Chapter 5 - Ground Crew Supplement

Inspection for Contaminants

113.  As part of the walk-around, the aircrew will be looking very closely at the aircraft. If it's snowing or raining, an icy wing looks just like a wet wing.

114.  You as ground crew must check your own area closely. The best testing tools are your eyes and your hands. If a surface looks suspect and conditions are ripe for freezing contamination, run your hand across the surface. If it is wet, you'll slosh water around. But if you feel thick water or a mild, gritty feeling, you are feeling snow and water or ice crystals and water. Light sheet ice is sometimes found over a coating of water. It will break or shift around when you feel it. Heavy ice, sticking to the aircraft, will feel pebbly, or feel too smooth. Heavy ice also looks slightly cloudy. Some ice is rough and hard to see through to the aircraft skin, while other ice is smooth and as clear as water. Snow accumulation is obvious: it looks like snow. But some areas of certain aircraft can fool you. For example, most jet engine intakes have a built-in heater to keep the intake clear of ice in flight and on the ground. If melted ice in the intake is allowed to refreeze (while overnight, for example) and snow falls on that refreezing water, you'll find what looks like some snow in the intake. Run your hand through it and you'll find a hard lump of ice with a fine cover of snow sitting in the intake.