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Wiring access and where to put electrical components

bomber_JB

Active Member
On a quick build 10 we?re at the end of the fuselage construction where we are to attach the upper forward fuselage section. The empennage and all control surfaces are attached. There is a 8-10 week wait for the finish kit (gear and engine mount included) and I want to keep moving forward with wiring. I?m OK with attaching the wings temporarily with pins to accomplish wiring. I?ve built an RV-7A and am really concerned that if I attach the upper forward section that I?m severely limiting my access for electrical wiring and signal wiring for the panel. The panel is all Garmin and I can pre-wire on a bench. But running electrical wires with the foreskin on is really difficult.

Question 1: Do I remove the foreskin on the upper forward fuselage section to facilitate wiring? We?ve paid to have riveted as part of the QB.

Question 2: The RV-7A had the battery on the forward surface of the firewall. The voltage regulator and main contactor were close by with the single point ground block on the aft side of the firewall The 10 has the battery aft of the baggage bulkhead with the contactor near. Where do you put two voltage regulators, a Lightspeed electronic ignition and a single point ground block? If they all go forward then I?m back to the issue of having the foreskin off for access to wiring. HELP!
 
Forward skin

My opinion only:

Having the top forward fuselage off can help if you know EXACTLY where everything is going to go. The biggest benefit would be to be able to cut the clearance holes in the sub panel while it is on the bench. Unfortunately, a standard length radio will NOT fit between the instrument panel and the sub panel.

The problem is knowing WHERE to put the holes.

Another issue is mounting items BEHIND the sub panel (between the sub panel and firewall). It is easy to do when the panel is on the bench BUT those items will be VERY difficult to get at once the forward fuselage is riveted on...I did not mount anything on the backside of the sub panel.

If you are going with an EFIS system, there will be one or more large holes in the instrument panel that will allow easy access to the face of the sub panel.

I mounted my two B&C regulators and the single point ground on the sub panel. I actually made racks where a traditional radio stack would go, even though I am only going to have a GTN 650 go though the sub panel. I am mounting the various units on those racks as well as the sub panel.

To get back to one of your questions, I did all of this with the top forward fuselage riveted in place. Once you remove the instrument panel blank, there is quite a bit of room to work...
 
I did a slow build fueselage and the last thing installed was the cabin top and the forward skin. I modified the forward bulkheads a bunch to accommodate mounting electrical parts and then riveted the assembly to the fuselage. I also did all the wiring before it went on it’s legs. Everything was at a very reasonable working level and absolutely perfect access. I did all the work standing outside the fuselage.

You don’t need the wings on to wire if you use connectors. Testing is delayed until the wings are on, but just put in big service loops.

I would strongly suggest either removing the skin or just buying all new parts. I used kitlog pro with a daily update.

http://www.mykitlog.com/users/index.php?user=diablouser&project=2128
 
and...

Remember that it is FAR, FAR easier to rivet that forward section on BEFORE the engine mount goes on. After the mount is on, it is doable but challenging...
 
A lot of the sequencing depends on when you are going to purchase the engine and your avionics.

You can mount the upper forward fuselage after the canopy is installed, and with a little more difficult, after the engine in mounted.

IMHO the best sequencing would be to complete everything inside the fuselage before it is on gear. Install the avionics into the upper forward fuselage on the bench and install the entire assembly onto the plan and make the remaining electrical connections. Then the windshield. After that is done then put it on gear. Main gear fairings are easiest with out the engine and wings attached, but no big deal doing them any time. That leaves engine FWF and wing attach.

More on point to your original inquiry, there is no advantage to removing the top skin from the UFF, just leave the entire assembly off.
 
Oh, I disagree...

It is NOT a little more difficult to rivet the UFF with the engine on, it is SUBTANTIALLY more difficult...
 
I ran all the wires I could think of plus some spares from the panel location to the various points rearward before installing the fiberglass cabin top. It made running the conduit and wires much easier. I also determined the locations for my antennas and installed the doublers and holes for them, and then ran the coax cables to them and installed the BNC connectors, all before installing the cabin top. I did not remove the forward top skin from my QB fuselage for any of this work.

I also installed the landing gears and fairings before hanging the engine, as it was much easier/lighter to lift the fuse onto the workbench without the added engine weight. But I did install the fiberglass cabin top, the doors, and all the windows and windscreen before mounting the landing gear as that was easier when the fuselage was sitting on the low cradle which allowed much easier access.

I'm sure there are several different building sequences you can choose from. I just found the sequence above most convenient for me.


Regards,
 
One more data point..

..I permanently riveted on my forward fuse top after talking with another 10 builder who said he did everything with the front panel removed. After installing it, it's true. There is lots of room to access the subpanel right through the front. The other added benefit, is that all the layout can be done knowing exactly what things might be in the way.
 
Another issue is mounting items BEHIND the sub panel (between the sub panel and firewall). It is easy to do when the panel is on the bench BUT those items will be VERY difficult to get at once the forward fuselage is riveted on...I did not mount anything on the backside of the sub panel.

If you are going with an EFIS system, there will be one or more large holes in the instrument panel that will allow easy access to the face of the sub panel.

I mounted my two B&C regulators and the single point ground on the sub panel. I actually made racks where a traditional radio stack would go, even though I am only going to have a GTN 650 go though the sub panel. I am mounting the various units on those racks as well as the sub panel.
My QB build was a 1000 flying hours ago so I don't recall the details. But I would reinforce everything said above.

The area between the subpanel and firewall is extremely inaccessible once flyiing. I mounted two B&C regulators to the back of the firewall - recently needed to tune the bus voltage and had to build a special tool to get to the screw. Don't put anything on the back of the subpanel and use blind nuts for everything mounted anywhere.

I have ground block on the firewall with tabs on both sides - works well but the subpanel mount sounds better. Not sure how/where to run groundstraps to the engine mount.

I'm just completely a small panel upgrade that include replacing (1) old, small screen GRT with a large screen HXr. The access to behind the panel through the opening for the HXr is stunning! Big screen EFISs really ease access.
 
My QB build was a 1000 flying hours ago so I don't recall the details. But I would reinforce everything said above.

The area between the subpanel and firewall is extremely inaccessible once flyiing. I mounted two B&C regulators to the back of the firewall - recently needed to tune the bus voltage and had to build a special tool to get to the screw. Don't put anything on the back of the subpanel and use blind nuts for everything mounted anywhere.

I have ground block on the firewall with tabs on both sides - works well but the subpanel mount sounds better. Not sure how/where to run groundstraps to the engine mount.

I'm just completely a small panel upgrade that include replacing (1) old, small screen GRT with a large screen HXr. The access to behind the panel through the opening for the HXr is stunning! Big screen EFISs really ease access.

I put my grounding bus on the sub-panel, as I figured it would be misery if it was on the firewall. I will let the aircraft structure be the ground to the engine and am not worried that it don't have a wire to the engine. The two ground straps provided by Van's connect the engine to the mount and the mount has a good electrical connection to the aircraft structure. This grounding approach is used in the kit instructions and I am sure we would have heard about any issues with it by now if they existed. Most sensors on the engine side have a dedicated ground wire anyways, going back to the EMS. If using Kavlico's, only the oil temp sesnor is grounded to the engine and the more modern RTD based sensors have dedicated grounds.

Larry
 
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