Aircraft Engine Icing

Moreland - Paper #2

Weather Issues

Wesley Moreland

Eastern New Mexico University

AVS 310

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Moreland - Paper #2

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Conventional wisdom and standard aviation theory teaches pilots that there are two basic

requirements for ice formation during aircraft operations; freezing temperatures and moist air.

Standard precautions and training regimes do an adequate job of preparing pilots to anticipate,

recognize and take appropriate actions to avoid, prepare or clean their aircraft of ice formation.

However, since 1988 there have been 150 documented instances of a phenomenon known as

engine core ice accretion. This phenomenon has set the aviation community on its ear as the

recorded instances have not been during flight in traditional icing conditions; but, rather in

relatively clean air, during summer operations and above tropical regions. To complicate matters

more, the accumulation of ice is not traditional external accretion on the engine nacelle or inlet

structures; but, internal accretions found in the core engine compressor that is thought to be fairly

immune from ice formation as a result of the elevated operation temperatures. The one common

thread, drawn from the 150 instances, is high altitude flight in or around major thunderstorms

with large concentrations of ice crystals being emanated from the top of these storms.

The thought of an airplane flying in the summer over the tropics and having the engine

choked with ice and flame out is difficult to comprehend. Tom Ratvasky from NASA’s Glenn

Research Center in Cleveland, OH is quoted; “it’s not in one particular type of engine and it’s

not happening on one particular type of airframe. The problem can be found on aircraft a big as

large commercial airliners, all the way down to business-sized jet aircraft.” Although no accident

has been caused by engine core ice accretion in the past 23 years, there have been some close

calls. Most notable is a 2005 event when both engines of a...