

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Posted: February 23, 2021

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February 23, 2021 – With the wings on, I started doing various tasks that need to be done while the wings can still come off.

Fuel Tank Attach

After quick verification that the wings were in the correct position from the previous drilling 5 years ago, I drilled the fuel tank attach brackets. This was a simple matter of using a drill bushing to center the hole in the fuselage bracket slot.

When the wings come back off, I’ll install the nutplates for the attach bolts.

Fuel Lines

The next step is the fuel line connections. These are the vent lines and the main fuel feeds from the tanks. The right tank is routed differently because I have a flop tube installed there. The main fuel connection from the left side is a straight shot into the fuselage.

Wing/Fuselage Fairings

There are fairings all the way around the wing root that enclose the gaps you see in the above pictures.

There is a short section underneath where the fuselage skin is attached to the wing skin on each side. I used a hole-finder to start these holes, then enlarged the holes up to the correct size for the screws.

The next part is the large wrap-around panel that wraps around the leading edges of the wings.

These panels have pre-punched holes that match open holes in the wings. Holes do need to be match-drilled to the skins of the fuel tanks.

Time: 6:00

Category: RV-7, Wings, Spars, Fuel Tanks, Fuel System

Continued Cockpit Fuel Lines

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Updated: February 6, 2020

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February 6, 2020 – At last! A small victory! I have successfully made and fitted two of the fuel lines in the cockpit from the fuel selector to the wings.

A 4-foot length of 3/8 tubing has been whittled down to about 1 foot before I got the hang of this.

I learned that I needed to flare the outboard end of the line IN the airplane.

I made the right side inboard line in an alarmingly short period of time, and it was harder because it has to work around the plumbing for the pump and filter.

I removed the outer kickplate brackets that the outboard tubes will go through. I added holes to each one that would line up with the travel of the fuel tubes.

Time: 3:35

Category: RV-7, Engine Fuel, Fuel System

Continued Cockpit Fuel Lines

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Posted: February 2, 2020

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February 2, 2020 – I continue working on the cockpit fuel system.

Not much to tell…I have a nice 4′ long piece of 3/8 aluminum fuel line that is shrinking away to nothing because of my trial and error… Picture shows a nice section of tubing that would work if I can get it to run through the angle instead of outside…

Time: 2:45

Category: RV-7, Cockpit, Fuel System

Cockpit fuel system

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Posted: July 9, 2019

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July 9, 2019 – I worked on assembling some of the fuel lines in the cockpit.

I needed to make the straight fuel line that goes from the fuel pump/filter assembly to the firewall. pretty simple; it’s just a bend and a straight run. I’m pretty pleased I got the measurement right the first time. I did have to slide the pump and filter in their clamps a little bit, but that worked.

The plans call for securing the line underneath the bracket with a piece of foam, but there’s no more information than that.

Here’s a shot of the tube under the bracket:

I think I might put an adel clamp on the forward end of the bracket and around the tube underneath. It’s pretty solid but I don’t want it to just hang there and vibrate.

I also installed the line from the selector valve to the filter. Kind of tight, but it does fit.

Time: 1:10

Category: RV-7, Cockpit, Engine Fuel, Firewall Forward, Fuel System

Started center section cover

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Posted: January 22, 2018

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January 22, 2018 – Since my next step on the firewall is to install the recess, I moved to the cockpit floor cover for the fuel system.

I had previously done some small work on this, but didn’t know if I’d be installing a fuel boost pump in this location. I have the stock boost pump and filter from Van’s, along with the cover, so I started in on this. The cover needs to be modified to fit the pump assembly.

The long piece of the cover gets cut to accommodate the support for the pump and filter. The piece in blue plastic is the new bracket that supports the pump. An additional notch needs to be removed from the long cover after it’s shortened.

The housing for the fuel selector valve also gets modified.

Then I had to crawl into the airplane and drill the mounting holes for the covers. I temp installed everything to get the positioning just right.

Once everything was drilled, I took it all apart to deburr and prep for paint.  One last thing I had to do was bend the louvers for “cabin heat”. I put that in quotes because the RVs are known for not having adequate heat in the cabin right out of the box. These louvers were a little tricky to get the hang of at first, but I think I did pretty well.

Here’s a picture from up above again. You can see that the louvers at the top of the picture are just cutout and not bent to direct the air:

I used a hand seamer with a radiused strip of aluminum to make the bends. I used the table to back up the bend on the back side.

Here are the finished louvers:

Hopefully the weather will cooperate and I can get this stuff painted soon.

Time: 5:15

Category: RV-7, Fuselage, Cockpit, Fuel System

Canopy and windshield work

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Posted: September 15, 2016

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September 15, 2016 – In the last post I described how I prepped the forward top skin for installation before I could install the windshield. One of the things I had done previously bugged me a little bit as far as maintainability is concerned.

The fuel vent lines are clamped in place as they run from the inlets to the tanks. I realized when the top skin is installed, I wouldn’t be able to get to the top clamp if I ever had to remove a vent tube. So I removed the screw and nut for that clamp, and I installed nutplates in the left and right top gussets.

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Here’s the screw from underneath:

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I moved on and started preliminary trimming of the windshield. I have a pretty nice 3/16″ or so gap between the windshield and the canopy. I’m just going to clean that edge up to prevent future cracking.

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My friend Floyd came over to see the project, and to help me drill the inner side skirt braces. Then I prepped, painted and installed them.

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I started on the aft blocks that provide the stops for the canopy. There are pins in the canopy frame that will go into holes in hard lastic blocks, and will secure the aft end of the canopy when it is closed.

Before I could start those, I realized I had left out some rivets in the side skins right at the aft ends of the tracks. I installed them so the skin was tightly in position.

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The plans call for the channels that the blocks go into to be 1/8″ from the outer edge of the canopy decks to allow for clearance of rivets. I drilled for that.

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One little problem, which really has everything to do with my canopy still being just a hair too wide (see previous posts). here’s how the pin on the canopy frame is positioned in the channel for the block on the left side:

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The pin should go into the block more inboard than it is. I decided that I have enough clearance from the rivets to move these channels a little bit outboard, closer to the canopy frame on each side. I thought maybe I could make some of these channels, but I decided to go ahead and order two new ones from Van’s, and I’ll drill the new ones so they are a bit outboard from where these are.

Here’s a picture of the inner skirt brace and an aft block shot from inside with the canopy closed:

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Time: 7:30

Category: RV-7, Fuselage, Forward Fuselage, Skins, Canopy, Finish Kit, Fuel System

Worked on fuel selector valve

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Posted: November 18, 2015

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November 18, 2015 – I started to do some preliminary things with the selector valve.

I’m using the Andair selector valve. I didn’t do a lot with it. I drilled the 1 1/8″ hole where it will mount, then I drilled the three attach screw holes.

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I also installed nutplates on the flange of the valve where it will attach to the box later on.

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Time: :50

Category: RV-7, Fuselage, Cockpit, Fuel System

Made and installed fuel vent tubes

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Updated: November 18, 2015

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November 11, 2015 – I made the two fuel vent tubes.

The fuel tanks are vented using air from fittings installed in the belly, routed up through the fuselage and out to each tank in the wings.

There are several somewhat complex bends. The tubing is soft and easy to bend, but it can be overbent, which will damage it. I had read that it helps to use stiff wire to lay out the bends. I used a coat hanger. Not sure how much it really helped, but OK.

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I installed the fittings in the sides of the fuselage where the tube connects and goes out to the wings.

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I just slowly bent the tubing to fit.

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The worst part was down at the side fittings, because there are two or three sharper bends. I switched out the fittings for a better fit. The original configuration is for a 90 degree fitting. I put in 45 degree fittings and got a better fit.

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I also found it easier to install the clamps as I went. This held the tubing in place so I could fine-tune some of the bends by hand.

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The tubes don’t look like they came out of Boeing, but I’m pretty happy with them.

Time: 5:00

Category: RV-7, Fuselage, Forward Fuselage, Fuel System

Some small fuselage stuff

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Posted: November 3, 2015

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November 3, 2015 – I did a couple of small items today.

I crawled back into the tailcone and installed the shoulder harness brackets.

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I had previously cut the fuel vent fittings that are installed under the belly and take air in to vent the fuel tanks. I sealed on some screen to keep the bugs out, then I installed them in the belly. The sealant job could probably be prettier…

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Time: :30

Category: RV-7, Fuselage, Aft Fuselage, Cockpit, Fuel System

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