Mark

Most lower cargo compartments will have a heating system.

On the 767, hot engine bleed air is fed into a long tube running the length of the cargo compartment floor. The tube has holes to disperse the heated air.

A temperature switch controls a valve that either applies or stops the hot air flow.

The airline I work for has two aircraft that will allow cold pack air to go to the forward lower compartment. This is to keep the bay cold(er) while on the ground in hot airport environments. 
  
     
 

I might be wrong, but it looks like the wire list just adds a 0 in front of the 3 number wire designator.

When we look at a wire on the aircraft, it will only have the 3 number prefix stamped on he casing.

Again, I wish I could help with your question.

The charts you sent show wire bundle runs but, they do not show actual location on the aircraft.

If a detail of the runs is needed, the only way I could see it being done is when an aircraft is in heavy check will the wall and ceilings removed.

I'm sure Boeing has engineering charts that show the manufacturing locations of each run. I have never seen anything like this in their line maintenance manuals.

I have never found a reference as to exact locations of wire runs in the aircraft.

We've always hand traced wires with the use of a Fox/Hound device.

I had to delete your post with the whole chapter 91 PDF. I cannot post complete images of technical references on the site.

You hope the thing is there.
On this latest aircraft, our sheet-metal guy was able to replace the forward one without removing the whole detector/sensor/fan mount assembly.
A one hour change could of changed to a whole day affair. 

ELT's output two frequencies. 121.500MHz and 406.025MHz.

The 121.50 signal is just a tone. Rescue operators use a device to look at signal strength and direction to find the location of the ELT transmitter.

406.025MHz is a digital burst of data that reports encoded aircraft/owner information, a unique identifier number, and Latitude/Longitude position information.
A good explanation can be found here .

We usually try not to send data or tone out in to the open air during testing. Either a direct co-ax cable can be connected between the ELT antenna output or a shield can be placed around the antenna with a co-ax leading to the tester. Direct hookup is the preferred method.

This is not to say we can't just send signals out without shielding. The allotted time frame for testing in the USA is during the first five minutes after the top of the hour. We usually call the tower to inform them that a test will be conducted.
  
 

Those are internal relays.

Two lines, normally open.

Two line with diagonal, normally closed.

Abbreviations such as GCR, Generator Control Relay.

UV, Under Voltage.

OV, Over Voltage.

These are depictions to simplify the circuit. There doesn't have to be a physical relay. It could be an actual transistor that's doing the job. They could be logic circuits also.

 

Further explanation.....

The square opening at back of the operating blower is used for discharged air.

When a blower is running, its own flapper is being pushed back to let the air escape.

The non-running blower will have its flap pulled "in" because of the suction through the manifold.

We recently had a aircraft with a #1 blower failure (the #1 is the primary and is powered up first).
The blower failed which caused the system to use the #2.
The flapper on the back of the #1 was missing.
As the #2 was blowing, air entered the back of the #1 blower into the manifold.
No air was drawn through the detectors and the pressure switch was not being activated.
The system threw a EICAS message of "Cargo Det Air" because all smoke detection in that bay was inoperative.
  
Crappy image, but  it shows the location of missing flap for the #1 blower.
  
     
  
Replacement flapper.
  
     

 

We don't troubleshoot component internal workings.

If a system is failed and a replacement unit corrects the problem..... we're done.

Internal repairs are done at the shop level. Tests and certifications are required before the unit is returned to service.