Archive

Archive for November, 2012

Installing ELT – 5 hrs

November 29, 2012 Leave a comment

Thursday Nov 29, 2012

This week I have been working out how I will install the ACK E-04 406 MHz ELT. For weight and balance reasons I want to mount it as far forward as possible. It’s only 1.8 lbs but every ounce behind the baggage compartment is important. Vans makes an ELT/ strobe power supply bracket that mounts to the side stringers in the bay behind the baggage compartment but I have read that the rudder cable rubs against it, so I am not inclined to go that way. I decided to try to make a custom bracket from Alclad scrap that mounts lower than the Vans bracket away from the rudder cable.

I started by sketching out a concept and then I cut out cardboard pieces as a model. It will have a shelf just large enough to mount the ELT tray and two ribs will attach it to the stringers of the fuselage. I transferred that pattern to some .020 alclad sheet which is easy to cut with snips and to bend to shape. After fitting it and making some tweaks to that, I was satisfied with the fit and I transferred the pattern to .032 alclad sheet which is thick enough to be quite stiff. Here is a photo of that design after I match drilled it to the two fuselage stringers.

Then I took the parts out out, drilled all the holes for rivets and nutplates, dimpled holes and deglossed it. If you look closely at the photo below you can see two diagonal gussets that support the ELT shelf where it overhangs the vertical rib. Those gussets are directly under the mounting points of the ELT tray so the loads are carried directly into the stringer.

My next step with this is to prime the parts and rivet them together first, then pop rivet the assembly into the fuselage. There will be nutplates for the four screws that mount the ELT tray so it will be easy to install and remove. This will all make more sense when I can post photos with the ELT installated.

Advertisements
Categories: ELT

Installed Transponder Antenna – 9 hrs

November 18, 2012 Leave a comment

Sunday Nov 18, 2012

This post summarizes most of the things I did this weekend on the project.

On Friday the transponder antenna I ordered from Delta Pop Aviation arrived in the mail. This is a low drag blade antenna that I will mount on the bottom of the fuselage just behind the baggage bulkhead. Delta Pop also has a UAT ADS-B antenna that looks identical that I also plan to install when I get around to ordering it so I made two identical doubler plates. I want to get the metal work done now before I install the rear canopy window.

Because the antennas are narrow I bent the doubler plates on each end to add ribs to help spread the loads laterally into the skin. I would have used .040 thick alclad for these but all I had was .032 so I used that.

I used the doubler plates as templates to drill the holes in the fuselage skin. This view shows the transponder antenna doubler location on the right side of the fuselage.

Here is the UAT antenna doubler on the left side. At these locations the two antennas will be two feet apart – the minimum recommended distance. The will also be about 3 feet from the comm antennas which I plan to put under the seat pans just aft of the spar.

For installation I followed the recommendations on the EAA website for this type of antenna. I used star washers under the lock nuts to get good electrical grounding and I put a bead of Alex Plus siliconized caulk on the face of the antenna to seal out water. The benefit of this material is it won’t interfere with paint adhesion around the antenna when the day comes to paint this baby.

After I torqued down the screws the antenna seemed pretty solidly attached so I think the .032 alclad was adequate. Still this thing is somewhat vulnerable sticking down here no matter how thick the doubler is and I’ll have to be careful not to bang into it.

I also riveted the outboard subpanel ribs to the forward fuselage. This photo shows some of the more difficult rivets. I left the center subpanel clecoed because I will need to remove it to cut a hole for the radio stack trays which are longer than about 8 inches. Right now I expect that will be the SL-30 and GTN-635 trays.

I also played around with a bracket for the headphone jacks. I’m trying to decide where to put these and one option is on a small bracket slightly recessed behind the panel near the air vents. My only question with this location is whether it will be in the way of passenger knees. I made a sample bracket and clecoed it to the panel edge as an experiment. Still undecided. I wish I had seats installed so I could judge it better.

I also did some electrical work. Since I installed the Skyview network hub last week I cut the wires on the ADAHRS I had routed to the forward fuselage and terminated them with a Dsub connector. Now the ADAHRS plugs into the hub. I also installed another Dsub on the remaining 15 foot long run of wires I cut to make a network cable for the run to the panel.  I mated that connector to the hub also and ran the wires down the right side of the center tunnel. So far it does not look like I reduced the overall wiring with the hub located here but I still have wires from the pitch and roll autopilot servos to run. The control signals for those will also get routed to this hub so it will ultimately have four out of five ports occupied.

Installed Skyview Network Hub – 1.5 hrs

November 14, 2012 Leave a comment

Wednesday Nov 14, 2012

I have been planning out all my wire runs from the wings and tail cone through the main spar to the avionics and I realized that things are going to get pretty crowded. So to reduce the number of wires a bit I decided to mount a Skyview network hub behind the baggage compartment. To that I can route the ADAHRS, pitch servo, and roll servo signals and just run one network cable from there to the Skyview PFD. That will reduce the number of wires through the main spar access holes by eight if my estimates are correct.

The Skyview hub is nicely made and mounts on a plastic base. In my case I mounted it to the vertical rib behind the baggage bulkhead with four #6 screws and locknuts. I will re-terminate the long ADAHRs cable with a new 9-pin Dsub connector and plug it right in here.

Categories: Avionics

Installed Flap Position Sensor, Riveted Firewall Recess – 5 hrs

November 10, 2012 Leave a comment

Saturday Nov 10, 2012

For some reason I decided that it was time to install the flap position sensor behind the seats. But first I removed the flap motor channel and replaced three universal head rivets with flat head rivets because the canopy release bar was rubbing against them. Best to get this done now.

The flap position sensor is a Ray Allen POS-12 linear potentiometer. The method of installation came from Mike Bullock on his web site (thank you Mike). I used the same model airplane clevis’s and control rod specified on his site. I also installed a 3-pin Molex connector on the POS-12.

Installation in the flap motor cover was easy. I did a trial fit of all the parts first with the flap motor in the fully raised position and marked the channel where the POS-12 was located with the sensor arm fully extended. The clevis’s were set at the mid point of the threads so could adjust the overall length of the rod at final installation. In this photo you can see the POS-12 mounted to the channel with two #4-40 screws and some cheap lock nuts I picked up at True Value Hardware. I’ll replace those later with better quality parts. I also installed a couple of tie bases to route the wires.

Here you can see the sensor installed. The linkage uses just about all of the 1.2 inch range of the potentiometer. I used my car battery to drive the mechanism up and down a few times to check function and alignment. I used the clevis’s to set the linkage so the POS-12 does not drive into the stops at either end.

The lower clevis is attached to a 1-inch Adel clamp using a small part I made from aluminum angle scrap. I left just enough material on one side of the angle to provide a shoulder that prevent the part from rotating on the Adel clamp screw. One small hole is all that is required to attach the clevis.

At the upper end you can see the POS-12 with the other clevis attached. All that is left here is to route the electrical wires for the POS-12 and the motor forward to the avionics bay.

Another big step today was installing the firewall recess. I wanted to keep this open as long as possible  because I makes it easier to get to things up front but I will be installing the engine soon and the recess needs to get installed first. I cleaned all the faying surfaces with scotchbrite and Simple Green first, then wiped them all down with MEK. I used Flamemaster C1900 sealant which I ordered from Sky Geek. After I mixed and applied the sealant I clecoed on the recess and began riveting. I also used C1900 to plug all the small holes in the corners. This photo shows the recess installed after I remounted the battery box and torqued it.

Installed Heater Box Cable – 1.5 hrs

November 7, 2012 Leave a comment

Saturday Nov 7, 2012

Tonight I installed the cable that opens and closes the heater box valve to regulate warm air flow into the cabin. The cable appears to be a couple of feet too long and I can’t do the final installation until the instrument panel is installed but I wanted to get everything set up now while I have good access to the valve through the firewall recess. The standard installation method is to mount an Adel clamp using the heater box screw but when I did that the cable was bent awkwardly so I modified the approach by making a bracket from 3/4 x 3/4 aluminum angle and I mounted the Adel clamp to that. This results in less bend of the cable and smoother action. It also moves the cable far enough aft that I did not have to drill a hole in the firewall rib for the cable.

 

I installed the F-782 also and saw that I needed a notch to allow the cable to pass. You can see the notch I made in this picture. I have a small rubber grommet that will fit in this notch nicely but I will wait for the final installation to insert that.

Categories: Fwd Fuselage

Installed Fuel Pump Connector – 1 hr

November 5, 2012 Leave a comment

Monday Nov 5, 2012

I only had about an hour tonight so I installed a Molex connector on the fuel pump wires (both sides of the connector are mated here) and mounted two zip tie bases on the F-782 to secure the wires. Those zip ties will also keep the connector secured in place.

 

Then I put the fuel pump section back in the cabin with the fuel transfer line to the firewall. Now the area in front of the pump is wide open for routing wires until I install the front section of the F-782.

Categories: Fwd Fuselage

Current Limiter Installed and Misc. Tasks – 5 hrs

November 4, 2012 Leave a comment

Sunday, Oct 4, 2012

On Saturday the weather was warm, humidity was low and I had a few parts in the “to paint” pile so I fired up the paint gun. I primed the cabin air vent brackets, the firewall doubler for the current limiter and shunt, and the custom bracket I made for routing air lines in the aft fuselage. I also painted the doubler and air vent parts with JetFlex to match the rest of the interior. The doubler is not shown in this picture.

Here is the primed and painted doubler installed on the inside of the firewall (the one on the right).

And here is the ANL current limiter and shunt installed on the engine side of the firewall.

I also did some work routing wires from the ADAHRS to the forward cabin. I bought a bag of zip tie bases from McMaster-Carr. The nice thing about these tie bases is I can mount each one with one pop rivet. I installed four on the aft side of the vertical rib next to the bellcrank and routed the wires straight down to about 10 inches above the bottom skin. I put one more on the side of the vertical rib so I could route the wires away from the bellcrank. I also wrapped the wires with a piece of spiral wrap to protect it from scuffing. Pay not attention to that rats nest of air lines.

So next I cleaned up the air line routing using the custom bracket I made to guide the lines away from the bellcrank. This looks much better now. I will use pop rivets to secure that bracket once I feel confident I am done climbing back in there.

The air lines route through a piece of plastic conduit to right below the pilot’s seat. From there I drilled four holes and installed snap bushings to route the blue (AOA) and green (pitot) lines out this side of the fuselage to the left wing. The green line has a T in teh outboard bay so I can route a branch forward to the backup instrument which will probably be a TruTrak Gemini PFD. That white tube you see in this picture is just a placeholder piece of scrap I had on hand. It will be replaced later by a green piece to the wing air connector.

The F-782 tunnel cover is an awkward part with a fuel injection boost pump installed. I’ve never liked the fact that you have to pull out the fuel pump and fuel line out to get access to the wiring in the front section. So I decided to cut the F-782 in half. The new aft section holds the fuel pump. Now I can install the pump and fuel line permanently and still have access in the front for wiring runs. It will also be better for maintenance and inspection purposes in the future. In this photo you can see the new cut line just to the right of the fuel pump. I will install two more nut plates so there will be four for each section to mount these to the floor ribs.