Mark

 Assembly and Part Number
  
     
     

  
  
 

On the repair, we thought that we could just replace the wire in question. That was the wrong assumption.
You replace the the entire harness assembly from mid-strut down to the user systems (brake temp, wheel speed, and one gear tilt sensor).
  
     
  
Before tackling the job, I made up a by-pass jumper and connected directly from the #3 speed transducer to the J-Plug at the mid-strut level. Our voltage readings were correct.
  
     
  
Now..... the "fun" part of replacement.
  
     
     
     
  
Baked on carbon dust, Skydrol carbon dust, oil carbon dust..... you're covered, your tools are covered, clothes..... "not" the most pleasant job!!!
  
 

Troubleshooting a Anti-Skid issue which was faulting the #3 wheel.
  
  
We looked at the output of a functioning transducer vs. the faulted one. The drill being used only had two speeds (fast/slow), but it was able to show what our issue was.
  
     
     


A/C voltage should increase with speed. On the #7 wheel input, it did. On the #3, it "dropped" as we spun it faster.

Our problem? A high resistance short between both wires and shield of the twisted pair wire coming off the back of the transducer in the strut.
  
     
     
 

Pretty sweet! You're getting that 3D printing skill-set "rollin-on".

And, then again.... It doesn't matter what system is installed, this won't work very well!!
  
     
 

I've asked around (even the heavy check guys), no one seems to know what that means. Is there any type of preamble to those work cards? A lot of acronyms are explained there.

Can you please send image.

An "APU Door" EICAS message is a indication that the APU air inlet door is not in the commanded position.

It shows when the door is open (or not fully closed) when commanded closed or closed (or not fully open) when commanded open.

The indication system uses the same two relays (K176 and K547) that are used to drive the door open/closed. Ref:  rotate.aero/forum/767-49/399-apu-inlet-door-position

If the EICAS computers see a ground on pin "E1" of plug "F", they will show the "APU Door" fault on the crew display.

In the schematic below, the APU is shown shutdown. In this condition both relays are relaxed. If the internal switches "1 and 4" or "8 and 9"  are in their correct positions, no ground will be present at the EICAS computers.
  
     
  
We recently had the "APU Door" warning on a aircraft that had the APU off with the inlet door closed. It turned out to be the internal switch contacts on 8 and 9. They were remaining connected with the actuator fully retracted (or closed) position.

After removal, I used a 28VDC power supply and a meter to verify our results. I applied power to pins 6 and 7 (actuator retract). Before power was applied, I had continuity on pins 8 and 9. After full retraction..... I still had continuity on those same pins.
  
     
     
  
The easiest way to verify bad actuator switches with the warning on and the door visually verified fully open or closed..... is to just disconnect the actuator plug.

If the EICAS warning goes away..... the actuator is at fault. (And yes, there could be some other funky shit going on if one of the relays stuck on, the warning system had a broken or shorted wire..... but we'll just keep it as simple as we can for now!!)
  
 

Gasket P/N 3876244-1

The normal takeoff procedure is to manually take the engines to 70% at the beginning of the roll. At 70% the "N1" button is pushed which causes the TMC to takeover the rest of the throttle control.

We had a aircraft abort takeoff because "N1" didn't engage (I don't know why they just didn't take it, but I don't fly these things. I'm assuming safety is the issue).

We tried the test above when we could find no other issues with the aircraft. It worked, got signed off, and hasn't had a problem sense.