Originally Posted by
Lord Farringdon
That's why we come here Megan. To learn something new. Thanks. Interesting phenomenon. I had to look that up and found a data sheet called Engine Power Loss in Ice Crystal Conditions. It's 2008 and mostly related to Boeing large jet transport aircraft so I'm guessing I'm alone in not knowing about this!!! in 2008 it seems they were asking for pilots to report events so that they could better understand the process that was going on. I imagine by now it is pretty well known and documented. As far as I understand from that albeit dated document I read, engine damage might occur but no hull losses had been attributed to the condition since the engine/s could all be manually restarted or kept going with auto ignition.
Disclaimer - I don't know anything more about what happened to the E-11A than what I've read here...
Ice Crystal Icing (ICI) I do know something about. For reasons that are not well understood, it's a relatively recent phenomena at least with respect to causing engine problems - first raising it's ugly head as an turbine engine problem in the early 1990s. While it's better understood now that it was 10 years ago, I'd wouldn't say it's 'pretty well known' or well documented. ICI is fundamentally different than conventional aircraft icing - supercooled water droplets that hit and freeze on unheated aircraft surfaces- ICI occurs at much lower ambient temperatures (too cold for supercooled droplets to exist) and is just what it sounds like - very small ice crystals that normally just bounce off of unheated surfaces (flight deck reports often compare it to the sound of rain). Heated surfaces - such as internal to an turbine engine compressor - are a different matter. In high concentrations, the crystals can hit a warm surface and melt, but more crystals impacted the liquid water causing it to re-freeze. As a result, ICI forms at surface temperatures where it's far too warm for conventional icing (sometimes as high as 30 deg. C). Large amounts of ice can form in warm parts of the compressor, then suddenly shed and quench the combustor flame - sometimes damaging compressor blades in the process. Some engines are far more susceptible to ICI (again for reasons that are not clearly understood) - the CF6-80C2/80E was particularly bad, as was the GEnx (in both cases it has been successfully addressed with FADEC software, although in the case of the CF6-80C2 it took multiple tries before they got it right). Compressor damage bad enough to prevent continued engine operation is rare, but it has happened...
I remember that there were a few biz jet engines that had big problems, but I don't recall which ones - sorry...
While ICI can happen anywhere, it's most common in the Pacific rim area. Enough so that the PW2000 went for a couple decades without ever having an ICI problem, until Delta started basing a few 757s in Japan, after which they had a few apparent ICI related flameouts
.