gee some of this is amazing.
61.355 Retention of personal logbooks
A person commits an offence if:
(a) the person is required to keep a personal logbook under regulation61.345 or 61.350; and
(b) the person does not retain the logbook for 7 years after the day the last entry is made in it.
Penalty: 50 penalty units.
so if your log book is stolen or gets burnt when the house goes up in a bushfire 50 penalty units.