Possibly true? Years ago I set up an AOC (in Scotland) with a Cessna 310 which was not 'approved' for known OR FORECAST icing. Since met in Scotland 'forecast' icing EVERY day of the year this was a bit of a problem.
I eventually got the 'forecast' bit dropped. The a/c was fully 'de-iced' but had NEVER been 'trialled' by Cessna in those conditions and therefore was not 'approved'. In 1985 the CAA wanted tens of thousands of ££ to flight test it to clear the restriction.
Needless to say I always avoided 'known' icing
