I vaguely recall most FAA certificated airplanes to be able to handle light/moderate icing only.
Lots of dust in my CAR 4b and FAR 25 pages...
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However would mention that the L-188 Electra could handle "heavy icing".
At least is what I recall vaguely from a classroom discussion 35+ years ago.
Maybe our illustrious
411A can clarify the certification of the superior Lockheed product.
Happy contrails