Agaricus bisporus quote - followed up by ttcse
the problem was not the things freezing up, rather the thawed ice flowing back down the plumbing and causing varying and moving hydraulic blockages.
Try the following link and the authors 'third theory' re Qantas Airbus A330-303 in-flight upset (QF72).
The QANTAS Airbus A330 Inflight upsets