I was on the road most of the week, which was a crying shame as the weather was pretty much perfect. I would have loved to go flying. Of course the good weather disappeared as soon as the weekend hit.

Yesterday I spent the afternoon at the hangar, attacking the standby alternator voltage regulator power wire. It turns out that I did not install the wire from the standby alternator control relay to the big capacitor by the voltage regulator when I was installing the aircraft wiring. It looks like I didn’t have a suitable ring terminal. I should have put this open item on my big open items list, so I wouldn’t forget it. But, I never did that, so this wire never got installed. Once I got flying, I found that the standby alternator wasn’t working. I finally dug into the snag a few weeks ago, crawling under the panel with a copy of the wiring diagram and a multimeter. I quickly discovered the problem, and ordered the needed ring terminal.

It sure would have been a lot easier to install this wire when I was doing the rest of the wiring. I had to run it all the way from the right side of the instrument panel to the left landing gear box area. I was ever so happy I had added the access door in the aft wall of the forward baggage area.

It cost me about 2.5 hours and a couple of skinned knuckles, but I got the errant wire installed and tested with a multimeter. I’ll test the standby alternator the next time I go flying.

I noted a long time ago that my 8 amp B&C Specialty Products SD-8 standby alternator wasn’t working. But, every time I wen to the hangar, I’ve either had more important snags to chase, or the weather was good and I went flying. This afternoon, the wind was howling straight across the runway, and I wasn’t too motivated at work, so I went to the hangar to finally attack this snag.

First, I compared the wiring diagram in the B&C installation drawings against my wiring diagram - they matched perfectly. Then I crawled under the instrument panel with a voltmeter to check my wiring. I found that there was no power at the voltage regulator. Tracing the wiring, I found that for some stupid reason I hadn’t fully finished installing all the wiring for the alternator control. I had not installed the wire that went between the control relay and the noise filter capacitor.

Now that I know what the problem is, I need to find the best way to run a 12 AWG wire from the control relay, behind the right side of the instrument panel, and the capacitor way over on the left side, on the front of the landing gear box. I’ll attack this fix in the near future, once I acquire anther 12 AWG ring terminal - the lack of one of these is perhaps why I never finished the job in the first place.

A few weeks ago I saw a posting on the Van's Air Force forum about the correct hardware to use to attach grounds to the airframe. The RV airframe is made from aluminum. The ring terminals on grounding straps are typically tin plated copper. When you put dissimilar metals in contact, there is the possibility of galvanic corrosion. If there is electrical current flowing, this increases the chance of corrosion. I had worried about the possibility of corrosion where the various components were grounded to the airframe, but I simply assumed that there was nothing that could be done to prevent it.

Another builder posted a question about possible corrosion at grounding points, and George McQueen, provided a very useful pointer to the material on this subject in FAA Advisory Circular AC 43-13-1B, Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair. I have a copy of this huge bible, a great reference for best practices, but I had missed the section on electrical grounds. AC 43.13-1B suggests to put an aluminum washer between the tinned copper ring terminal and the aluminum airframe. The washer and the airframe are made from the same material, so there won't be any galvanic corrosion at that interface. The corrosion, if any, will occur between the aluminum washer and the tinned copper ring terminal. But the washer is replaceable, so corrosion there is fixable.

I ordered some aluminum washers, and they arrived earlier this week. I corrected the ground connections to the airframe.

I was planning to use an alternator that I had purchased from Mark L, an RV-4 builder. Mark modifies automotive ND alternators to allow them to be used with an external regulator. But, I've reconsidered that plan, as I've seen too many reports from people who have experienced alternator failure. This is one of the most common failures. An alternator failure wouldn't be a safety issue, as I have an 8 amp standby alternator that will allow me to power the essential items indefinitely. But, I plan to do a lot of travelling with the aircraft, and an alternator failure while on the road would be a major hassle. It wouldn't be easy to purchase a drop-in replacement alternator, as a standard automotive alternator is designed to use its internal voltage regulation, and my wiring system is setup for an external voltage regulator. And I can't count on getting an identical unit from Mark L., as he basically modifies whatever ND alternators he can find.

B&C Specialty also sells modified automotive alternators. But they do things like install better quality bearings, and balance the rotating components. They have sold thousands of alternators, and the failure rate is supposedly pretty close to zero. And, if I ever do need a new one, I can get it shipped the same day. Their alternators are much more expensive than the one I already had, but I figure it is worth it to get better reliability, and a quicker replacement, if I ever need it.

MY 60 amp B&C Specialty alternator arrived last week. I'll work on installing it soon.

The battery tray was designed for a much larger battery than I will be using. I've got a standby alternator, so I only really need a battery that is big enough to start the engine. The stock design battery tray needed some modifications to be compatible with my smaller battery.

The basic tray has a U-shaped channel that sits on top of the battery, with bolts to hold it down. The flat side of the U goes down, with the two ends of the channel pointing upwards. My battery is quite a bit narrower, so the terminals would be close to the U-channel, and there was some risk that the terminals could short out against the channel if the battery moved a bit.

I decided to turn the channel over, so the flat side was on the top, and then trim the channel at an angle to make more clearance with the terminals. Putting the flat side up would have the channel only touching the battery on the edges, which would put a lot of pressure on a very small area. I trimmed some pieces of hard wood to fit inside the channel, to spread the load over a large area. The wood is non-conductive, so there is no risk of it shorting out the terminals.

At the bottom of the battery, you can see one of the pieces of angle I bolted to the battery tray to make it fit my much narrower battery. This is a small gap at the end of the battery that I need to fill with another piece of hard wood.

The bolts that came with the kit were a bit too short, due to the fact that I had turned the U-channels over to put the flat side on the top. I couldn't find longer bolts easily, so I used some threaded rod, and then applied some high strength LockTite to permanently attach some nuts to the top end.

The positive battery cable is about an inch away from the threaded rob, but there is some risk that it could move and chafe against the threads. I need to put a piece of rubber hose over the threaded rod to guard against that. One more thing for the snag list.

What a difference a day makes. Yesterday I was quite bummed out to discover that I would have interference between the main power feeder and the aileron pushrod. And I probably had interference in the same place on the right side, with a different wiring bundle. The main power feeder could be repositioned, as there was a loop at the battery contactor that could provide some slack. But the feeder has bundled with the remote compass wiring bundle, and any slack I could get there was going to require at least two trips way down into the aft fuselage to loosen and retighten the clamps.

Tonight I took a second look at things. Now I'm almost certain that the wiring bundle on the right side will be OK as is. And I realized that while the remote compass wiring was bundled with the main power feeder, it wasn't actually bundled with it in the area where the interference was. So, I wouldn't need to go all the way back in the fuselage to make any slack in that bundle.

I loosened up all the clamps holding the main power feeder, cut all the plastic ties that bundled it with the remote compass wiring, and loosened the power feeder at the battery contactor. Then I was able to gradually work it forward a bit to create some slack in the aileron pushrod area. I drilled a hole for another Adel clamp and secured it clear of where the pushrod will go. I still have to work the feeder straight again along its length, retighten all the clamps and put on new plastic ties, but I'm over the hump. I'm much happier now than I was 24 hours ago.

I've spend quite a few hours this week securing wiring bundles in the fuselage. I thought they were in reasonably good shape, but a close inspection revealed quite a number of areas where the wiring bundles could move around, or where there was risk of chafing on something. I've had to add quite a few extra clamps, and move some of the already installed clamps. I've found that a few wires had some slack in them, so I've had to chase that wire down the whole length of the bundle, pulling out the slack and moving it to the end of the bundle. Then I cut the wire and shorten it at whatever it connects to.

This evening I finished securing the main power feeder from the aft battery to the forward fuselage, and I thought I had finally finished all this wiring bundle work. Then I noted that both the main power feeder and another wiring bundle go very, very close to where the aileron pushrod will be. I can't tell exactly how high the aileron pushrod will be, so I can't say for sure whether I have a problem or not. I guess I'll let this one sit until I install the wings at the hangar. Hopefully it'll turn out OK. If not, I'll have to do a lot of repositioning of things to create some slack at the aileron pushrod area so I can secure things out of the way. That'll be a very big job.

I was in Wichita all last week, and didn't get back until Saturday night. I'm heading back on the road tomorrow too. :( I'm going to be on the road this summer quite a bit more than I had expected. But, I've got a whole bunch of vacation time saved up, and I'm going to take four or five weeks off whenever things slow down, so hopefully I'll be able to make some good progress then. I've got to get this thing flying.

My Odyssey PC-680 battery arrived while I was away. I bought it on e-Bay, from someone who seems to be making quite a business out of selling them. He has good prices, he sells a lot of batteries, and no one has registered a single complaint against him. The battery looks to be new, it was well packed, and it was fully charged. So, if you are looking for a good price on an Odyssey battery go to e-Bay, and look for batteries for sale from "odyssey_world".

I will have to make up some spacers to go between the edges of the battery tray and the battery, as it is a lot smaller than the tray. I figure I'll make something out of wood, varnish it and bolt it into place. I've also got to make up the battery cables, now that I can figure out how long they need to be.

I used some patch cables to hook the battery to the electrical system. I was finally able to do a functional test on the starter control wiring. The power supply I was using didn't have enough "oomph" to properly work the starter contactor.

I have learned a lot about aircraft electrical systems from Bob Nuckolls, his AeroElectric Connection book and the AeroElectric-List. One of the list subscribers put together a huge (310 page - 737 kB) Frequently Asked Questions based on the info posted on the List, and Bob Nuckolls has made it available on-line.

Date: Tue, 09 Mar 2004 14:20:39 -0600
To: aeroelectric-list@matronics.com
From: "Robert L. Nuckolls, III" 
Subject: AeroElectric-List: Frequently Asked Questions Compilation


--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"

List reader L. Holt has sent me a copy of his efforts to compile
a list of frequently asked questions from the Matronics archives
for the AeroElectric-List. This was a really BIG effort on his
part. I'm pleased that he has offered to share the product of
his efforts. I've posted the document at:

This is a BIG document . . . about 310 pages. You can use
the table of contents he crafted at the beginning to find where
paragraphs on a major topic have been gathered together -OR-
you can use the word search feature in Acrobat Reader to find
words and phrases in the total work.


            Bob . . .

            -----------------------------------------
            ( Experience and common sense cannot be )
            ( replaced with policy and procedures.  )
            (                  R. L. Nuckolls III   )
            -----------------------------------------

It's been a busy week, but unfortunately not enough of the busyness was spent in the garage.

I spent a lot of time running the strobe light and position light wiring, and working on the wire bundles under the baggage compartment and cockpit floors. I held off on creating the wire bundles until the vast majority of the wires were in place.

I had a depressing realization a few days ago - I had spent hours running the strobe light and position light wiring in the rear fuselage, and I just realized that I need to run the pitch trim wire in the same bundle. So I get to spend another few hours cutting the wire tires, running the pitch trim wire and making up the wire bundle again. And the bruises had almost disappeared from my arms where I beat the heck out of them against the bulkheads worming my way into the aft fuselage.

I'm getting ready to head to Wichita on Friday to do some King Air simulator training this weekend, and then a bunch of Global 5000 flight testing. So, I won't make a lot more progress before Christmas. :(