Icing

[WebMaster]

Originally posted by kevin
It has long been said that one should wait until you have a good load of ice (1/2 to 3/4 of an inch) before excercising the boots. Recently, one of the AOPA authors, I think it was Horne, did some research to see where that rule came from, and although oft repeated, Horne could not find the source of the rule, and could find no evidence that more frequent actuation of the boots removes less ice, or really causes the boots to form a pocket inside the ice on the leading edge, as is said.

Kevin

It actually comes from Ernest K. Gann, talking about getting ice on the wing of a DC-3, ages ago, when DC-3's where the staple of the airline industry. He reported in one of his books that they fired up the new fangled boots, it was too soon, and the ice formed a bridge. He was in trouble. Interestingly, later day attempts to duplicate that have never worked.

Originally posted by kevin
Sometimes, the boots don't work.
Kevin [/b]

Which is why you should try to inflate them, on the ground, before taking off, and verifying that they work... Obviously, you can't check the boots on the horizontal stabilizer.

I do recall Bob Cook writing that he lost the front vacuum pump, while cycling his boots, going into IAG during the winter. Obviously, he needed them, and not only lost the ability to cycle the boots, but also lost a source of vacuum.