In early 1990s a BAe146 suffered a total (yep all 4) engine failure/s due icing. The aircraft was operating at FL310 between Karratha and Perth when the crew called mayday.
Engine restart was achieved when the aircraft was around 10,000ft. VH-JJP was the reg operating as Airlines of WA flight. Since then all Australian 146s have been limited to below FL290.
I am pretty sure the limitation is still in effect. ATSB report should be available on the ATSB site.