767-200 dead APU Battery

[zerozero]

Hoping my question doesn't reveal any remedial systems knowledge, but I'm curious after recently reporting to a/c with dead APU battery.

Why isn't the system designed to be able to start the APU on ground power?

I have a hunch, but I'd like to hear your ideas.

We accomplished engine start with external air and departed with APU deferred.

Thanks.

[LeadSled]

0/0
Get into your manuals, and look at what feed directly of (hot bus) the main and APU battery, therein lies the answer.

[zerozero]

Right, fire detection and protection.
That was my hunch. Just needed a little confirmation. Thanks.