B757 and Freezing Rain

[captjns]

Originally Posted by hoey5o

So can anyone comment on whether the B757 (uk based) is allowed to operate in freezing rain as getting an authoritive yeh or neh seems a little difficult at the moment. I believe the UK CAA dont approve any commercial aircraft for severe icing but I may be wrong. Perhaps Boeing/FAA approve ? The manuals dont seem to mention it.

Like all transport category transport aircraft, the B757 was certified by the FAA to fly through known icing. The WTAI system is able to cope with server icing conditions for a limited period of time however. I have not come across any limitations regarding operating in severe icing conditions. The engines whether P&W or RR are subject to vibration when the fan blades accumulate icing do to the fan blade balance. Here is an excerpt from the Boeing 757 AFM which refers to Engine Anti Icing. I have the AFM on my computer. However unfortunately, I can’t copy it since it is copy write protected.

Anyway here it is word for word:

“NOTE: Under all but very server icing conditions, ice will shed when thrust is reduced to idle, eliminating the need for the need to subsequently apply higher than desired thrust.”

Perhaps specific operators insert provisions regarding prohibited operations in severe icing all together. Regardless of what the manual says, if possible, the safest operating procedure is to avoid moderate to server icing conditions.

I hope this was of some help to you.