The package firmware-b43-installer which was in the MintPPC repository did not work anymore for a while. Users of MintPPC could therefore not use the airport card. I deleted the packages from the server. To have a working airport, you need to make sure you have the following line in /etc/apt/sources.list:deb http://deb.debian.org/debian-ports unreleased main
You then need to install firmware-b43-installer from the mentioned repo:
sudo apt install firmware-b43-installer