OG GarlicSalt

Probably not a PN change unless its part of a SB or AD, most probably a mod status change.

Both part numbers serve the same purposes and meet the same TCAS spec but the manufacturers and system are different the first pn is more of an all in one solution while the 2nd pn is part of the entire honeywell TCAS setup.

By no means an expert on this but I feel this should answer most of your question.

Somewhat, most wide body aircraft have some type of heating for the cargo to facilitate transporting animals or perishable goods.

Although it's not a temperature select like for the cabin.

Worked on these quite a few times never knew about the flapper, always suprised me how much smoke is actually required to set one of these things off.

Probably the pins listed are for installation into the rack and the plugs will come with their contacts.

Also if you see the fuses on the charger diagram, they are readily available for order easy to replace on the side and 9/10 times when a charger is failed that's the culprit.

Thanks Mark, that's the main reason I have been making these things. Mostly just to improve my skills in design but much more helpful with real life goal in mind.