Zeppelins have the capacity of carrying 4 coal blocks as torpedoes or bombs, but since coal block bombs were removed, only torpedoes can be operated by this aircraft. By adding Bomb Bays to Zeppelins we can fix this.

I think they should carry at least 2 Bomb Bays like bombers or even more (like 3) since airships are supposed to lift more cargo than a bomber but this decision is up to Zaify.