FADEC
(Full Authority Digital Engine Control)
2/6/05
I had ordered the FADEC cabin harness kit a while back from Aerosance with annunciator box for two LED's rather than two incandescent lamps. Unfortunately, I thought the lamps were part of the ACU, but that is not the case. Which is good in some respects, but bad in others. Good because I have enough lamps in my warning lamp strip to accomadate the FADEC Caution, FADEC Warning, and the Fuel Pump lamps called out by the FADEC wiring diagram. Bad because the lamps I have are incandescent! Doh! I need to call Aerosance and see if I can exchange the unit.
The FADEC cabin harness kit arrived just before the christmas holidays, but I haven't had much chance to do anything with it until now. The cabin harness is pretty chunky! Shielded cable everywhere!
My first task was to figure out the best place to put the bulkhead connectors through the firewall. I made a doubler plate out of 0.063" sheet, and proceeded to make the round holes with an anti-rotation flat on them. Now that was fun! Lots of filing.
Here are the connectors in place. This is the cabin side.
This is the firewall side. The two ECU's will be mounted below on the lower firewall. It's gonna be a squeeze, because my oil cooler is going somewhere there too!
2/14/05 Update
I had ordered the the wrong box and after talking with Aerosance, they said, "Sure, no problem, just send it in, we'll get the right one out to you!" Sweet!
I also needed to talk to a tech about using toggle switches instead of a conventional ignition switch. They said that when Enable A and B are grounded, the system ignition is off. Easy. All I need to add are a couple of SPST switches. I also need to change out my fuel pump switch for a SPDT switch as you can have the pump in the ON position or the AUTO position. In AUTO, the FADEC controls the pump.
3/6/05
I had a play with the FADEC stuff too today. I got the new HSA box for incandescent lamps. I wanted to get all the wires routed and connected where I could, but I ran into a snag. The power and ground leads for each item are a two conductor shielded cable. This means that the grounds need to be near the power busses. Well, in my plane, that ain't so. There's a lot of wire in the cabin harness. Too much. Trouble is, you can't really trim any of it because of the plugs used. Some of the leads I can probably shorten, it doesn't seem like the shield is grounded anywhere in the harness. Time for me to make a call to Aerosance. Hopefully, they won't get fed up with me! I also have a fuel pump lamp cable. I couldn't find a reference to this on the wiring diagram. Hmmm.
I got another DPST Switch for FADEC B. I could use a SPDT, but the DPST switches are all the same type that I have in the main switch panel, so they all match. I'll just use one side of the switches for each FADEC CPU.
3/20/05
I got a 2-10 type On-On-On switch from B & C yesterday, so I mounted that on the switch channel. This will be for the fuel pump. The switch will be wired for Off, Fuel Pump Auto, and Fuel Pump On. In the auto position, the FADEC will controll the fuel boost pump. When the cabin harness came, it came with a relay. It has the strangest connections on it I've ever seen! If anybody has any idea of how I'm supposed to hook up (pun intended) wires to this sucker, drop me a line! Right now, I'm assuming I twist a loop in the wire and solder the sucker on there. This will be mounted in my centre console, so I came to a bit of a standstill with the wiring for this today since there ain't no centre console in existence yet.
5/1/05
I did a bit more wiring today for the FADEC. I spoke to the guys at Aerosance about cutting some of the wires shorter, and they had no problem with it. I also have a Power Sense B lead, which I don't need for my HSA. They said I could cut it off. I trimmed it as short as I could and shrink wrapped the end. I wired in all the warning lamps today. These are FADEC Caution, FADEC Warning and Fuel Pump.
Here is the connector that goes to the warning lamp bar.
I also partly wired the Enable A and B switches. These replace a standard ignition switch. Enable A & B are grounded to turn off the system, similar to Magnetoes. I guess they do this for easier retrofit into other aircraft. I still need to add the ground leads.
6/19/05 3 Hours
I didn't really spend too much time at the hangar today, due to going out to an Oasis concert last night. It was absolutely great. So, I needed a bit of a lie in this morning!
I finally got around to mounting the FADEC busses. I chose to put them in this location to try to minimise wiring runs. Hmmmm. Easier said than done with all this stuff going on behind the panel. Here you can see I have already wired the feeds.
I also got the switch wired. I ran the FADEC A from the main bus, and the FADEC B from the E-Bus. With the dual alternator system, I think we should be OK as far as redundancy goes. Dan Parson's spoke to the FADEC guys and found out the current draw for the system is around 5.5 amps. I probably could've got away with using thinner wire for these runs, but decided to go with 14 gauge. The run has to go from the main bus and E-Bus to the switch and then to the FADEC busses. I ran the ground wire for the Enable A and B while I was at it. You may notice that these switches are different to the ones I had a couple of shots back. I figured if I got some double pole on-off-on switches that I could use the same switch for the FADEC power and the Enable grounding. When the switch is down, the system is off and the Enable is grounded. When the switch is up, the system is on and the Enable ground is disconnected. I was considering not having switches for the system power at all, and just wiring the FADEC busses direct to the main busses, but figured it might be a good idea to be able to isolate a system properly. I guess it's on the Aerosance drawings for a reason. I might give Aerosance a call to make sure my switch arrangement is acceptable.
6/21/05 2.5 Hours
I stopped by the hangar tonight on the way home from work. A first for a long time. I had made some wire markers at home last night, so I could finish up the cabin wiring for the FADEC.
I spoke to the guys at Aerosance today to ask about my switch set up. Turns out, that's what they do on the STC for the Beech Bonanza, so looks like I'm on the right track! Magic!
Tonight I labeled the wires going to the switches and the FADEC busses. I also got all the ECU 1 wiring out of the way. Here's a pic showing what's going on.
The fuse block on the left is FADEC bus #1, and on the right is FADEC bus #2. So far, I have ECU 1 wired. This comprises four wires paired up with their respective grounds, PWR & GND A, PWR & GND B, SSA PWR & GND A, and SSA PWR & GND B. You can see the power wires going to the busses. All the PWR A's are heading to Bus #1, and all the PWR B wires are heading to Bus #2. This provides redundancy if a power supply path should fail. A similar thing is done with the grounds. My ground block has two strips connected to a plate. Each strip has two rows of connectors. It's the typical B&C ground block. All my GND A's go to one of the strips, and all my GND B's go to the other. That way, if one should come off by a freak of nature, then in theory, the other should keep the whole thing alive, including the pilot & passenger!
I still have ECU 2 to do, and the HSA (health status annunciator). These also have redundant PWR & GND's. By the time I'm done with this, there'll be a lot more wires connected to these busses! I ran out of 2 amp fuses too, so I need to go get some some time. I'll be stopping by tomorrow to wire ECU 2 and maybe I'll have time to get the HSA done too.
6/21/05 2 Hours. Yeah! I broke 1000 hours today!
This evening, the weather was really nice, so I broke out of work a bit earlier to wrap up the FADEC cabin wiring, which includes ECU 2 and the HSA. It all turned out pretty good, and I got rid of a lot of excess wire from Aerosance. I still have one long lead, for the Serial Interface but it has a special plug on the end of it, and I ain't about to break into that. I guess I'll just coil up what I don't use. It's not really that much.
Here's the rest of the wiring to the FADEC busses. You may have noticed that none of my fast-on terminals are pushed on fully. At this point in the game, I may need to pull 'em off to rearrange wire runs and stuff. All my wires are like this at the moment. When the time comes, I'll push all the terminals on properly. Looks like I'm close to running out of ground points! Fortunately, I'm almost done with electrical stuff. (Famous last words!)
Here's a tidier bundle of wires. Much better than they were before all hanging out of the plane! Sorry about the lame photo. I'll take a better one on Sunday.
One of the challenges I decided to take on today was the FADEC engine harness. I was having a spot of trouble trying to figure out how this thing was routed. It seemed to be a bit of a stretch between all the sensors. After much trial and error, I think I finally may have something!
I started by putting everything that had no leeway into position. One of those items was the fuel pressure sensor wires. There's absolutely no slack in these at all. The fuel sensors are so long. I hope it will clear the cowling. I might have to clock the fuel distribution block around so the senders miss.
The other difficult ones were the manifold pressure sensors. Not enough cable here, and the intake runners are a bit of a squeeze.
After sorting this, I ended up with this mess at the back of the engine. It's no good, as the manifold pressure wires are too tight against the sump in multiple places, and the wires up to the top of the engine aren't going to work with baffles.
This won't do.
Or this....
So, I tried to move stuff around a bit. My main aim here is to give the wires some slack. Here's a shot of the rear on the engine with a routing that seems like it'll work. I'll take some more pics of the other areas as I tidy it all up some.
I messed about with trying to find a place for the hefty FADEC ECU's. They're humungous! Here's a likely place.
I think I need to hang the engine again... I put the info for this on the Firewall Forward page.
So, now we have our engine mounted, and some idea of where the cable runs are, we might be able to figure out the ECU locations a little more precisely. Remember when you do this, you need to allow room to remove the High Tension leads. It looks like my oil cooler will be going on the baffles. There's not much room left back here. Hmmm... These things will make great mass dampers for the firewall! I'm going to have to put some structure on the firewall to support all this.
