Dave’s RV-7A Building Log

I’ve been waiting to install a few things on the back of the engine until the P-mags were installed. I was waiting to install them until I could time them. In order to time them, I need to turn the crank to top dead center #1. However, I asked Mahlon at Mattituck if it’s OK to turn the crank. He said it’s better to wait until just before firing up the engine. I think moving the cylinders will displace the preservative oil that they’ve sprayed inside each of the cylinders.

I decided to temporarily install the P-mags and then I can time them later when I’m closer to first engine start. The first thing I had to do was remove the long mounting studs that were on the left side. When using old-fashioned magnetos, my understanding is that an “impulse” magneto is installed on the left side. This is the only magneto used for starting and can retard the timing so that it fires after TDC. For some reason, that magneto needs a spacer and thus longer mounting studs. The P-mag doesn’t need them and they actually get in the way. Reading Walter’s tribulations with removing the long studs, I went right for the vice grips. I got them to turn about one revolution and then used the double nut technique to remove them and trash them. Mattituck nicely provided two short studs, which I installed instead.

With that done, I installed the P-mags. Adele was hanging in the garage with me, so I had her help in a few of the really tight spots. Her small hands were able to reach in among the engine mount and various stuff much easier.

Adele installed the oil pressure line on the engine and I installed the oil cooler. There’s one spot on the cooler flange I might trim a little bit so it doesn’t hit the engine mount. It fits great other than that. I installed the fittings in the oil cooler and turned them to an optimum angle in order to install the oil cooler lines.

I took another look at the fuel line to the mechanical pump. It’s simply too long. Ordering a custom length hose is expensive, but the standard hose is kinked way too much for my comfort. I removed that hose and added it to the pile of stuff to return to Vans.

I started looking at my options for manifold pressure. I need to route that to the two 1/8″ barbs on the P-mags and to the sender for the engine monitor. Vans provides a kit for routing the MAP behind the firewall, but I don’t see any reason to do that. It would be much easier to put the sender in the engine compartment and route a wire through the firewall. It would be one less hole in the firewall, too. There’s an extra port on the manifold used for oil and fuel pressure, so I’m hoping to use that. Connecting all the various different sized stuff together is going to take some creativity.

I’ve read in a few places that it’s a good idea to put a restrictor on the MAP line so that oil and debris don’t get in and to prevent total loss of pressure in the cylinder if something happens to the line. The restrictor also helps to even out the pulses, although hopefully the P-mags and EMS will even out the pulses. The easiest method of making a restrictor seems to be to epoxy an AD5-4 rivet into the fitting in the engine and then drill a small hole in it. I’ll investigate a bit more to make sure that’s the best option.

I was poking around and found an alternator belt that Mattituck included in the goodies box, probably because they mistakingly thought I ordered an alternator. I knew it would be too long as it was a 7365, but I thought I’d see how much too big. It was about an inch too long.

I started out by mixing up some epoxy with the West Systems Microlight filler. I wanted to smooth out a few spots on the cowl ramps and fill in the holes I had to drill. Making the ramps perfectly smooth isn’t really necessary, but I might as well practice on an area that won’t be seen. As it turns out, I mixed up the goop a bit to runny. It filled in fine, but sagged a little before setting up. It’ll still be good enough for the ramps.

The next logical step after installing the baffles was to install the Filtered Airbox (FAB) air intake plenum. I’ve been contemplating laying up an extra layer of fiberglass on a few areas that have some cracking, but then figured I could always fix it later if it falls apart. After installing all of the screws, it’s on there very solid and clears the starter just fine.

There was still one clip I needed to make on the right side baffles. It’s not clearly depicted on the plans, but the instructions mention it. It’s fairly obvious that something is needed otherwise the aft baffle side will push outboard too much.

Next up was the oil cooler. I made the spacers for mounting the oil cooler to the baffles. As Dan points out on his log, it’s a good idea to place washers on both sides of the spacer tube. It’s not in the plans, so you have to subtract 3 to 4/32″ from the dimensions.

I decided to wait to install the oil cooler until I have the P-mags installed. However, I did install the fitting for the manifold pressure. I need to figure out how to hook this thing up to both P-mags and the transducer for the engine monitor. (top blue fitting in the picture)

Time for Easter dinner!!

I started off my mixing another batch of epoxy. I decided to reinforce the ramp extensions I made previously. Before I laid up just 2 layers of fiberglass and it seemed a bit flimsy, especially since the baffle seal will be pushing against it. I laid up 3 strips on each side to reinforce the forward edge.

I then moved on to finishing up the riveting on the baffles. There were several rivets that I had to buck. A few aren’t very pretty, but they’ll hold just fine. I also drilled the holes in the bottom flanges that are safety wired together to wrap around the bottom of the cylinders. I also reamed all of the holes for screws 1/64″ larger per the instructions to allow for movement.

I then decided to mount the alternator. I’m not sure why I put this off so long. The parts have been sitting primed on my bench for weeks. I guess I was just concentrating on the baffles. Anyway I installed it.

I mounted the starter ring gear and estimated that I need an alternator belt 33″ inches long. Van’s suggests starting with a Gates 7350. I looked up that belt on www.rockauto.com, which states it is 35-5/8″ long. I’m not sure if that’s an inside or outside diameter, but I’m guessing it’s a bit too long. I’ll stop by the local auto parts store and see what’s available.

From there I figured it was time to install the baffles for the last time. It all went very smoothly, although I did manage to scrap a bit more paint off the rocker covers. I was hoping to be able to install the screw behind the dipstick, but I just couldn’t contort my fingers to get back there. I snapped a picture of the safety wire, cut it, removed the dip stick tube, installed the screw, and re-installed the dip stick tube.

Big day with some big accomplishments (as long as those stupid baffles don’t need to come off again).

No building last night. I was busy with TurboTax and trying to sort out which EFIS to use. I was sold on the Dynon D100 EFIS and D120 EMS until Advanced Flight Systems announced their new offerings last week:

There are several things I like about these new units. First and foremost, the screen layout is much better. By putting the engine gauges along the bottom for split screen, the EFIS can still be full-width. The airspeed and altitude numbers are also shown next to the tape pointer. I’ve seen a few people complain about that on the Dynon. The AFS units can also display the AOA on screen. Many people say you want the AOA right in your line of sight, but I think having it on screen will put it still within the periphery of vision. Also, I’ve always liked the AFS engine monitor’s ability to display the trim indicators. It’ll be nice to remove those ugly things from the panel.

The only drawback to the AFS units is the timeline. They are supposed to ship in July, which could impinge on my hopes of flying this spring. I called AFS to get a more firm timeline and answer some other questions. I was patched through directly to Rob.

Q: Can the EFIS display a CDI.
A: Right now it can interface to a serial GPS or the SL-30. They are working on an ARINC to serial converter (for an extra cost) so the EFIS can also talk to the GNS-430. It will hopefully be available by Oshkosh.

Q: Is the July delivery date pretty firm?
A: Some units may ship in June, but they are getting many orders. They’ll ship in July at the latest.

Q: Is there a battery back-up available?
A: Yes, it’s a $120 option for either EFIS or EMS.

Q: Are there any feature differences between the 3400 and 3500 besides screen size?
A: No. They run the same software. The only difference is the screen size. The 3400 is actually a little bit brighter, but the 3500 looks brighter (probably because it’s bigger).

Q: Does the EFIS provide an altimeter encoder output? (The transponder needs this.)
A: Yes, a serial output.

Q: Do the units use a separate analog box like the AF-2500?
A: No, everything is included in the one box now.

Q: Does the unit use a mounting tray?
A: No it mounts to the panel just like the AF-2500 with 4 screws.

The answer for every question was just what I was hoping. With the ability to display a CDI, I can delete the expensive Garmin CDI from my shopping list. That’ll actually make the AFS units very price competitive with the Dynon D100/D120.

I placed my order for an AF-3400 dual screen EFIS/EMS system with the AOA and one battery back-up for the EFIS. They aren’t even requiring a deposit yet. They’ll take deposits when they get closer to shipping.

Rob said he could send an AutoCAD file over to Ross to use for panel cutting. Pefect.

It’s nice to have this big decision behind me. I’m a little nervous about using a totally new, untested system. However, Rob has an excellent reputation with the AF-2500 product that’s been out for a few years. I’m sure he’ll deliver the goods with the AF-3400.

Back from a few days in Green Valley (near Tucson) with my folks. It was good to see the sun again.

I worked a bit more on trimming the baffles to the ramps and the side ramp seals that I made. It looks pretty good. Hopefully that is the end of the baffle trimming.

I thought I was done with the baffle trimming a few weeks back, but I forgot about the ramps. I did several iterations of installing the top cowl, marking the baffles, removing the baffles, trimming on the band saw, and re-installing the baffles. The ramp extensions I made are working perfectly. I’ll probably add a few more strips of fiberglass along the exposed forward edges just to beef them up a bit.

The cowl is now to the point where it sits in the correct position again. I still need to trim a bit more to get a 3/8-1/2″ gap. Just a few more work sessions and I think I’ll have the baffles mostly done. I don’t know if it’s the nice weather we’ve been having or the prospect of moving past the baffles, but I’ve been enjoying the project more lately. It was getting to be quite a grind for the past month or so. Unfortunately, I won’t be able to put in any time for the next few days. And then I’ll really be driving hard to finish it up.

I worked more on riveting the baffles together. It’s slow going due to all of the weird angles. It’s very cool to finally be putting these things together. I can’t wait to install them on the engine for the last time.

I worked some more on riveting the baffles together. The left aft section is really complicated with the oil cooler doubler and the little box I made to avoid the baffle jog. I’ve swapped the squeezer sets at least a dozen times already, and there’s still a few I’m just going to have to buck.

I also spent some time trying to figure out the attachment of the throttle quadrant to the panel. Bill has some good pictures of how he mounted his. Scott also posted a picture on the VAF forum of his mount.

Also in the news are the new EFIS systems from Advanced Flight Systems. They look like sweet systems. They claim that the EFIS interfaces to the VOR and GPS. If it can act as a CDI, that would be sweet. AFS/ACS has a great reputation with their AOA and EMS.

The ramps turned out great. I sanded off the excess epoxy. I can see that it made a great bond and it’s plenty strong. I’ll probably add a bit more filler and sand one more time.

Today was my first adventure with fabricating fiberglass. In order for the front baffle bulkheads to have something to seal against, I decided to seal off the inboard edge of the intake duct ramps. I followed this great tutorial on fiberglass. This is my work area after I was done.

I laid up two layers on each side that was shaped like a trapezoid, 5″ along the bottom, 5″ high, and 2″ wide at the top. It’s a little hard to see, because it’s mostly transparent. It turned out great! (Doh! My birkensocks got into the picture.)

I started out trying to use duct tape and saran wrap and mold over the top of that. It was a bit of a mess, so I quickly ditched all that, cleaned up the cowl, and just laid the fiberglass right onto it. Luckily I had already roughed up the surfaces of the cowl with some sandpaper. I followed the tutorial above to the letter, except I didn’t bother with the Dacron peel-ply. I’ll try that next time. I’m using bidi fiberglass, so it’s really pliable. I was able to fit it actually how I wanted it.

Fiberglassing isn’t too bad. Hopefully my buddy Steve doesn’t read that. He’s got a fiberglass sailboat and a nasty sensitivity to epoxy. I’ll be conscripted into helping on his plastic boat!

I spent a few hours out in the yard. The grass is growing again unfortunately. Around Seattle, the grass stays nice and green all winter without growing. It’s great. And then Spring hits and it’s a half foot tall in 2 weeks with tons of moss.

While the fiberglass set up, I worked on riveting together some of the baffles. It seems like there are 100 parts. I riveted on the right side stiffener, and most of the oil cooler doubler. I was lazily following the rivet call-outs on the plans for the doubler. Big mistake. The rivets along the bottom need to be 426 with the flush head forward. On the bright side, I got some extra practice at drilling out rivets. Thanks Vans.

Well, it’s all finished. First flight was today, and it went great. (I wish.)

Last night I took 4 kids from the Math Team to a competition. (I’m the Math Team coach this year.) They did pretty good. It went pretty late, so I didn’t have any time for the plane.

I mixed up some epoxy, added some flox, and permanently attached the ramps to the upper cowl.

I put a heat lamp on them for a little bit to help kick off the reaction.

I also cut the hole for the prop oil line a little larger in the right front floor. I have a rubber grommet that fits pretty well. While I had the floor out, I also added a diagonal bend. I never quite figured out how it was supposed to work, but now it’s obvious. I didn’t bend it too much so that everything I already drilled still fits.

I also drilled the little box I made for the baffle jog.