N254MR

I've decided to install and leave fuses in the circuits that have both power switches and wiring that is completed all the way to the device -- no bare wire ends -- such as alternator switching, E-BUS ALT FEED, EFIS 2 ALT FEED, etc. Those rest of the circuits, those having either unterminated wiring or no switch will have to wait for their respective gear or other loads, for obvious reasons. Getting the fuses in to stay, where I can, will reduce some of the thinking/remembering that will be required to have power where it's needed down the road, and not have it where it may still be unsafe. It will also cut down on wear and tear of the fuse socketes. When I get the last of the testing done on this panel, I'll lace up more bundles behind that I've left open for possible changes, and get this thing mounted where it's supposed to be -- clock and all. Yea!

Several hours of testing the left panel functions have produced good results. One switch was mis-wired (easily fixed) and there is a short somewhere in the wire between the A/P switch and the A/P harness D-sub connector. I'll open the D-sub hood to track it down, which shouldn't be too hard. I haven't yet tested the low voltage and overvoltage protection circuitry, but on all other circuits, DC power is showing up when and where it's supposed to show up, including the oil pressure switch, fuel tank gauges, elevator trim actuator, etc. The lighting circuits, dimmers, and LED indicators work, including the LED indicator wires going to the center panel. Load stress testing will be done after avionics and other gear are installed.

There were a couple of false starts when something didn't seem to work as designed at first -- resulting in considerable head scratching -- before I realized I needed not one, but two or even three fuses in place to allow that function to work as it should. I burned several fuses, but only because it's not easy for my clumsy fingers to place the VOM probes in some of the tight spots -- like the back of the radio stack -- without shorting out to nearby metal.  No problem, that's why I was using small fuses! It was great to be able to print out the Fuse Assignments page of the electrical spreadsheet, as it was an excellent guide and logging tool for these tasks.

There were surprises, mostly of the good kind. The first circuit I tested on the MAIN BUS was the START button -- just because it's at the top of a column of fuses. The starter contactor clunked ON just fine, but I was so focused on the voltmeter connected to the output that I was momentarily very surprised to see the associated red LED flashing away -- just like it's supposed to! What a fine sight. (That LED indicates the starter contactor is activated. If it continues to flash after the START button is released, it would indicate a stuck or otherwise faulty contactor, or toggle switch.) This momentary astonishment upon seeing an LED suddenly fire up when it was supposed to happened several times. Great fun! 

The bottom line is that after planning this over a period of years, followed by many months of building, not to mention tweaking and re-building, it is incredibly satisfying to find almost everything working just as it should on the first go.

Moments ago, I finished connecting up the left side panel. Whew! Including both sides of the panel disconnects, there are 126 point -to-point connections. The only unconnected quick tab there in the lower left is the low voltage test port. The three white wires on the right are indicator feeds to the LED annunciators on the center panel. Fortunately, there is very little actual wiring needed to connect the center and right panels, as most connections are via harnesses and plugs that are already done.

All that wire makes moving the panel quite stiff. After bundling the wires a bit more after testing, it will be a chore to slowly get the panel into place, when that time comes. For now, it's time for comprehensive and careful testing, recording the results. Obviously, it's not yet possible to check functionality of all the outlying gear, but I can check virtually all power & switching circuits to their current logical end, along with all the relays and most panel-mounted indicator LEDs. I plan to disconnect the new battery from the battery bus, tape up some loose wire ends in the fuselage and wing struts that may be energized, then run tests using an outboard, variable voltage power supply, with a small 1A fuse placed in each circuit, one at a time. After nearly six months working on the panel wiring, a moment of truth has arrived.

A recent visitor wondered if the all the quick tabs are adequate connectors for this purpose. "Won't they slide off?" The answer is that they are used extensively in commercial, certificated aircraft, because it takes some very high G's, in the twenties as I recall, to dislodge them. With fingers, they take quite a bit of force to dislodge. In my opinion, they are more reliable than ring terminals on screws, which can and do loosen with vibration.

A female Faston quick tab is available off terminal #3, which is connected to the onboard switch of the Perihelion Design low voltage warning system, of which the AUX/BAT switching is a bonus feature. The female quick tab test point can be used to test the low voltage warning system, as described in its documentation. It will be reachable from under the panel. The tab is amply covered with heat shrink to help preclude any short, but the tip is open enough for a male tab. Here you can also see the red (positive) lead from the AUX BAT LED which is jumpered across to the BAT BUS terminal of the E-BUS ALT FEED switch. The inline Quick Tab connection for that is also well covered with heat shrink for additional short protection.

Connecting wires to the bottom row of left side panel. The ring terminal wires are hardest to arrange, because the wires leave the switch at right angles to the terminal. It's necessary to lay the panel down flat to get at things adequately.

An updated electrical spreadsheet has been posted. New items, reflecting recent work, include quite a bit more on panel interconnects, updated details about flap controller & switch(s) installs, and various kinds of miscellaneous notes -- most about wire terminations, why and where they are.

At last, the left panel terminations are done, ready for the panel to be attached. Days of work to get here. This may look disorganized, but it ain't. There's actually a bundle for each switch or other connection. Everything has disconnects, whether Quick Tabs, DB-sub or Molex connectors. The prominent black connector at top center is for the EI SC-5 clock. The silver DB-9 connector just above that is the consolidated ground connections for all the low current left panel grounds -- LED's, etc. The white plastic Molex connector below those carries the starter wires. There's another DB-9 just above the big piece of blue tape in the middle, which is for the (6) A/P source select wires, alternator sense and stuck starter wires. The bunch of half a dozen wires hanging down below the panel are connections for annunciator LED's on center panel section. At the very bottom, the A/P roll servo cable is coiled & taped to the side wall.

At long last, the FPS-Plus Reflex flap controller is all wired up. The picture below is a little disorienting. The view is looking up under the panel and to airplane right. The firewall is on the left, and the controller is mounted upside down under the right side relay shelf. Following a suggestion made by Bob Nuckolls somewhere, each wire that goes into this blue "European style" terminal strip has been tinned with solder first to make a solid wire that's more crush proof than individual copper strands, which would get pretty mangled under compression by the set screws. The solder tinned end is then lightly coated with the ubiquitous TefGel for a little additional anti-corrosion protection. All that plus lableing takes a lot of time because, although I've been able to do most of the other panel work from the front of the panel, through subpanel cutouts, all this work has to be done upside down in pretzel position.

I'm thinking of mounting a thin sheet of acrylic to cover the controller wiring. In heavy turbulence, or even flailing about while reaching back into the baggage area, the co-pilot's shoes could get thrown up there... which is one of several reasons all the other wiring is so well protected in this area.

While working on final switch hookups for the left side panel over the last couple of days, it's been essential, not mention convenient to record the details of the final switch hookups, focusing on the wiring and operation of things, while checking and re-checking. Perhaps the most complex switching accompanies the mult-modal, multi-layered electric flaperon system. Some new documentation has been added to the Design and POH sections of the Library to explain the wiring and operation of the system. These are works in progress, and will be improved from time to time. Although the notes added today are text, I'll be adding more and more to the documentation sections of the web site, including schematics of various kinds, as details are finalized "on the ground."